Structural Optimization for Non-Linear Behavior Using Equivalent Static Loads by Proportional Transformation of Loads

2006 ◽  
Vol 30 (1) ◽  
pp. 66-75
Author(s):  
Ki-Jong Park ◽  
Yong-Deok Kwon ◽  
Kee-Nam Song ◽  
Gyung-Jin Park
Keyword(s):  
Structural Optimization ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Linear Behavior ◽  
Non Linear

Non-linear dynamic response structural optimization for frontal-impact and side-impact crash tests

2016 ◽  
Vol 231 (5) ◽  
pp. 600-614 ◽  
Author(s):  
Youngmyung Lee ◽  
Gyung-Jin Park
Keyword(s):  
Dynamic Response ◽  
Boundary Conditions ◽  
Structural Optimization ◽  
Side Impact ◽  
Static Response ◽  
Static Loads ◽  
Linear Dynamic ◽  
Equivalent Static Loads ◽  
Non Linear ◽  
Equivalent Static Loads Method

Vehicle crash optimization is a representative non-linear dynamic response structural optimization that utilizes highly non-linear vehicle crash analysis in the time domain. In the automobile industries, crash optimization is employed to enhance the crashworthiness characteristics. The equivalent-static-loads method has been developed for such non-linear dynamic response structural optimization. The equivalent static loads are the static loads that generate the same displacement field in linear static analysis as those of non-linear dynamic analysis at a certain time step, and the equivalent static loads are imposed as external loads in linear static structural optimization. In this research, the conventional equivalent-static-loads method is expanded to the crash management system with regard to the frontal-impact test and a full-scale vehicle for a side-impact crash test. Crash analysis frequently considers unsupported systems which do not have boundary conditions and where adjacent structures do not penetrate owing to contact. Since the equivalent-static-loads method uses linear static response structural optimization, boundary conditions are required, and the impenetrability condition cannot be directly considered. To overcome the difficulties, a problem without boundary conditions is solved by using the inertia relief method. Thus, relative displacements with respect to a certain reference point are used in linear static response optimization. The impenetrability condition in non-linear analysis is transformed to the impenetrability constraints in linear static response optimization.

Structural optimization of an automobile roof structure using equivalent static loads

2008 ◽  
Vol 222 (11) ◽  
pp. 1985-1995 ◽  
Author(s):  
S-B Jeong ◽  
S-I Yi ◽  
C-D Kan ◽  
V Nagabhushana ◽  
G-J Park
Keyword(s):  
Structural Optimization ◽  
Linear Response ◽  
Safety Regulation ◽  
National Highway Traffic Safety ◽  
Static Loads ◽  
Linear Dynamic ◽  
Equivalent Static Loads ◽  
Roof Structure ◽  
Non Linear ◽  
Response Optimization

In a vehicle rollover accident, the strength of the roof structure is an important factor of security in order to reduce the death and injury rates. The National Highway Traffic Safety Administration proposed strength requirements of the roof structure on roof crush resistance in the Federal Motor Vehicle Safety Standard (FMVSS) 216. Recently, there have been many structural optimization studies that design the structure of a vehicle to satisfy this safety regulation. Most previous studies used approximation methods such as the response surface method (RSM) as a crash problem has high non-linearity and difficulty in sensitivity calculation. However, the solution from the RSM may not be accurate and has a limit on the number of design variables. In this research, non-linear dynamic (transient) response optimization using equivalent static loads (ESLs) is proposed to design the structure of a vehicle to satisfy the safety regulation. ESLs for linear response analysis are made to generate the same displacement field as that from non-linear dynamic loads at each time step of non-linear dynamic analysis. A dynamic load is transformed to a set of ESLs. The static loads are used as the multiple loading conditions for linear response optimization, which are not costly in the linear response optimization process. Size optimization using ESLs is performed to reduce the structural mass while the FMVSS 216 regulation is satisfied. The optimum results using ESLs are compared with those from the RSM. As a result, the proposed method is very efficient and derives good solutions. Non-linear analysis is performed using the commercial code LS-DYNA. NASTRAN is used in calculating the ESL and linear response optimization. LS-OPT is utilized for structural optimization using the RSM.

Structural Optimization of a Joined-Wing Using Equivalent Static Loads

2006 ◽  
Vol 30 (5) ◽  
pp. 585-594
Author(s):  
Hyun-Ah Lee ◽  
Yong-Il Kim ◽  
Gyung-Jin Park ◽  
Byung-Soo Kang
Keyword(s):  
Structural Optimization ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Joined Wing
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