Optimizing correlation and leverage between digital simulation and physical test has long been a central challenge in product development and functional design verification and validation. Wolf Star Technologies is an engineering software and service provider that specializes in helping engineering organizations understand and overcome the “pitfalls of structural and dynamic issues that plague every product development project.” The company characterizes its unique strength as its “first-to-market solutions that meet the fundamental needs of how an engineer/analyst needs to work with their FEA tools.” Its software product offerings of True-Load, True-QSE and True-LDE “bring understanding to dynamic loading of structures and how to extract decision-ready data from FEA models.”
True-Load is a software solution that leverages FEA models to decide how best to place strain gauges on unmodified physical parts and then back-calculate loading. Output feeds directly into True-QSE, the company’s post-processing tool for “rapid virtual iteration.” True-Load directly interfaces to FEA fatigue software to make FEA-based fatigue calculation with correlated loading events “a natural part of the design cycle,” the company says.
- Create multi-channel load cells that leverage the user’s parts and FEA models.
- Determine optimal strain gauge placement from FEA model.
- Calculate load proportionality matrices.
- Use measured strains to back-calculate operating loads.
- Create quasi-static events to be used with True-QSE.
“One of the most challenging tasks for analysts is to develop load cases for their FEA model that match measured strain values,” the company observes. “Typically, it will take weeks to develop the right load cases that match just one or two strain gauges at a single point in time.”
True-Load “makes that situation a thing of the past.” True-Load will determine optimal gauge placement based on the FEA model. Once strains are collected at these optimal gauge locations, the strain data is read into True-Load to calculate load time histories that will typically match the measured strain to within 2% at every point in time, the company reports. “When combined with True-QSE, interrogating any point in the model for strain, stress or displacement is easy and interactive. Typically, it takes a few minutes to determine the strain gauge placement and a few minutes to back-calculate the loading profiles.”
True-QSE creates Quasi-Static Events by attaching user-defined scaling functions to FEA solutions. True-QSE “leverages the power of linear superposition.” Like True-LDE, True-QSE supports interaction with the FEA model to create plots of nodal and elemental functions. It can create operating deflection shapes, and performs linear superposition of FEA results via scaling functions to create nodal functions, elemental functions and full-field results.
Most structures behave linearly during their operational service events, Wolf Star notes, and the loading is usually a complex combination of individual loading events. True-QSE allows the analyst to understand the time-varying nature of the responses to known loading histories—the analytical equivalent of a multi-DOF laboratory test. True-QSE has tools to rapidly plot nodal and elemental functions and the ability to create full-field results in a new FEA database. No additional decompositions of the stiffness matrix are required: only an existing FEA database with unit load results and defined amplitude functions for input are required to generate complex results. Utilities to generate standard function types such as sine sweep, random, square wave and saw wave are supplied.
True-LDE is designed to make post-processing of Linear Dynamic Events intuitive and interactive. True-LDE leverages the power of linear superposition of modal results. Users can quickly probe the model for responses to user-defined excitations. True-LDE offers tools to create operating deflection shapes and peak-value plots.
True-LDE’s interactive linear dynamic event analysis supports:
- Time domain modal superposition.
- Deterministic frequency domain modal superposition.
- Random / PSD domain modal superposition.
With True-LDE the user can interactively create nodal functions, elemental functions and full-field results, and can optionally include the effects of pre-load on all results.
Linear dynamics is a critical part of understanding the real-world response of structures. The powerful FEA solutions of time domain, frequency domain and PSD domain provide critical calculation results. Unfortunately, examining the results in an interactive fashion is challenging within most FEA post-processors, Wolf Star notes.
The company says True-LDE solves this problem through an intuitive UI that allows the analyst to filter modes based on percent modal mass and modal participation function amplitude. The user can interactively query any node or element in the model for XY plots of the response. In addition, full-field results can be calculated for any subset of the time domain.
An important feature of True-LDE, Wolf Star says, is that the effects of pre-load can be optionally included in any of the calculations. This feature is available for the interface to FEA-based fatigue solvers as well. The influence of pre-load can be critical to calculating the durability of structures, and “no other linear dynamics tool provides an easy method for including pre-load the way True-LDE does.”