scholarly journals Mathematical Optimization of Elastic Properties: Application to Cementless Hip Stem Design

1997 ◽  
Vol 119 (2) ◽  
pp. 166-174 ◽  
Author(s):  
J. H. Kuiper ◽  
R. Huiskes
Keyword(s):  
Bone Loss ◽  
Design Optimization ◽  
Elastic Properties ◽  
Stress Shielding ◽  
Proximal Part ◽  
Optimization Method ◽  
Arbitrary Distribution ◽  
Interface Failure ◽  
Stem Design ◽  
Finite Element Program

The designer of a cementless hip stem in total hip replacement must find a balance between two conflicting demands. On the one hand, a stiff stem shields the surrounding bone from mechanical loading (stress shielding), which may lead to bone loss, particularly around the proximal part of the stem. Reducing the stem stiffness decreases the amount of stress shielding and hence the amount of bone loss. However, this measure inevitably promotes higher proximal interface stresses and thereby increases the risk of proximal interface failure. The designer’s task therefore is to optimize the stem stiffness in order to find the best compromise in the conflict. Yet, a better compromise might be found when the stem material was nonhomogeneous, in other words when an arbitrary distribution of the elastic properties inside the stem was allowed. The number of conceivable designs would increase enormously, making the designer’s task almost impossible. In the present paper, we develop a numerical design optimization method to determine the optimal stiffness characteristics for a hip stem. A finite element program is coupled with a numerical optimization method, thus producing a design optimization scheme. The scheme minimizes the probability for interface failure while limiting the amount of bone loss, by adapting the parameters describing the nonhomogeneous elastic modulus distribution. As an example, a simplified model of a hip stem is made, whose modulus distribution is optimized. Assuming equal long-term bone loss, the maximum interface stress can be reduced by over 50 percent when compared to a homogeneous flexible stem, thus demonstrating the value of the new approach.

Design Optimization Method for Composite Components Based on Moment Reliability-Sensitivity Criteria

2017 ◽  
Vol 34 (3) ◽  
Author(s):  
Zhigang Sun ◽  
Changxi Wang ◽  
Xuming Niu ◽  
Yingdong Song
Keyword(s):  
Sensitivity Analysis ◽  
Design Optimization ◽  
Reliability Analysis ◽  
Efficient Method ◽  
Ceramic Matrix Composites ◽  
Optimization Method ◽  
Calculation Model ◽  
Arbitrary Distribution ◽  
Engineering Practice ◽  
Reliability Sensitivity

AbstractIn this paper, a Reliability-Sensitivity Based Design Optimization (RSBDO) methodology for the design of the ceramic matrix composites (CMCs) components has been proposed. A practical and efficient method for reliability analysis and sensitivity analysis of complex components with arbitrary distribution parameters are investigated by using the perturbation method, the respond surface method, the Edgeworth series and the sensitivity analysis approach. The RSBDO methodology is then established by incorporating sensitivity calculation model into RBDO methodology. Finally, the proposed RSBDO methodology is applied to the design of the CMCs components. By comparing with Monte Carlo simulation, the numerical results demonstrate that the proposed methodology provides an accurate, convergent and computationally efficient method for reliability-analysis based finite element modeling engineering practice.

Shape-design optimization of hull structures considering thermal deformation

2013 ◽  
Vol 228 (13) ◽  
pp. 2266-2277
Author(s):  
Myung-Jin Choi ◽  
Min-Geun Kim ◽  
Seonho Cho
Keyword(s):  
Optimal Design ◽  
Design Optimization ◽  
Thermal Deformation ◽  
Parametric Design ◽  
Optimization Method ◽  
Optimization Process ◽  
Design Parameters ◽  
Shape Design ◽  
Shape Design Optimization ◽  
Modified Method

We developed a shape-design optimization method for the thermo-elastoplasticity problems that are applicable to the welding or thermal deformation of hull structures. The point is to determine the shape-design parameters such that the deformed shape after welding fits very well to a desired design. The geometric parameters of curved surfaces are selected as the design parameters. The shell finite elements, forward finite difference sensitivity, modified method of feasible direction algorithm and a programming language ANSYS Parametric Design Language in the established code ANSYS are employed in the shape optimization. The objective function is the weighted summation of differences between the deformed and the target geometries. The proposed method is effective even though new design variables are added to the design space during the optimization process since the multiple steps of design optimization are used during the whole optimization process. To obtain the better optimal design, the weights are determined for the next design optimization, based on the previous optimal results. Numerical examples demonstrate that the localized severe deviations from the target design are effectively prevented in the optimal design.

scholarly journals A New Design Optimization Method for Permanent Magnet Synchronous Linear Motors

Energies ◽  
2016 ◽  
Vol 9 (12) ◽  
pp. 992 ◽  
Author(s):  
Juncai Song ◽  
Fei Dong ◽  
Jiwen Zhao ◽  
Siliang Lu ◽  
Le Li ◽  
...  
Keyword(s):  
Design Optimization ◽  
Permanent Magnet ◽  
Optimization Method ◽  
Linear Motors

scholarly journals FEM Based Preliminary Design Optimization in Case of Large Power Transformers

2019 ◽  
Author(s):  
Tamás Orosz ◽  
David Pánek ◽  
Pavel Karban
Keyword(s):  
Design Optimization ◽  
Design Process ◽  
Optimization Problems ◽  
Optimization Method ◽  
Power Transformers ◽  
Design Stage ◽  
Preliminary Design ◽  
Large Power ◽  
Custom Made ◽  
Transformer Design

Since large power transformers are custom-made, and their design process is a labor-intensive task, their design process is split into different parts. In tendering, the price calculation is based on the preliminary design of the transformer. Due to the complexity of this task, it belongs to the most general branch of discrete, non-linear mathematical optimization problems. Most of the published algorithms are using a copper filling factor based winding model to calculate the main dimensions of the transformer during this first, preliminary design step. Therefore, these cost optimization methods are not considering the detailed winding layout and the conductor dimensions. However, the knowledge of the exact conductor dimensions is essential to calculate the thermal behaviour of the windings and make a more accurate stray loss calculation. The paper presents a novel, evolutionary algorithm-based transformer optimization method which can determine the optimal conductor shape for the windings during this examined preliminary design stage. The accuracy of the presented FEM method was tested on an existing transformer design. Then the results of the proposed optimization method have been compared with a validated transformer design optimization algorithm.

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