Nastran bulk data writer (SOL 101/103) and deck.write steps (M3) (#24)

* Nastran bulk data writer: fixed-format entries, exact large-field reals, SOL 101/103 decks

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* Nastran writer tests: golden decks, a re-reader of our output, node order against Nastran's conventions

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* docs: Nastran writer in the roadmap, parity table and deck notes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* Nastran writer: simplify planning (subcases, one property table), stream cards into the deck, write through the VFS

ElementKind::corner_count/is_quadratic and Dofs::bits/from_bits join the model.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

* Nastran joins the shared deck formats; deck.write chooses steps for every format

nastran::write_resolved is the FORMATS row; Format::write_steps and with_steps write a subset of
steps (a Nastran run is static or frequency steps); problems go through the shared unsupported().

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

---------

Co-authored-by: jyviko <2501648+jyviko@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
authored and GitHub committed 2026-10-13 17:34:26 -04:00
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#![forbid(unsafe_code)]
pub mod abaqus;
pub mod nastran;
use std::collections::{BTreeMap, BTreeSet};
@@ -52,10 +53,40 @@ impl Format {
let text = (self.writer)(model, &resolved)?;
Ok(Deck { text, warnings: resolved.warnings })
}
/// Write only the named steps (in the model's order), or every step when `steps` is `None`;
/// for runs that hold some steps only, such as a Nastran run (static or frequency steps).
pub fn write_steps(&self, model: &Model, steps: Option<&[String]>) -> Result<Deck> {
match steps {
None => self.write(model),
Some(names) => self.write(&with_steps(model, names)?),
}
}
}
/// The model with only the named steps, in its own order. Definitions the dropped steps used
/// stay (the check warns about the ones no step uses).
pub fn with_steps(model: &Model, names: &[String]) -> Result<Model> {
if names.is_empty() {
return Err(Error::Model(modelcraft_model::Error::Invalid("choose at least one step to write".into())));
}
if let Some(n) = names.iter().find(|n| model.step(n).is_none()) {
let shown: String = n.chars().take(modelcraft_model::MAX_NAME_LEN).collect();
return Err(Error::Model(modelcraft_model::Error::NotFound(format!("step `{shown}`"))));
}
let mut out = model.clone();
let dropped: Vec<String> = model.steps().iter().map(|s| s.name.clone()).filter(|s| !names.contains(s)).collect();
for name in dropped {
out.remove_step(&name)?;
}
Ok(out)
}
/// Every deck format, one row per writer.
pub const FORMATS: &[Format] = &[Format { name: "abaqus", extension: "inp", writer: abaqus::write_resolved }];
pub const FORMATS: &[Format] = &[
Format { name: "abaqus", extension: "inp", writer: abaqus::write_resolved },
Format { name: "nastran", extension: "bdf", writer: nastran::write_resolved },
];
/// The format called `name`.
pub fn format(name: &str) -> Option<&'static Format> {
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//! Bulk data entries in fixed format, and the numbers in them.
//!
//! An entry is a name and a stream of data fields. In small-field format each line holds the name
//! (or, on a continuation line, blanks) in columns 1–8 and eight data fields of eight columns; in
//! large-field format the name carries a `*`, the data fields are sixteen columns wide, four per
//! line, and each continuation line starts with `*`. Continuations are automatic: the next line
//! continues the entry when its first field is blank (small) or `*` (large), so no continuation
//! markers are written in field 10. A data stream is the same in both formats: field `k` of an
//! entry sits at the same place in the stream whichever width carries it.
//!
//! Entries that hold only integers and keywords use small fields (labels stop at 99 999 999, eight
//! digits). Entries that hold a real number use large fields, because eight columns keep at most
//! seven significant digits. A real is written exactly when its shortest round-trip form fits
//! sixteen columns (every hand-entered value and coordinates on decimal grids); otherwise it is
//! rounded to the nearest value that fits, which keeps at least ten significant digits and, for
//! magnitudes between 1e-5 and 1e9 without a sign, fourteen. Free-field format would not help:
//! readers round free-field reals to the same widths.
use std::fmt::Write as _;
use crate::{Error, Result};
/// Columns of a small field.
const SMALL: usize = 8;
/// Columns of a large field.
const LARGE: usize = 16;
/// One data field.
#[derive(Debug, Clone, PartialEq)]
pub(crate) enum Field {
Blank,
Int(i64),
Real(f64),
Text(&'static str),
}
impl From<u32> for Field {
fn from(v: u32) -> Field {
Field::Int(v.into())
}
}
impl From<f64> for Field {
fn from(v: f64) -> Field {
Field::Real(v)
}
}
impl From<&'static str> for Field {
fn from(v: &'static str) -> Field {
Field::Text(v)
}
}
/// A bulk data entry: a name and its data fields in order (fields 2–9 of the first line, then
/// fields 2–9 of each continuation).
#[derive(Debug, Clone, PartialEq)]
pub(crate) struct Card {
name: &'static str,
fields: Vec<Field>,
}
impl Card {
pub(crate) fn new(name: &'static str) -> Card {
Card { name, fields: Vec::new() }
}
pub(crate) fn int(mut self, v: impl Into<i64>) -> Card {
self.fields.push(Field::Int(v.into()));
self
}
pub(crate) fn ints<I: Into<i64>>(mut self, v: impl IntoIterator<Item = I>) -> Card {
self.fields.extend(v.into_iter().map(|i| Field::Int(i.into())));
self
}
pub(crate) fn real(mut self, v: f64) -> Card {
self.fields.push(Field::Real(v));
self
}
pub(crate) fn reals(mut self, v: impl IntoIterator<Item = f64>) -> Card {
self.fields.extend(v.into_iter().map(Field::Real));
self
}
pub(crate) fn text(mut self, v: &'static str) -> Card {
self.fields.push(Field::Text(v));
self
}
pub(crate) fn blank(mut self) -> Card {
self.fields.push(Field::Blank);
self
}
/// An optional field: blank when absent.
pub(crate) fn opt(mut self, v: Option<impl Into<Field>>) -> Card {
self.fields.push(v.map_or(Field::Blank, Into::into));
self
}
pub(crate) fn name(&self) -> &'static str {
self.name
}
/// Blank fields up to the end of the current line, so the next field starts a continuation.
pub(crate) fn end_line(mut self) -> Card {
while !self.fields.len().is_multiple_of(8) {
self.fields.push(Field::Blank);
}
self
}
/// Append the entry to `out`. Trailing blank fields are dropped, and so are trailing blanks on
/// each line.
