Considering large deflections in panels - ESAComp 4.4 introduces nonlinear analysis

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In composite panels with large support spans, deflections are primarily due to bending. Out-of-plane shear can also play a significant role in sandwich structures. While these deformation types are considered in the typically used linear static analyses, the results are not accurate when going beyond the small deflections regime. When a panel is firmly fixed at its edges, it starts to carry loads partly like a membrane already at low load levels. The panel exhibits stress stiffening. Consequently, with an appropriate analysis approach more efficient structures can be designed.

 

Nonlinear panel analysis

The ESAComp image shows the load-deflection curve for a typical boat application using the linear and nonlinear FE analysis.

 

For accurate analyses of flat/curved panels and cylinders - including stiffened ones - the upcoming ESAComp 4.4 version introduces geometrically nonlinear static analysis. Besides static load response and failure, loads can be taken up to buckling and postbuckling region, which may reveal considerably different results than a linear buckling analysis. The analyses utilize the Elmer FE solver that is coupled with ESAComp. The new capability allows accurate nonlinear analyses with little effort already in the preliminary design phases, thus leading to lighter designs and material savings. Further, when there is need for performing analyses of the complete structure with general FE software, the ESAComp panel and cylinder analyses give a hint whether the geometric nonlinearities should be considered in those analyses as well.

The geometrically nonlinear panel analysis is a standard feature of ESAComp 4.4 that will be available to all users. The cylinder nonlinear analysis is available to those with the cylinder add-on module.

Further reading: ESAComp Example Case – Stress Stiffening