The vast majority of stress analyses assume material linearity where the ratio of stress to strain is a constant value (Young’s Modulus or Modulus of Elasticity). However, when the stress level in a component exceeds the yield strength of the material (for a ductile material) its stress-strain relation shape is no longer linear and the material moves into the plastic region. Stress levels exceeding the yield strength will be over-estimated when using a linear material model.
In certain design analyses, the material behaviour needs to be investigated when it becomes plastic. For example, the implications to structural integrity may need to be assessed when stress levels beyond the yield strength are predicted at certain locations in a linear analysis. Certain components are designed to operate in the plastic region (e.g. metal gasket seals) and therefore a non-linear analysis is required to simulate the stress and deformation accurately to give a valid assessment on whether the component is designed correctly.
Non-linear material analysis is typically modelled by using either multi-linear or bi-linear material models. For non-linear material analyses, the availability of the stress-strain curve for the relevant material is a pre-condition. TriVista Engineering has access to wide a range of stress-strain curves for many commonly used materials. FE analyses using non-linear material are likely to be more demanding on computing resources. With the progress in computing hardware and high performance computing (HPC), analyses using non-linear material models have become more realistic.
TriVista provide FEA consulting services and has a lot of experience in non-linear stress analysis using non-linear material model. If you would like to know more please feel free to call or email (contact details below). Our experienced engineers will be happy to help you. Alternatively, you may prefer to use our simple enquiry form.