pub(crate) fn write(&self, out: &mut String) -> Result<()> {
let large = self.fields.iter().any(|f| matches!(f, Field::Real(_)));
let (width, per_line) = if large { (LARGE, 4) } else { (SMALL, 8) };
let used = self.fields.iter().rposition(|f| *f != Field::Blank).map_or(0, |i| i + 1);
let too_wide = |text: &dyn std::fmt::Display| Error::Limit(format!("{}: `{text}` does not fit a {width}-column field", self.name));
let mut lines = self.fields.get(..used).unwrap_or_default().chunks(per_line).peekable();
let mut first = true;
loop {
let start = out.len();
if first {
out.push_str(self.name);
}
if large {
out.push('*');
}
while out.len() < start + SMALL {
out.push(' ');
}
for f in lines.next().unwrap_or_default() {
match *f {
Field::Blank => out.extend(std::iter::repeat_n(' ', width)),
Field::Int(v) if digits(v) <= width => {
let _ = write!(out, "{v:>width$}");
}
Field::Int(v) => return Err(too_wide(&v)),
Field::Text(t) if t.len() <= width => {
let _ = write!(out, "{t:>width$}");
}
Field::Text(t) => return Err(too_wide(&t)),
Field::Real(v) => {
let (text, _) = real(v, width).ok_or_else(|| Error::Limit(format!("{}: {v} is not a finite number", self.name)))?;
let _ = write!(out, "{text:>width$}");
}
}
}
out.truncate(start + out.get(start..).map_or(0, |l| l.trim_end().len()));
out.push('\n');
first = false;
if lines.peek().is_none() {
return Ok(());
}
}
}
}
/// Characters of an integer written in decimal.
fn digits(v: i64) -> usize {
let sign = usize::from(v < 0);
sign + v.unsigned_abs().checked_ilog10().map_or(1, |l| l as usize + 1)
}
/// A finite real in at most `width` columns, and whether it is exact (reads back as the same
/// `f64`). `None` for NaN and infinities.
///
/// Forms, in order of preference: plain decimal with a leading digit (`0.3`, `210000.`) for
/// magnitudes from 1e-5 below 1e16; an exponent with `E` (`7.85E-9`); the exponent without `E` (`7.85-9`);
/// a plain decimal without its leading zero (`.0001`). When none fits the shortest round-trip
/// digits, the value is rounded to fewer significant digits until one does.
pub(crate) fn real(v: f64, width: usize) -> Option<(String, bool)> {
if !v.is_finite() {
return None;
}
if v == 0.0 {
return Some(("0.".to_string(), true));
}
let (digits, exp) = shortest(v.abs());
if let Some(s) = fit(v < 0.0, &digits, exp, width) {
return Some((s, true));
}
for keep in (1..digits.len()).rev() {
let rounded: f64 = format!("{:.*e}", keep - 1, v.abs()).parse().ok()?;
let (digits, exp) = shortest(rounded);
if let Some(s) = fit(v < 0.0, &digits, exp, width) {
return Some((s, false));
}
}
None
}
/// The shortest round-trip significant digits of a positive finite number, and the decimal
/// exponent of the first digit (`v = d.ddd × 10^exp`).
fn shortest(v: f64) -> (String, i32) {
let s = format!("{v:e}");
let (mantissa, exp) = s.split_once('e').unwrap_or((&s, "0"));
(mantissa.replace('.', ""), exp.parse().unwrap_or(0))
}
/// The first form of `±d.ddd × 10^exp` that fits `width` (lengths are worked out before
/// anything is formatted).
fn fit(negative: bool, digits: &str, exp: i32, width: usize) -> Option<String> {
let sign = if negative { "-" } else { "" };
let n = digits.len();
let e = exp.unsigned_abs() as usize;
let exp_len = e.checked_ilog10().map_or(1, |l| l as usize + 1);
// Plain decimal: the integer digits (padded with zeros), or zeros after the point.
let plain_len = |leading_zero: bool| sign.len() + if exp >= 0 { n.max(e + 1) + 1 } else { usize::from(leading_zero) + 1 + (e - 1) + n };
let plain = |leading_zero: bool| {
if exp >= 0 {
match digits.split_at_checked(e + 1) {
Some((a, b)) => format!("{sign}{a}.{b}"),
None => format!("{sign}{digits}{}.", "0".repeat(e + 1 - n)),
}
} else {
let zero = if leading_zero { "0" } else { "" };
format!("{sign}{zero}.{}{digits}", "0".repeat(e - 1))
}
};
let scientific = |with_e: bool| {
let (first, rest) = digits.split_at(1.min(n));
let marker = if with_e { "E" } else { "" };
let exp_sign = if exp < 0 { '-' } else { '+' };
format!("{sign}{first}.{rest}{marker}{exp_sign}{e}")
};
let sci_len = sign.len() + n + 1 + 1 + exp_len;
if (-5..16).contains(&exp) && plain_len(true) <= width {
Some(plain(true))
} else if sci_len < width {
Some(scientific(true))
} else if sci_len <= width {
Some(scientific(false))
} else if exp < 0 && plain_len(false) <= width {
Some(plain(false))
} else {
None
}
}
#[cfg(test)]
mod tests {
use super::*;
/// Read a real the way a Nastran reader does: an exponent may come without `E`.
fn read(s: &str) -> f64 {
let s = s.trim();
let split = s.char_indices().skip(1).find(|(i, c)| (*c == '+' || *c == '-') && !s[..*i].ends_with(['E', 'e']));
let normal = match split {
Some((i, _)) => format!("{}E{}", &s[..i], &s[i..]),
None => s.to_string(),
};
normal.parse().unwrap()
}
#[test]
fn reals_take_the_plainest_form_that_fits() {
let cases = [
(0.0, "0."),
(-0.0, "0."),
(0.3, "0.3"),
(-1.5, "-1.5"),
(210000.0, "210000."),
(7.85e-9, "7.85E-9"),
(1e-5, "0.00001"),
(1e20, "1.E+20"),
(-2.5e-300, "-2.5E-300"),
(123456789.12345, "123456789.12345"),
(f64::MAX, "1.7976931348623157E+308"),
];
for (v, want) in cases {
let (s, exact) = real(v, 32).unwrap();
assert_eq!(s, want, "{v}");
assert!(exact);
assert_eq!(read(&s), v);
}
assert_eq!(real(f64::NAN, 16), None);
assert_eq!(real(f64::INFINITY, 16), None);
// Tight widths fall back to the E-less exponent, then to fewer digits.
assert_eq!(real(1.25e-12, 7).unwrap(), ("1.25-12".into(), true));
assert_eq!(real(1.0 / 3.0, 8).unwrap(), (".3333333".into(), false));
}
#[test]
fn sixteen_columns_round_trip_short_values_and_keep_ten_digits_of_any() {
let mut seed = 0x9e37_79b9_7f4a_7c15_u64;
let mut next = || {
seed ^= seed << 13;
seed ^= seed >> 7;
seed ^= seed << 17;
seed
};
for _ in 0..20_000 {
let v = f64::from_bits(next());
if !v.is_finite() {
continue;
}
let (s, exact) = real(v, LARGE).unwrap();
assert!(s.len() <= LARGE, "{s}");
let back = read(&s);
if exact {
assert_eq!(back.to_bits(), v.to_bits(), "{v} -> {s}");
}
assert!(((back - v) / v).abs() < 1e-9 || v == 0.0, "{v} -> {s}");
// Coordinates and moduli in everyday ranges keep fourteen digits.
