Non-linear Structural Analysis

Three types of non-linear analysis are currently available: non-linear separating contact, geometric non-linear, and material non-linear.

Types

Separating Contact
This analysis type provides a mechanism where parts may partially or completely separate from each other. When this happens, forces only transfer through the still connected portion of the connection. A friction coefficient is used to define the sticking/sliding threshold. Typical friction values are 0.1 to 0.2.
Geometric

To account for changes in geometry as the structure deforms, the strain-displacement and equilibrium equations are iteratively solved. Follower loads (loads that stay normal to the surface and the geometry deforms/rotates) can be optionally defined. This is considered a large displacement, small strain analysis. That is, while large deformations can be predicted, the material properties remain linear and plastic deformation is not considered. Typical uses for geometric non-linear analysis are predicting deformations in slender structures in aerospace, civil and mechanical engineering applications and stability (buckling) analyses of all types.

The prescribed load can be applied as the full load or incrementally. Incremental loading provides a load history with results at the specified number of load increments. This can be used for non-linear buckling analysis to determine the load at which structural instabilities may occur.

Material

Non-linear contains additional analysis operations where the solver must iterate to find the value of interest. Expect this to run slightly longer and as such, care should be taken to make sure the analysis defined makes sense physically.

Temperature dependent material

Coupled structural thermal analysis can be solved by activating the temperature dependent material option from the dialog. This will allow solving the analysis by utilizing the temperature curve included for elasticity-modulus, Poisson’s ratio, density and thermal expansion coefficient.

Notes

  1. Equivalent strain is calculated as:
    Eq. strain = sqrt 2/9 *  Ex - Ey 2  +  Ey -Ez 2  +  Ez-Ex 2  + 6 *  Exy 2  +  Eyz 2  +  Exz 2 MathType@MTEF@5@5@+= feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbiqaaGHbcaqGfb GaaeyCaiaab6cacaaMe8Uaae4CaiaabshacaqGYbGaaeyyaiaabMga caqGUbGaaGPaVlaab2dacaaMc8Uaae4CaiaabghacaqGYbGaaeiDam aabmaabaGaaeOmaiaab+cacaqG5aGaaGPaVlaabQcacaaMc8+aaeWa aeaadaqadaqaaiaabweacaqG4bGaaGPaVlaab2cacaaMc8Uaaeyrai aabMhaaiaawIcacaGLPaaadaahaaWcbeqaaiaabkdaaaGccaaMc8Ua ae4kaiaaykW7daqadaqaaiaabweacaqG5bGaaGPaVlaab2cacaqGfb GaaeOEaaGaayjkaiaawMcaamaaCaaaleqabaGaaeOmaaaakiaaykW7 caqGRaGaaGPaVpaabmaabaGaaeyraiaabQhacaqGTaGaaeyraiaabI haaiaawIcacaGLPaaadaahaaWcbeqaaiaabkdaaaGccaaMc8Uaae4k aiaaykW7caqG2aGaaGPaVlaabQcacaaMc8+aaeWaaeaacaqGfbGaae iEaiaabMhadaahaaWcbeqaaiaabkdaaaGccaaMc8Uaae4kaiaaykW7 caqGfbGaaeyEaiaabQhadaahaaWcbeqaaiaabkdaaaGccaaMc8Uaae 4kaiaaykW7caqGfbGaaeiEaiaabQhadaahaaWcbeqaaiaabkdaaaaa kiaawIcacaGLPaaaaiaawIcacaGLPaaaaiaawIcacaGLPaaaaaa@8CDA@
  2. The temperature curves are utilized only if the Temperature dependent properties option is checked in Structural setup. Otherwise, the non-zero nominal values are used.
  3. At present, only one temperature load can be linked from thermal analysis to a structural subcase when Temperature dependent properties is enabled.