ESLDYNA is a plug-in tool that couples Genesis to LS-DYNA Nonlinear Structural Analyses. It is based on the Equivalent Static Loads (ESL) method to perform optimization based on a nonlinear finite element analysis with Genesis as the structural optimization program. ESLDYNA takes advantage of the capability of Genesis, a linear structural optimization program, to solve large scale optimization problems based on the responses from a nonlinear finite element analysis. It also helps to significantly reduce the design time by identifying high performance designs with five to ten nonlinear analyses.
Most of different types of design optimization techniques in Genesis are available to the user for designing the nonlinear model. Multiple loading conditions in the nonlinear analysis, using several LS-DYNA input decks, can be analyzed simultaneously to achieve optimal solutions. The available plug-in to Design Studio, provides an easy to use interface with seamless integration between Genesis and LS-DYNA.
ESLDYNA is an implementation of the ESL method for coupling a nonlinear analysis with a linear optimization software for designing the nonlinear model. ESLs are defined as a set of static loads that produces the same response field as obtained in the nonlinear analysis. These loads are used to perform the optimization on the linear model. Optimization results are updated in the nonlinear analysis and a new response field is generated. This process is repeated until design convergence. In case of a transient nonlinear analysis, the time domain is discretized and applied as multiple loadcases on the linear model. During optimization, ESL is no longer equivalent if model (size, shape or topology) is changed. LS-DYNA can not produce the same responses with an updated model from GENESIS optimization. Thus it is required to re-calculate the nonlinear responses using the updated FE model.
Multiple loading conditions from the nonlinear analysis can be simultaneously considered for the optimization. Each loading condition would be applied as separate loadcases on the linear structural model. ESLDYNA facilitates simultaneously running multiple LS-DYNA analyses to reduce overall design time. Most of the optimization features that are available in GENESIS can be used in ESLDYNA.
I:Topometry Optimization for Frontal Impact Rail Design to Minimize Firewall Intrusion
Using coarse Taurus FE input deck, demo case is shown to perform topometry optimization of frontal rail design to minimize firewall intrusion. Totally 5200 design variables are considered for mixed sizing and topometry optimization. Shell thickness can vary from 0.5 to 2 times of original thickness. ESL defines the firewall intrusion at 75 ms only. The optimization converges within 10 LS-DYNA runs and 50 Genesis iterations. Topometry optimization gets element by element thickness distribution which can give perspective for structural realization to improve crashworthiness.