let w = (next() as f64 / u64::MAX as f64) * 1e9;
let (s, _) = real(w, LARGE).unwrap();
assert!(((read(&s) - w) / w).abs() < 1e-13 || w == 0.0, "{w} -> {s}");
}
for v in [0.1 + 0.2, 1.0 / 3.0, std::f64::consts::PI * 1e-7, -2.0f64.sqrt() * 1e5] {
let (s, _) = real(v, LARGE).unwrap();
assert!(((read(&s) - v) / v).abs() < 1e-13, "{v} -> {s}");
}
}
#[test]
fn cards_wrap_and_trim() {
let mut out = String::new();
Card::new("CHEXA").ints(1..=22u32).write(&mut out).unwrap();
Card::new("GRID").int(7).blank().reals([1.0, -2.5, 1.0 / 3.0]).write(&mut out).unwrap();
Card::new("PSHELL").int(1).int(2).real(0.5).blank().blank().write(&mut out).unwrap();
let want = "\
CHEXA 1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
17 18 19 20 21 22
GRID* 7 1. -2.5
* .333333333333333
PSHELL* 1 2 0.5
";
assert_eq!(out, want);
assert!(Card::new("X").int(123_456_789).write(&mut out).is_err(), "nine digits do not fit");
assert!(Card::new("X").real(f64::NAN).write(&mut out).is_err());
}
}
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//! Nastran bulk data: the model as an input file for a linear static (SOL 101) or normal modes
//! (SOL 103) run, written from the public Quick Reference Guide in our own words.
//!
//! A deck has three parts: executive control (the solution sequence), case control (one subcase
//! per step, selecting its constraint set, load set or eigenvalue method and its output) and bulk
//! data (the entries). What the model holds becomes:
//!
//! - nodes and reference points: `GRID`;
//! - solids: `CTETRA` (tet4, tet10), `CPENTA` (wedge6), `CHEXA` (hex8, hex20) with `PSOLID`;
//! shells: `CTRIA3`, `CQUAD4`, `CTRIA6`, `CQUAD8` with `PSHELL`; beams: `CBEAM` with `PBEAML`;
//! rods: `CROD` with `PROD`. Nastran numbers a 20-node hexahedron's mid-side nodes bottom
//! edges, vertical edges, top edges, where the model has bottom, top, vertical
//! ([`grids`] reorders them); every other kind keeps the model's order;
//! - the element formulation: `PSOLID`'s integration network and scheme (see [`solid_rule`]);
//! formulations Nastran's linear elements have no counterpart for are reported, not
//! approximated;
//! - isotropic materials: `MAT1`; orthotropic engineering constants: `MAT9` (the stiffness matrix
//! in the basic axes) for solids and `MAT8` for shells lying in planes of constant Z, with the
//! material X axis tied to the basic X axis through a `CORD2R`;
//! - boundary conditions: per step, one constraint set of `SPC1` (held degrees of freedom) and
//! `SPC` (prescribed values); in a modes step every constrained degree of freedom is held;
//! - forces, moments and tractions: `FORCE` and `MOMENT` at the nodal values the model resolves,
//! so every writer and the solver share one distribution; pressure: `PLOAD4` per element face;
//! gravity: `GRAV`; a step with several loads combines them with `LOAD`;
//! - kinematic coupling: `RBE2` (the reference point independent); distributing coupling: `RBE3`
//! (equal weights on the set's translations; the reference point dependent);
//! - frequency steps: `EIGRL` (Lanczos) with the step's mode count and range.
//!
//! Field widths, continuations and number forms are in [`card`]. Model content Nastran cannot
//! express is reported as [`Error::Unsupported`], every item at once, and nothing is written.
//! The same model always gives the same bytes.
mod card;
use std::collections::{BTreeMap, BTreeSet};
use std::fmt::Write as _;
use modelcraft_model::{
BeamProfile, Coupling, CouplingKind, Dofs, Elastic, ElementKind, Formulation, Integration, Load, MAX_LABEL, Model, OutputVariable, Procedure,
Resolved, SectionKind, Step,
};
use crate::{Error, Result};
use card::Card;
/// The format's name in errors.
pub const FORMAT: &str = "Nastran";
/// Most `GRAV` entries one run may select.
const MAX_GRAV: usize = 9;
/// Grids per `SPC1` entry; longer lists are split over entries of the same set.
const SPC1_GRIDS: usize = 1000;
/// The model as a Nastran deck, with every step (a deck of some steps:
/// [`crate::Format::write_steps`]).
pub fn write(model: &Model) -> Result<String> {
write_resolved(model, &model.resolve()?)
}
/// [`write`] for a model already resolved.
pub fn write_resolved(model: &Model, r: &Resolved) -> Result<String> {
let mut deck = Deck::new(model, r, model.steps().iter().collect());
deck.plan()?;
deck.emit()
}
/// The Nastran grid order of an element's nodes (model order in, Nastran order out).
pub fn grids(kind: ElementKind, nodes: &[u32]) -> impl Iterator<Item = u32> + '_ {
order(kind).iter().filter_map(|&i| nodes.get(i).copied())
}
/// For each Nastran grid position, the position in the model's node list.
pub fn order(kind: ElementKind) -> &'static [usize] {
const IDENTITY: [usize; 20] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19];
// Model: 9–12 bottom edges, 13–16 top edges, 17–20 vertical edges. Nastran: bottom, vertical, top.
const HEX20: [usize; 20] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 16, 17, 18, 19, 12, 13, 14, 15];
match kind {
ElementKind::Hex20 => &HEX20,
k => IDENTITY.get(..k.node_count()).unwrap_or(&IDENTITY),
}
}
/// The connection entry's name for an element kind.
pub fn element_card(kind: ElementKind) -> &'static str {
match kind {
ElementKind::Rod2 => "CROD",
ElementKind::Beam2 => "CBEAM",
ElementKind::Tri3 => "CTRIA3",
ElementKind::Tri6 => "CTRIA6",
ElementKind::Quad4 => "CQUAD4",
ElementKind::Quad8 => "CQUAD8",
ElementKind::Tet4 | ElementKind::Tet10 => "CTETRA",
ElementKind::Wedge6 => "CPENTA",
ElementKind::Hex8 | ElementKind::Hex20 => "CHEXA",
}
}
/// `PSOLID`'s integration network (`IN`) and scheme (`ISOP`) for an element kind and
/// formulation, or why Nastran has none.
///
/// - Full integration is the standard isoparametric rule: two points per direction for linear
/// kinds, three for quadratic ones (`TWO`/`THREE`, `FULL`).
/// - Reduced integration of a 20-node hexahedron is the 2 × 2 × 2 standard rule.
/// - Incompatible modes of an 8-node hexahedron are Nastran's bubble functions (`BUBBLE`, with
/// its default reduced-shear scheme).
