Materials
deFlex includes a built-in material database with properties sourced from ASM, MatWeb, ASTM specifications, and manufacturer datasheets. Each material provides Young's modulus, Poisson's ratio, yield stress, density, thermal expansion coefficient, and hardening curves for nonlinear analysis.
Built-in materials
Polymers
| Property | ABS | TPU 95A |
|---|---|---|
| Category | Polymer | Polymer |
| Young's modulus (E) | 2,400 MPa | 26 MPa |
| Poisson's ratio (nu) | 0.38 | 0.48 |
| Yield stress | 44.0 MPa | 8.6 MPa |
| Ultimate tensile strength | 48.0 MPa | 35.0 MPa |
| Density | 1,050 kg/m^3 | 1,150 kg/m^3 |
| CTE | 90.0 x 10^-6 /K | 150.0 x 10^-6 /K |
| Endurance limit | 13.0 MPa | 5.0 MPa |
| Common | Yes | No |
ABS is the default material. Temperature-dependent data is available at 23, 50, and 80 degrees C for the nonlinear hardening curve.
TPU 95A is a flexible thermoplastic polyurethane suitable for compliant mechanism designs requiring large elastic deformations. Data sourced from BASF Elastollan / Polymaker PolyFlex datasheets and MatWeb.
Aluminum alloys
| Property | 6061-T6 | 7075-T6 |
|---|---|---|
| Young's modulus (E) | 68,900 MPa | 71,700 MPa |
| Poisson's ratio (nu) | 0.33 | 0.33 |
| Yield stress | 276.0 MPa | 503.0 MPa |
| Ultimate tensile strength | 310.0 MPa | 572.0 MPa |
| Density | 2,700 kg/m^3 | 2,810 kg/m^3 |
| CTE | 23.6 x 10^-6 /K | 23.4 x 10^-6 /K |
| Endurance limit | 96.5 MPa | 159.0 MPa |
| Common | Yes | No |
Steels
| Property | A36 | 304 Stainless | 4130 |
|---|---|---|---|
| Young's modulus (E) | 200,000 MPa | 193,000 MPa | 205,000 MPa |
| Poisson's ratio (nu) | 0.26 | 0.29 | 0.29 |
| Yield stress | 250.0 MPa | 215.0 MPa | 435.0 MPa |
| Ultimate tensile strength | 450.0 MPa | 505.0 MPa | 670.0 MPa |
| Density | 7,850 kg/m^3 | 8,000 kg/m^3 | 7,850 kg/m^3 |
| CTE | 11.7 x 10^-6 /K | 17.3 x 10^-6 /K | 12.2 x 10^-6 /K |
| Endurance limit | 225.0 MPa | 240.0 MPa | 335.0 MPa |
| Common | Yes | Yes | No |
Titanium
| Property | Ti-6Al-4V |
|---|---|
| Young's modulus (E) | 113,800 MPa |
| Poisson's ratio (nu) | 0.342 |
| Yield stress | 880.0 MPa |
| Ultimate tensile strength | 950.0 MPa |
| Density | 4,430 kg/m^3 |
| CTE | 8.6 x 10^-6 /K |
| Endurance limit | 510.0 MPa |
| Common | Yes |
Material properties explained
| Property | Symbol | Unit | Description |
|---|---|---|---|
| Young's modulus | E | MPa | Resistance to elastic deformation. Higher values mean stiffer material. |
| Poisson's ratio | nu | -- | Ratio of lateral strain to axial strain. Typical range 0.25 -- 0.40 for metals, up to 0.49 for rubber. |
| Yield stress | sigma_y | MPa | Stress at which permanent (plastic) deformation begins (0.2% offset). |
| Ultimate tensile strength | sigma_u | MPa | Maximum engineering stress before fracture. |
| Density | rho | kg/m^3 | Mass per unit volume. |
| Thermal expansion coefficient | alpha | 1/K | Fractional length change per degree of temperature change. Used by the decoupled flexure thermal stage. |
| Endurance limit | -- | MPa | Stress amplitude below which the material can sustain infinite fatigue cycles. |
How materials affect the solver
The solver distributes material between a solid phase (full material properties) and a void phase (near-zero stiffness). The optimizer works with relative stiffness values, so changing the material typically does not change the optimal design -- only the absolute force, displacement, and stress values scale.
Material choice matters when:
- Stress constraints are active. The yield stress determines the allowable stress limit.
- Nonlinear analysis is enabled. The hardening curve and constitutive model depend on the material.
- Thermal flexure analysis is used. The CTE determines thermal displacement directions at bolt pads.
- Post-optimization analysis is performed. Absolute displacement and force values depend on E and nu.
Custom materials
To use a material not in the database, leave the material selection empty and specify Young's modulus and Poisson's ratio directly in the analysis settings. Note that hardening curves, yield stress, and thermal properties will not be available for custom materials.
Data sources
- ABS: Supplier datasheet hardening curves, published range E = 2,000--2,600 MPa.
- TPU 95A: BASF Elastollan / Polymaker PolyFlex datasheets, MatWeb.
- Aluminum alloys: ASM Handbook, MatWeb, NASA Materials Data Handbook.
- Steels: ASTM specifications, MatWeb, MIL-HDBK-5J.
- Titanium: MatWeb, TIMET datasheets, MMPDS-01.
- All values at room temperature (23 degrees C) unless noted.