In non-linear finite element analysis accurately capturing the material behavior is frequently of first order importance but is also the least well known input parameter. This is especially the case in critical fatigue analysis and high temperature applications where both relatively large strain ranges (first loading) and very small strain ranges (close to stabilization cycle) must be accurately known.
Many times there is a significant divide between the testing lab and the CAE department utilizing the material data for simulations. Hopefully that divide is only physical, but more often there is a conceptual gap between a material department’s objectives, techniques and experience compared with that of the CAE modeler. NW Numerics views mechanical testing as a true multi-disciplinary task, requiring significant transfer of knowledge between both mechanical engineers and material scientists.
Testing for characterization
For material model calibration efforts, it is often best to design a test matrix for a wide spectrum of loading conditions in order to maximize the validity of the material behavior while in service. It is almost always better to add different loading conditions than to duplicate any one case, because the material behavior is always viewed under the continuity of a constitutive model, and not measuring only a specific intrinsic individual parameter. In general, coming up with specific separable parameters, whose interactions can exist on any and every level, is not easy. NW Numerics specializes in test matrix design where each and every test provides a maximum amount of information for the constitutive modeler.
Testing for life prediction
The reason for performing nonlinear computations across a spectrum of loading and environmental conditions, is to predict life, forming failures and/or damage, all of which are important to the analyst and the designer. NW Numerics has a wide breadth of experience with fatigue testing and modeling, fractography analysis, crack growth testing, high temperature creep and environment effects, and ductile rupture testing. Our current testing capabilities and investment reflect this background.
Testing for the unusual
NW Numerics has a strong design team specializing in customized testing instrumentation and fixtures. Many components of our test frame load-trains, data acquisition software, extensometers, and other monitoring equipment are custom made in house. This experience and success in developing such testing processes implies that we are much less likely to have capability limitations, while ensuring very high quality.