/// - One-point reduced integration of linear solids (with hourglass control) and the hybrid
/// (displacement–pressure) formulation have no linear Nastran counterpart.
pub fn solid_rule(kind: ElementKind, f: Formulation) -> std::result::Result<(Option<&'static str>, Option<&'static str>), String> {
if f.hybrid {
return Err("the hybrid (displacement–pressure) formulation".into());
}
let quadratic = kind.is_quadratic();
match (kind, f.incompatible_modes, f.integration) {
(ElementKind::Hex8, true, _) => Ok((Some("BUBBLE"), None)),
(_, true, _) => Err(format!("incompatible modes on {} elements", kind.name())),
(ElementKind::Hex20, false, Integration::Reduced) => Ok((Some("TWO"), Some("FULL"))),
(_, false, Integration::Reduced) => Err(format!("reduced integration of {} elements", kind.name())),
(_, false, Integration::Full) if quadratic => Ok((Some("THREE"), Some("FULL"))),
(_, false, Integration::Full) => Ok((Some("TWO"), Some("FULL"))),
}
}
/// The stiffness of orthotropic engineering constants for Nastran's `MAT9`, as
/// `[[C11, C12, C13], [C22, C23, C33], [G12, G23, G13]]` (the normal block's upper triangle, then
/// the shear moduli for xy, yz and zx in `MAT9`'s order), or `None` when it is not finite.
pub fn orthotropic_stiffness(young: [f64; 3], poisson: [f64; 3], shear: [f64; 3]) -> Option<[[f64; 3]; 3]> {
let [e1, e2, e3] = young;
let [n12, n13, n23] = poisson;
// Compliance of the normal block (symmetric: ν_ij / E_i = ν_ji / E_j).
let (s11, s22, s33) = (1.0 / e1, 1.0 / e2, 1.0 / e3);
let (s12, s13, s23) = (-n12 / e1, -n13 / e1, -n23 / e2);
let det = s11 * (s22 * s33 - s23 * s23) - s12 * (s12 * s33 - s23 * s13) + s13 * (s12 * s23 - s22 * s13);
let c = [
[(s22 * s33 - s23 * s23) / det, (s13 * s23 - s12 * s33) / det, (s12 * s23 - s13 * s22) / det],
[0.0, (s11 * s33 - s13 * s13) / det, (s12 * s13 - s11 * s23) / det],
[0.0, 0.0, (s11 * s22 - s12 * s12) / det],
];
let [g12, g13, g23] = shear;
let out = [[c[0][0], c[0][1], c[0][2]], [c[1][1], c[1][2], c[2][2]], [g12, g23, g13]];
out.iter().flatten().all(|v| v.is_finite()).then_some(out)
}
/// Nastran's component code of a set of degrees of freedom, such as 123 or 156.
fn component(dofs: Dofs) -> i64 {
dofs.list().into_iter().fold(0, |c, d| c * 10 + i64::from(d))
}
/// The next identification number of a counter.
fn next_id(counter: &mut u32) -> Result<u32> {
let id = *counter;
if id > MAX_LABEL {
return Err(Error::Limit(format!("more than {MAX_LABEL} identification numbers of one kind")));
}
*counter += 1;
Ok(id)
}
/// The id of `value` in `list`, adding it under a new id from `counter` when it is not there.
fn intern<T: PartialEq>(list: &mut Vec<(u32, T)>, counter: &mut u32, value: T) -> Result<u32> {
if let Some((id, _)) = list.iter().find(|(_, v)| *v == value) {
return Ok(*id);
}
let id = next_id(counter)?;
list.push((id, value));
Ok(id)
}
/// A material's entry identification numbers.
#[derive(Debug, Clone, Copy, Default)]
struct MaterialIds {
/// `MAT1`, for isotropic materials (every element kind).
isotropic: Option<u32>,
/// `MAT9`, for orthotropic materials of solids.
solid: Option<u32>,
/// `MAT8`, for orthotropic materials of shells.
shell: Option<u32>,
}
/// Which element families use a material.
#[derive(Debug, Clone, Copy, Default)]
struct MaterialUse {
solid: bool,
shell: bool,
line: bool,
}
/// One property entry, and what its elements' connection entries need besides their nodes.
enum Property {
Solid { mid: u32, rule: (Option<&'static str>, Option<&'static str>) },
Shell { mid: u32, thickness: f64, offset: Option<f64>, mcid: Option<u32> },
Beam { mid: u32, profile: BeamProfile, orientation: [f64; 3] },
Rod { mid: u32, area: f64 },
}
/// A constraint set: per node, the prescribed value of each degree of freedom.
type Constraints = BTreeMap<u32, [Option<f64>; 6]>;
/// One step's subcase: the sets it selects.
struct Subcase<'m> {
step: &'m Step,
spc: Option<u32>,
load: Option<u32>,
method: Option<u32>,
}
struct Deck<'m> {
model: &'m Model,
r: &'m Resolved,
sol: u32,
subcases: Vec<Subcase<'m>>,
/// Everything the format cannot express.
problems: BTreeSet<String>,
next_sid: u32,
/// Material name → ids.
materials: BTreeMap<&'m str, MaterialIds>,
/// The coordinate system tying shell material axes to the basic axes, when one is needed.
material_csys: Option<u32>,
/// Properties in id order (id = position + 1), with their section's name.
properties: Vec<(&'m str, Property)>,
/// Element → property id.
element_pid: BTreeMap<u32, u32>,
/// Rigid elements: (id, coupling name, coupling).
rigid: Vec<(u32, &'m str, &'m Coupling)>,
/// Node → (dependent degrees of freedom, coupling that makes them dependent).
dependent: BTreeMap<u32, (Dofs, &'m str)>,
/// Constraint sets by id.
spc_sets: Vec<(u32, Constraints)>,
/// Load name → load set id.
load_sids: BTreeMap<&'m str, u32>,
/// Combinations: (id, load set ids).
combinations: Vec<(u32, Vec<u32>)>,
}
/// The solution sequence of a list of steps, or why there is none.
fn solution(steps: &[&Step]) -> std::result::Result<u32, String> {
let statics = steps.iter().find(|s| matches!(s.procedure, Procedure::Static {}));
let modes = steps.iter().find(|s| matches!(s.procedure, Procedure::Frequency { .. }));
match (statics, modes) {
(Some(_), None) => Ok(101),
(None, Some(_)) => Ok(103),
(Some(s), Some(m)) => Err(format!(
"one run solves either static steps (SOL 101) or frequency steps (SOL 103), and step `{}` is static while step `{}` extracts frequencies; write them as separate decks (choose the steps to write)",
s.name, m.name
)),
(None, None) => Err("there is no step to write".into()),
}
}
impl<'m> Deck<'m> {
fn new(model: &'m Model, r: &'m Resolved, steps: Vec<&'m Step>) -> Deck<'m> {
let mut problems = BTreeSet::new();
let sol = solution(&steps).unwrap_or_else(|p| {
problems.insert(p);
0
});
Deck {
model,
r,
sol,
subcases: steps.into_iter().map(|step| Subcase { step, spc: None, load: None, method: None }).collect(),
problems,
next_sid: 1,
materials: BTreeMap::new(),
material_csys: None,
properties: Vec::new(),
element_pid: BTreeMap::new(),
rigid: Vec::new(),
dependent: BTreeMap::new(),
spc_sets: Vec::new(),
load_sids: BTreeMap::new(),
combinations: Vec::new(),
}
}
fn plan(&mut self) -> Result<()> {
self.plan_materials();
self.plan_sections()?;
self.plan_couplings()?;
self.plan_constraints()?;
self.plan_loads()?;
for sub in &mut self.subcases {
if matches!(sub.step.procedure, Procedure::Frequency { .. }) {
sub.method = Some(next_id(&mut self.next_sid)?);
}
}
crate::unsupported(FORMAT, std::mem::take(&mut self.problems))
}
/// Material ids, for the forms the sections need.
