Thermal-Mechanical interaction ranges from simple thermal stress (one-way coupling in which an uncoupled heat transfer simulation drives a stress analysis through thermal expansion) to more complex friction-driven heat transfer (in which frictional sliding generates heat as in brake systems) to fully coupled temperature-displacement simulation (in which motion affects heat transfer and heat transfer affects motion). Examples include thermo-mechanical durability in many industries from internal combustion engines in Automotive to package reliability in Electronics. Also, many manufacturing processes such as soldering (cooling from a liquid to solid state), forging, and extrusion involve Thermal-Mechanical Multiphysics.
The Abaqus Unified FEA products have included extensive capabilities for thermal-mechanical Multiphysics simulation from the very first version of Abaqus in the 1980's—all within the comfortable environment of Abaqus. These capabilities include thermal stress, adiabatic response, and coupled thermo-mechanical simulation in both Abaqus/Standard and Abaqus/Explicit.
Hot forming processes introduce very large plastic strains in the bulk material. The work due to the plastic straining is dissipated as heat, thus raising the temperature of the bulk material. This is an important consideration for the design of manufacturing processes, since a significant temperature rise in the bulk material can degrade its properties.
The Mutiphysics solution from SIMULIA offers a fully-coupled thermal-mechanical solution to address this need. Heat generated through plastic dissipation couples the thermal response to the mechanical one, while temperature-dependent mechanical properties and thermal expansion provide the coupling in the reverse direction.
With the benefit of accurate numerical simulations, both the cost and time associated with the product development cycle can be reduced substantially. Advanced FE simulation allows the engineer to identify and correct potential forming problems prior to tooling fabrication, cuts time and costs associated with tooling rework, and reduces overall effort needed for prototyping. The blank is made of a steel alloy. The forming tools are assumed rigid. Two simulations are considered: one assumes adiabatic conditions (i.e., assumes the process happens so quickly that there is no time for the heat to diffuse); the other is a fully-coupled thermal-mechanical solution including the effects of heat transfer between the bulk material and the tools.
The figure shows the temperature distribution in the bulk material assuming adiabatic conditions (left) and fully-coupled response (right). The temperature scale is the same in both images. It is clear the adiabatic analysis predicts much greater heating in the material in this case. Thus, the fully-coupled solution is needed to accurately predict the combined thermal and mechanical responses.