A component can fail without ever carrying a heavy load. Heat it, cool it, heat it again, and if its expansion is restrained - by a bolted joint, by a neighbouring material, or simply by its own cooler interior - every cycle forces the material to strain a little, then unstrain, then strain again. No external force is pushing on it. The temperature swing alone is doing the work, and eventually a crack appears. Thermal fatigue analysis using FEA is how engineers predict where that crack will start and how many cycles it will take, before the part goes into service. Key takeaways Thermal fatigue is driven by restrained expansion and contraction, not external loading - the stress comes from the temperature change itself. The main drivers are constraint, temperature gradients through the part, and CTE mismatch between joined materials. It is usually a low-cycle fatigue problem involving cyclic plastic strain, so strain-life methods such as Coffin-Manson are the usual approach. ...
Run a linear FEA study on a component that bends, snaps or stretches significantly, and the software will still give you an answer - it just won't necessarily be the right one. Linear analysis assumes the structure's stiffness stays constant as it deforms, an assumption that quietly breaks down the moment deflection, rotation or strain moves beyond a small range. Large deformation analysis removes that assumption, recalculating geometry and stiffness as the structure actually changes shape under load - which is exactly what components like snap-fit clips, elastomer seals, thin sheet parts and cables need to be analysed honestly. Key takeaways Linear FEA assumes small deflections and constant stiffness - an assumption that breaks down for large rotations, large strains, or changing load paths. Geometric nonlinearity is one of three sources of nonlinear behaviour; material and contact nonlinearity often show up alongside it in the same component. Large deformation pro...