fn plan_materials(&mut self) {
let model = self.model;
let mut uses: BTreeMap<&str, MaterialUse> = BTreeMap::new();
for s in model.sections().values() {
let u = uses.entry(s.material.as_str()).or_default();
match s.kind {
SectionKind::Solid {} => u.solid = true,
SectionKind::Shell { .. } => u.shell = true,
SectionKind::Beam { .. } | SectionKind::Rod { .. } => u.line = true,
}
}
let mut next_mid = 1u32;
let mut take = |wanted: bool| {
wanted.then(|| {
next_mid += 1;
next_mid - 1
})
};
for (name, u) in uses {
let ids = match model.material(name).and_then(|m| m.elastic) {
Some(Elastic::Isotropic { .. }) => MaterialIds { isotropic: take(true), ..MaterialIds::default() },
Some(Elastic::EngineeringConstants { .. }) => {
if u.line {
self.problems
.insert(format!("material `{name}`: orthotropic constants on beams or rods (their properties take isotropic materials)"));
}
MaterialIds { solid: take(u.solid), shell: take(u.shell), ..MaterialIds::default() }
}
None => MaterialIds::default(),
};
self.materials.insert(name, ids);
}
}
/// A new property for `elements`.
fn add_property(&mut self, section: &'m str, property: Property, elements: impl IntoIterator<Item = u32>) -> Result<()> {
self.properties.push((section, property));
let pid = u32::try_from(self.properties.len()).ok().filter(|p| *p <= MAX_LABEL).ok_or_else(|| Error::Limit("too many properties".into()))?;
for e in elements {
self.element_pid.insert(e, pid);
}
Ok(())
}
/// Properties and each element's property.
fn plan_sections(&mut self) -> Result<()> {
let (model, r) = (self.model, self.r);
for (sname, sec) in model.sections() {
let ids = self.materials.get(sec.material.as_str()).copied().unwrap_or_default();
let elements = r.sets.get(&sec.set).map(|s| s.elements.as_slice()).unwrap_or_default();
let kind_of = |e: u32| model.element(e).map(|el| el.kind);
match sec.kind {
SectionKind::Solid {} => {
let Some(mid) = ids.isotropic.or(ids.solid) else { continue };
// One property per integration rule the section's element kinds need.
let kinds: BTreeSet<ElementKind> = elements.iter().filter_map(|e| kind_of(*e)).collect();
let mut rules = BTreeMap::new();
for kind in kinds {
match solid_rule(kind, sec.formulation) {
Ok(rule) => {
rules.entry(rule).or_insert_with(Vec::new).push(kind);
}
Err(why) => {
self.problems.insert(format!("section `{sname}`: {why} (Nastran's linear solids have no such formulation)"));
}
}
}
for (rule, kinds) in rules {
let members = elements.iter().copied().filter(|e| kind_of(*e).is_some_and(|k| kinds.contains(&k)));
self.add_property(sname, Property::Solid { mid, rule }, members)?;
}
}
SectionKind::Shell { thickness, offset, points } => {
if sec.formulation.integration == Integration::Reduced {
self.problems.insert(format!("section `{sname}`: reduced integration of shells (Nastran's shells have one formulation)"));
}
if points < 2 {
self.problems.insert(format!(
"section `{sname}`: one integration point through the thickness (no bending stiffness; Nastran integrates a linear section exactly)"
));
}
let (mid, mcid) = match ids {
MaterialIds { isotropic: Some(m), .. } => (m, None),
MaterialIds { shell: Some(m), .. } => {
if !elements.iter().all(|e| model.element(*e).is_some_and(|el| self.in_constant_z(&el.nodes, el.kind))) {
self.problems.insert(format!(
"section `{sname}`: orthotropic shells that do not lie in planes of constant Z (the material axes are the global ones)"
));
}
(m, Some(*self.material_csys.get_or_insert(1)))
}
_ => continue,
};
// The nodes lie on the reference surface; Nastran's offset runs from them to
// the mid-surface along the element normal.
let offset = (offset != 0.0).then_some(-offset * thickness);
self.add_property(sname, Property::Shell { mid, thickness, offset, mcid }, elements.iter().copied())?;
}
SectionKind::Beam { profile, orientation } => {
let Some(mid) = ids.isotropic else { continue };
self.add_property(sname, Property::Beam { mid, profile, orientation }, elements.iter().copied())?;
}
SectionKind::Rod { area } => {
let Some(mid) = ids.isotropic else { continue };
self.add_property(sname, Property::Rod { mid, area }, elements.iter().copied())?;
}
}
}
Ok(())
}
/// Whether a shell element's corners lie in a plane of constant Z.
fn in_constant_z(&self, nodes: &[u32], kind: ElementKind) -> bool {
let corners = nodes.get(..kind.corner_count()).unwrap_or_default();
let mut z = corners.iter().map(|n| self.model.node(*n).map(|n| n.xyz[2]));
let first = z.next().flatten();
first.is_some() && z.all(|v| v == first)
}
/// Rigid element ids and the degrees of freedom couplings make dependent.
fn plan_couplings(&mut self) -> Result<()> {
let (model, r) = (self.model, self.r);
let mut next = model.elements().keys().next_back().copied().unwrap_or(0);
let mut overlaps: BTreeMap<(&str, &str), BTreeSet<u32>> = BTreeMap::new();
for (name, c) in model.couplings() {
next = next
.checked_add(1)
.filter(|n| *n <= MAX_LABEL)
.ok_or_else(|| Error::Limit(format!("coupling `{name}`: no element identification number left below {}", MAX_LABEL as u64 + 1)))?;
self.rigid.push((next, name.as_str(), c));
let dependents: &[u32] = match c.kind {
CouplingKind::Kinematic => r.sets.get(&c.set).map(|s| s.nodes.as_slice()).unwrap_or_default(),
CouplingKind::Distributing => r.reference_point_nodes.get(&c.reference_point).map(std::slice::from_ref).unwrap_or_default(),
};
for &node in dependents {
match self.dependent.get(&node).copied() {
Some((had, other)) if had.bits() & c.dofs.bits() != 0 => {
overlaps.entry((other, name.as_str())).or_default().insert(node);
}
Some((had, other)) => {
self.dependent.insert(node, (Dofs::from_bits(had.bits() | c.dofs.bits()), other));
}
None => {
self.dependent.insert(node, (c.dofs, name));
}
}
}
}
for ((a, b), nodes) in overlaps {
self.problems.insert(format!(
"couplings `{a}` and `{b}` both make nodes {} follow another node (Nastran makes a degree of freedom dependent once)",
labels(&nodes)
));
}
Ok(())
}
/// One constraint set per distinct step constraint, checked against coupled nodes.
