Analysis and optimization of weakly coupled thermoelastoplastic systems with applications to weldment design

SUMMARYA polymer processing design methodology is presented which can be used to improve the production of plastic components manufactured via extrusion and injection molding processes. The design method combines polymer process modelling, design sensitivity analysis and numerical optimization. It is applicable to systems with creeping ow of purely viscous non-Newtonian uids through thin cavities where the lubrication approximation may be applied. An analysis and an adjoint design sensitivity analysis are presented for the steady-state coupled system which describes the pressure and residence time distributions in sheeting dies. The resulting methodology is then used to deÿne the optimal die cavity shape and relevant process parameters in a sheeting die design example. A second example considers tooling and process design for the polymer injection molding process. A coupled transient mold ÿlling analysis and design sensitivity analysis based on the direct di erentiation method are developed where attention is given to describing the location of the gates in the mold cavity. The latter is illustrated through the process design of a plastic automotive component.

Section: Introductionmentioning

confidence: 99%

Design sensitivity analysis and optimization for polymer sheet extrusion and mold filling processes

Smith

2003

“…For coupled ÿeld problems, the SA based on complex nonlinear models describing the response of a multidisciplinary system of interest remains a challenging task. In thermoelasticity adjoint SA formulations have been introduced by Meric [7,8] for steady-state problems and in thermoelastoplasticity by Michaleris et al [9,10] for static and transient problems. The adjoint SA approach has been applied to magnetohydrodynamic channel ows by Meric [11].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis and design optimization of three‐dimensional non‐linear aeroelastic systems by the adjoint method

Maute

Nikbay

Farhat

2002

124

SUMMARYWe consider the problem of optimizing a non-linear aeroelastic system in steady-state conditions, where the structure is represented by a detailed ÿnite element model, and the aerodynamic loads are predicted by the discretization of the non-linear Euler equations. We present a solution method for this problem that is based on the three-ÿeld formulation of uid-structure interaction problems, and the adjoint approach for coupled sensitivity analysis. We discuss the computational complexity of the proposed solution method, describe its implementation on parallel processors, and illustrate its computational e ciency with the aeroelastic optimization of various wings.

“…The methodology for evaluating design sensitivities in coupled problems involves performing the sensitivity analysis for the thermal problem initially, and importing the results for the elasto-plastic sensitivity analysis. Sensitivity analysis has been implemented in minimizing the weight of welded structures [36] and minimizing welding residual stress and distortion [37].…”

Section: Introductionmentioning

confidence: 99%

Optimization of thermo‐elasto‐plastic processes using Eulerian sensitivity analysis

Paul

Michaleris

Shanghvi

2003

E. Adams Dr.; Columbus; OH 43221; U.S.A. SUMMARYA computational scheme for the analysis and optimization of quasi-static thermo-mechanical processes is presented in this paper. In order to obtain desirable mechanical transformations in a workpiece using a thermal treatment process, the optimal control parameters need to be determined. The problem is addressed by posing the process as a decoupled thermo-mechanical ÿnite element problem and performing an optimization using gradient methods. The forward problem is solved using the Eulerian formulation since it is computationally more e cient compared to an equivalent Lagrangian formulation. The design sensitivities required for the optimization are developed analytically using direct di erentiation. This systematic design approach is applied to optimize a laser forming process. The objective is to maximize the angular distortion of a specimen subject to the constraint that the phase transition temperature is not exceeded at any point in the model.