The nature of the load applied to a body is also important in understanding what type of structural mechanics analysis is required for a particular problem. Slowly applied or steady (quasi-static) loads on structures require less sophisticated analysis than dynamic, i.e. time-varying, loads. Dynamic loading brings the mass of a structure into the equation. Whether a load is “quasi-static” or dynamic depends on both the nature of the load and the type of structure. Knowing how to make the distinction between the two is key to getting an accurate answer to a structural mechanics problem. Structural analysis may also account for nonlinear response of both materials and geometry. Plasticity, crush of porous materials, and visco-elastic/visco-plastic effects are some of the phenomena that result in nonlinear material response. The need to account for nonlinear geometry is often driven by large deformations that create changes in stiffness and mass distribution relative to applied loads.

Advanced numerical tools must be used when structural analysis involves the full range of geometric, material, and loading complexity. These tools are typically based on the Finite Element Method (FEM). To solve a problem using FEM, the solid body geometry is created in CAD and then subdivided into a number of elements having fairly regular geometry. The resulting array of elements, or mesh, represents of sets of relatively simple equations that can be solved simultaneously for deformation and motion of a body given particular loads and boundary conditions. Using this numerical solution along with advanced material models allows the strain and stress states to be determined. This allows us to provide accurate answers to questions like: “Will it bend?”, “Will it break?”, “How much kinetic energy can it absorb?”.

Corvid’s Advantage
At Corvid Technologies we use advanced numerical tools to solve large-scale structural dynamics problems. Our indigenous computing capability gives us the ability to run very large problems (>5 million degrees of freedom). We utilize sophisticated material models and advanced techniques like mesh relaxation and material advection to provide predictive analysis for highly complex problems. Our researchers are experienced in conducting target/weapon interaction tests in parallel with analysis using advanced numerical tools. This two-pronged approach allows true insight into structural dynamics phenomena, and the ability to intelligently interpret the results of numerical analysis.

The combination of our structural dynamics, shock physics and CFD capabilities makes us uniquely qualified to tackle difficult problems such as blast-structure interaction and structural response due to hypervelocity impacts. Such problems are truly “multi-physics problems” and involve highly disparate time scales. Our structural mechanics tool set includes:

• Explicit structural dynamics FEM codes such as DYNA3D and LS-DYNA
• Mixed method Arbitrary Lagrangian Eulerian (ALE) codes
• Mesh generation tools such as ANSYS ICEM CFD
• Post-processing using various tools such as FIELDVIEW