fn plan_constraints(&mut self) -> Result<()> {
let (model, r) = (self.model, self.r);
// Conflicts, one problem per pair of definitions: the nodes they meet on.
let mut clashes: BTreeMap<(&str, &str, &str), BTreeSet<u32>> = BTreeMap::new();
let mut on_dependent: BTreeMap<(&str, &str), BTreeSet<u32>> = BTreeMap::new();
for sub in &mut self.subcases {
let step = sub.step;
let modes = matches!(step.procedure, Procedure::Frequency { .. });
let mut set: Constraints = BTreeMap::new();
let mut by: BTreeMap<(u32, u8), &str> = BTreeMap::new();
for name in &step.boundary_conditions {
let Some(bc) = model.boundary_condition(name) else { continue };
let dofs = bc.dofs();
// In a modes step every constrained degree of freedom is held.
let values: Vec<(u8, f64)> = dofs.list().into_iter().filter_map(|d| Some((d, if modes { 0.0 } else { bc.value(d)? }))).collect();
for &node in r.target_nodes(bc.target()) {
if let Some((dep, coupling)) = self.dependent.get(&node)
&& dep.bits() & dofs.bits() != 0
{
on_dependent.entry((name.as_str(), coupling)).or_default().insert(node);
}
let slots = set.entry(node).or_default();
for &(dof, value) in &values {
let Some(slot) = usize::from(dof).checked_sub(1).and_then(|i| slots.get_mut(i)) else { continue };
match *slot {
Some(v) if v != value => {
let other = by.get(&(node, dof)).copied().unwrap_or_default();
clashes.entry((step.name.as_str(), other, name.as_str())).or_default().insert(node);
}
_ => {
*slot = Some(value);
by.insert((node, dof), name);
}
}
}
}
}
if !set.is_empty() {
sub.spc = Some(intern(&mut self.spc_sets, &mut self.next_sid, set)?);
}
}
for ((step, a, b), nodes) in clashes {
self.problems.insert(format!(
"step `{step}`: boundary conditions `{a}` and `{b}` prescribe different values at nodes {} (Nastran takes one value per degree of freedom)",
labels(&nodes)
));
}
for ((bc, coupling), nodes) in on_dependent {
self.problems.insert(format!(
"boundary condition `{bc}` constrains nodes {} whose motion coupling `{coupling}` prescribes (Nastran cannot constrain a dependent degree of freedom)",
labels(&nodes)
));
}
Ok(())
}
/// Load set ids for the static steps' loads, and their combinations.
fn plan_loads(&mut self) -> Result<()> {
let (model, r) = (self.model, self.r);
let mut gravity = 0usize;
for sub in &mut self.subcases {
if !matches!(sub.step.procedure, Procedure::Static {}) {
continue;
}
let mut sids = Vec::new();
for name in &sub.step.loads {
if let Some(sid) = self.load_sids.get(name.as_str()) {
sids.push(*sid);
continue;
}
let Some(load) = model.load(name) else { continue };
match load {
Load::BodyForce { .. } => {
self.problems.insert(format!("load `{name}`: a body force (Nastran has no force-per-volume load for these elements)"));
}
Load::Gravity { set: Some(s), .. } if r.sets.get(s).map(|s| s.elements.len()) != Some(model.elements().len()) => {
self.problems.insert(format!("load `{name}`: gravity on part of the model (set `{s}`); Nastran's gravity acts on all of it"));
}
Load::Gravity { .. } => gravity += 1,
_ => {}
}
let sid = next_id(&mut self.next_sid)?;
self.load_sids.insert(name.as_str(), sid);
sids.push(sid);
}
sub.load = match sids.as_slice() {
[] => None,
[one] => Some(*one),
_ => Some(intern(&mut self.combinations, &mut self.next_sid, sids)?),
};
}
if gravity > MAX_GRAV {
self.problems.insert(format!("{gravity} gravity loads (a run selects at most {MAX_GRAV})"));
}
Ok(())
}
fn emit(&self) -> Result<String> {
let mut out = String::new();
out.push_str("$ Nastran bulk data written by ModelCraft\n");
let _ = writeln!(out, "$ units: {}", self.model.units().label());
let _ = writeln!(out, "SOL {}\nCEND\nTITLE = ModelCraft model\nECHO = NONE", self.sol);
for (i, sub) in self.subcases.iter().enumerate() {
let _ = writeln!(out, "SUBCASE {}", i + 1);
let title: String = format!(" SUBTITLE = {}", sub.step.name).chars().take(72).collect();
let _ = writeln!(out, "{title}");
for (key, sid) in [("SPC", sub.spc), ("LOAD", sub.load), ("METHOD", sub.method)] {
if let Some(sid) = sid {
let _ = writeln!(out, " {key} = {sid}");
}
}
for v in &sub.step.output {
let request = match v {
OutputVariable::Displacement => "DISPLACEMENT",
OutputVariable::ReactionForce => "SPCFORCES",
OutputVariable::Stress => "STRESS",
OutputVariable::Strain => "STRAIN",
};
let _ = writeln!(out, " {request} = ALL");
}
}
out.push_str("BEGIN BULK\n");
Card::new("PARAM").text("POST").int(-1).write(&mut out)?;
Card::new("PARAM").text("AUTOSPC").text("YES").write(&mut out)?;
if self.sol == 103 {
// Consistent (coupled) mass, as the other formats use by default.
Card::new("PARAM").text("COUPMASS").int(1).write(&mut out)?;
}
self.emit_mesh(&mut out)?;
self.emit_constraints(&mut out)?;
self.emit_loads(&mut out)?;
if self.subcases.iter().any(|s| s.method.is_some()) {
comment(&mut out, "eigenvalue extraction");
}
for sub in &self.subcases {
if let (Some(sid), Procedure::Frequency { modes, min_hz, max_hz }) = (sub.method, sub.step.procedure) {
Card::new("EIGRL").int(sid).opt(min_hz).opt(max_hz).int(modes).write(&mut out)?;
}
}
out.push_str("ENDDATA\n");
Ok(out)
}
/// Grids, materials, properties, elements and couplings.
fn emit_mesh(&self, out: &mut String) -> Result<()> {
comment(out, "nodes");
for (label, node) in self.model.nodes() {
Card::new("GRID").int(*label).blank().reals(node.xyz).write(out)?;
}
if !self.model.reference_points().is_empty() {
comment(out, "reference points");
}
for (name, rp) in self.model.reference_points() {
comment(out, &format!("reference point {name}: GRID {}", rp.label));
Card::new("GRID").int(rp.label).blank().reals(rp.xyz).write(out)?;
}
if let Some(cid) = self.material_csys {
comment(out, "material axes of orthotropic shells: the basic axes");
Card::new("CORD2R").int(cid).blank().reals([0.0, 0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0]).write(out)?;
}
comment(out, "materials");
for (name, ids) in &self.materials {
let Some(m) = self.model.material(name) else { continue };
let rho = m.density;
let card = match (m.elastic, ids) {
(Some(Elastic::Isotropic { young, poisson }), MaterialIds { isotropic: Some(mid), .. }) => {
Some(Card::new("MAT1").int(*mid).real(young).blank().real(poisson).opt(rho))
}
_ => None,
};
if let (Some(Elastic::EngineeringConstants { young, poisson, shear }), Some(mid)) = (m.elastic, ids.solid) {
let [[c11, c12, c13], [c22, c23, c33], [g12, g23, g13]] = orthotropic_stiffness(young, poisson, shear)
.ok_or_else(|| Error::Limit(format!("material `{name}`: its stiffness is not a finite number")))?;
let card = Card::new("MAT9")
.int(mid)
.reals([c11, c12, c13, 0.0, 0.0, 0.0, c22, c23, 0.0, 0.0, 0.0, c33, 0.0, 0.0, 0.0, g12, 0.0, 0.0, g23, 0.0, g13])
.opt(rho);
write_named(out, &format!("material {name}"), mid, card)?;
}
if let (Some(Elastic::EngineeringConstants { young: [e1, e2, _], poisson: [nu12, ..], shear: [g12, g13, g23] }), Some(mid)) =
(m.elastic, ids.shell)
{
write_named(out, &format!("material {name}"), mid, Card::new("MAT8").int(mid).reals([e1, e2, nu12, g12, g13, g23]).opt(rho))?;
}
if let (Some(card), Some(mid)) = (card, ids.isotropic) {
write_named(out, &format!("material {name}"), mid, card)?;
}
}
comment(out, "properties");
for (pid, (section, p)) in (1u32..).zip(&self.properties) {
let card = match p {
Property::Solid { mid, rule: (network, scheme) } => Card::new("PSOLID").int(pid).int(*mid).blank().opt(*network).blank().opt(*scheme),
Property::Shell { mid, thickness, .. } => Card::new("PSHELL").int(pid).int(*mid).real(*thickness).int(*mid).blank().int(*mid),
Property::Beam { mid, profile, .. } => {
let (shape, dims) = beam_dimensions(*profile);
Card::new("PBEAML").int(pid).int(*mid).blank().text(shape).end_line().reals(dims)
}
Property::Rod { mid, area } => Card::new("PROD").int(pid).int(*mid).real(*area),
};
write_named(out, &format!("section {section}"), pid, card)?;
}
comment(out, "elements");
for (label, el) in self.model.elements() {
let Some(pid) = self.element_pid.get(label).copied() else { continue };
let Some((_, property)) = usize::try_from(pid).ok().and_then(|p| self.properties.get(p - 1)) else { continue };
let card = Card::new(element_card(el.kind)).int(*label).int(pid).ints(grids(el.kind, &el.nodes));
let card = match property {
Property::Beam { orientation, .. } => card.reals(self.beam_vector(&el.nodes, *orientation)),
// CQUAD8 has four corner thicknesses before the material axes and the offset.
Property::Shell { offset, mcid, .. } if el.kind == ElementKind::Quad8 => card.blank().blank().blank().blank().opt(*mcid).opt(*offset),
Property::Shell { offset, mcid, .. } => card.opt(*mcid).opt(*offset),
Property::Solid { .. } | Property::Rod { .. } => card,
};
card.write(out)?;
}
if !self.rigid.is_empty() {
comment(out, "couplings");
}
for (eid, name, c) in &self.rigid {
let rp = self.r.reference_point_nodes.get(&c.reference_point).copied().unwrap_or_default();
let nodes = self.r.sets.get(&c.set).map(|s| s.nodes.as_slice()).unwrap_or_default();
let card = match c.kind {
CouplingKind::Kinematic => Card::new("RBE2").int(*eid).int(rp).int(component(c.dofs)).ints(nodes.iter().copied()),
// Equal weights on the set's translations.
CouplingKind::Distributing => {
Card::new("RBE3").int(*eid).blank().int(rp).int(component(c.dofs)).real(1.0).int(123).ints(nodes.iter().copied())
}
};
write_named(out, &format!("coupling {name}"), *eid, card)?;
}
Ok(())
}
/// Constraint sets: held degrees of freedom by `SPC1`, prescribed values by `SPC`.
fn emit_constraints(&self, out: &mut String) -> Result<()> {
if !self.spc_sets.is_empty() {
comment(out, "boundary conditions");
}
for (sid, set) in &self.spc_sets {
for sub in self.subcases.iter().filter(|s| s.spc == Some(*sid)) {
comment(out, &format!("step {}: SPC {sid}", sub.step.name));
}
let mut held: BTreeMap<u8, Vec<u32>> = BTreeMap::new();
let mut prescribed = Vec::new();
for (node, values) in set {
let mut zero = 0u8;
// Nonzero values: one entry per value, with every degree of freedom it applies to.
let mut by_value: Vec<(f64, u8)> = Vec::new();
for (bit, v) in values.iter().enumerate().filter_map(|(i, v)| Some((1u8 << i, (*v)?))) {
match by_value.iter_mut().find(|(w, _)| *w == v) {
_ if v == 0.0 => zero |= bit,
Some((_, m)) => *m |= bit,
None => by_value.push((v, bit)),
}
}
if zero != 0 {
held.entry(zero).or_default().push(*node);
}
prescribed.extend(by_value.into_iter().map(|(v, m)| (*node, m, v)));
}
for (mask, nodes) in &held {
for chunk in nodes.chunks(SPC1_GRIDS) {
Card::new("SPC1").int(*sid).int(component(Dofs::from_bits(*mask))).ints(chunk.iter().copied()).write(out)?;
}
}
for (node, mask, value) in prescribed {
Card::new("SPC").int(*sid).int(node).int(component(Dofs::from_bits(mask))).real(value).write(out)?;
}
}
Ok(())
}
/// Load sets and their combinations.
fn emit_loads(&self, out: &mut String) -> Result<()> {
if !self.load_sids.is_empty() {
comment(out, "loads");
}
for (name, sid) in &self.load_sids {
let Some(load) = self.model.load(name) else { continue };
let entry = |card: Card, out: &mut String, first: &mut bool| -> Result<()> {
if std::mem::take(first) {
comment(out, &format!("load {name}: {} {sid}", card.name()));
}
card.write(out)
};
let mut first = true;
match load {
Load::Force { .. } | Load::Traction { .. } | Load::Moment { .. } => {
let card = if matches!(load, Load::Moment { .. }) { "MOMENT" } else { "FORCE" };
let values = self.r.nodal_loads.get(*name).map(Vec::as_slice).unwrap_or_default();
for (node, v) in values.iter().filter(|(_, v)| v.iter().any(|c| *c != 0.0)) {
entry(Card::new(card).int(*sid).int(*node).blank().real(1.0).reals(*v), out, &mut first)?;
}
}
Load::Pressure { set, magnitude } => {
for f in self.r.sets.get(set).map(|s| s.faces.as_slice()).unwrap_or_default() {
if let Some(card) = self.pressure(*sid, *f, *magnitude) {
entry(card, out, &mut first)?;
}
}
}
Load::Gravity { acceleration, .. } => entry(Card::new("GRAV").int(*sid).blank().real(1.0).reals(*acceleration), out, &mut first)?,
Load::BodyForce { .. } => {}
}
}
for (sid, loads) in &self.combinations {
let mut card = Card::new("LOAD").int(*sid).real(1.0);
for l in loads {
card = card.real(1.0).int(*l);
}
card.write(out)?;
}
Ok(())
}
/// A `PLOAD4` for one element face, positive pushing into the element.
fn pressure(&self, sid: u32, f: modelcraft_model::ElementFace, magnitude: f64) -> Option<Card> {
let el = self.model.element(f.element)?;
let card = Card::new("PLOAD4").int(sid).int(f.element);
if el.kind.dimension() == 2 {
// Nastran pushes along the element normal; face 1 is the side the normal points to.
let p = if f.face == 1 { -magnitude } else { magnitude };
return Some(card.real(p));
}
let corners = el.kind.corner_count();
let local = el.kind.faces().get(usize::from(f.face).checked_sub(1)?)?;
let face_corners = local.get(..local.iter().take_while(|&&i| i < corners).count())?;
let node = |i: usize| el.nodes.get(i).copied();
let card = card.real(magnitude).blank().blank().blank().int(node(*face_corners.first()?)?);
Some(match (el.kind, face_corners.len()) {
// Tetrahedra: the corner off the face.
(ElementKind::Tet4 | ElementKind::Tet10, _) => card.int(node((0..corners).find(|i| !face_corners.contains(i))?)?),
// Quadrilateral faces: the corner diagonally opposite G1.
(_, 4) => card.int(node(*face_corners.get(2)?)?),
// Triangular faces of wedges: G3 stays blank.
_ => card,
})
}
/// The `CBEAM` orientation vector: the profile's local 1 direction (the section's
/// orientation) is Nastran's element z axis, so v = axis × orientation.
fn beam_vector(&self, nodes: &[u32], o: [f64; 3]) -> [f64; 3] {
let p = |i: usize| nodes.get(i).and_then(|n| self.model.node(*n)).map(|n| n.xyz).unwrap_or_default();
let (a, b) = (p(0), p(1));
let t = [b[0] - a[0], b[1] - a[1], b[2] - a[2]];
[t[1] * o[2] - t[2] * o[1], t[2] * o[0] - t[0] * o[2], t[0] * o[1] - t[1] * o[0]]
}
}
/// `PBEAML`'s shape and dimensions. Nastran's sections have their height along the element y
/// axis and their width (flanges) along z, which [`Deck::beam_vector`] makes the profile's
/// local 1 direction.
fn beam_dimensions(p: BeamProfile) -> (&'static str, Vec<f64>) {
match p {
BeamProfile::Rectangle { width, height } => ("BAR", vec![width, height]),
BeamProfile::Circle { radius } => ("ROD", vec![radius]),
BeamProfile::Pipe { radius, thickness } if radius - thickness > 0.0 => ("TUBE", vec![radius, radius - thickness]),
BeamProfile::Pipe { radius, .. } => ("ROD", vec![radius]),
BeamProfile::I { height, width, web, flange } => ("I", vec![height, width, width, web, flange, flange]),
BeamProfile::Box { width, height, thickness } => ("BOX", vec![width, height, thickness, thickness]),
}
}
/// An entry preceded by a comment naming what it holds (`material Steel: MAT1 1`).
fn write_named(out: &mut String, what: &str, id: u32, card: Card) -> Result<()> {
comment(out, &format!("{what}: {} {id}", card.name()));
card.write(out)
}
/// The first few labels of a list, and how many more there are.
fn labels(nodes: &BTreeSet<u32>) -> String {
const SHOWN: usize = 5;
let shown: Vec<String> = nodes.iter().take(SHOWN).map(u32::to_string).collect();
match nodes.len().saturating_sub(SHOWN) {
0 => shown.join(", "),
more => format!("{}, and {more} more", shown.join(", ")),
}
}
/// A comment line, at most 80 columns.
fn comment(out: &mut String, text: &str) {
out.extend(format!("$ {text}").chars().take(80));
out.push('\n');
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn orthotropic_stiffness_of_isotropic_constants_is_lames() {
let (e, nu) = (210_000.0, 0.3);
let g = e / (2.0 * (1.0 + nu));
let c = orthotropic_stiffness([e; 3], [nu; 3], [g; 3]).unwrap();
let k = e / ((1.0 + nu) * (1.0 - 2.0 * nu));
let close = |a: f64, b: f64| (a - b).abs() < 1e-9 * b.abs();
assert!(close(c[0][0], k * (1.0 - nu)) && close(c[1][0], k * (1.0 - nu)) && close(c[1][2], k * (1.0 - nu)));
assert!(close(c[0][1], k * nu) && close(c[0][2], k * nu) && close(c[1][1], k * nu));
assert_eq!(c[2], [g; 3]);
}
#[test]
fn hex20_mid_side_nodes_swap_blocks() {
let nodes: Vec<u32> = (1..=20).collect();
let g: Vec<u32> = grids(ElementKind::Hex20, &nodes).collect();
assert_eq!(&g[..12], &nodes[..12]);
assert_eq!(&g[12..16], &[17, 18, 19, 20]);
assert_eq!(&g[16..], &[13, 14, 15, 16]);
for k in ElementKind::ALL {
let mut sorted = order(k).to_vec();
sorted.sort_unstable();
assert_eq!(sorted, (0..k.node_count()).collect::<Vec<_>>(), "{k:?} is a permutation");
}
}
#[test]
fn formulations_map_or_are_named() {
let f = |integration, incompatible_modes, hybrid| Formulation { integration, incompatible_modes, hybrid };
assert_eq!(solid_rule(ElementKind::Hex8, f(Integration::Full, false, false)), Ok((Some("TWO"), Some("FULL"))));
assert_eq!(solid_rule(ElementKind::Hex8, f(Integration::Full, true, false)), Ok((Some("BUBBLE"), None)));
assert_eq!(solid_rule(ElementKind::Hex20, f(Integration::Reduced, false, false)), Ok((Some("TWO"), Some("FULL"))));
assert_eq!(solid_rule(ElementKind::Tet10, f(Integration::Full, false, false)), Ok((Some("THREE"), Some("FULL"))));
assert!(solid_rule(ElementKind::Hex8, f(Integration::Reduced, false, false)).is_err());
assert!(solid_rule(ElementKind::Tet4, f(Integration::Full, false, true)).is_err());
}
}