<p>Structural optimal design is traditionally performed according to the elastic limit rule, which makes the structure over-weighted or strength over conservative to an extent. Shakedown theory is implemented in the present study in order to measure the load-capacity performance of the structure. It can determine the strength of a structure under arbitrary varying loads without loading history where failure forms of incremental collapse, ratcheting and alternate plasticity will be avoided. Moreover, the full potential of a material can be utilized by following the shakedown limit framework. Therefore, under this framework, by sacrificing&nbsp;some abundant loading bearing capacity, an extremely lightweight design of the structure can be reached. The current research presents a mathematical and algorithmic framework for producing extreme lightweight designs of structures exhibit constrained shakedown loading capacity, which is an innovative means to the lightweight design and makes the optimal structure design in a relatively practical way. Constrained shakedown loading capacity is determined by analyzing the original design of the structure. With this motivation, the formula of the proposed shakedown limited parameter optimization problem is derived and solved based on a genetic-gradient coupling algorithm. The present coupling algorithm is essentially solving a double-loop problem where the inner loop adopts the interior point method to solve the shakedown problem under a given parameter combination while the outer loop uses a genetic algorithm to find the optimal parameters based on a given shakedown loading factor. In addition, an external database technique is applied to accelerate computation and prevent unexpected interruptions. Results show that this technique can lead to a significant reduction of computation time in the engineering calculation demands. The accuracy and effectiveness of the proposed numerical optimization method are validated and demonstrated by a classical problem and subsequently adopted in optimal parameter design of the connecting structure to be used in a manned airtight module. In the end, the research suggests an optimal result for both load capacity and lightweight design for the manned airtight module. And an extreme lightweight design is given by sacrificing&nbsp;redundant load capacity. This study confirmed that the genetic-gradient coupling algorithm is an effective means for determining the optimal parameter in accordance with the shakedown load domain. In addition, the results of this study support the idea that shakedown analysis should be used in the optimization design of airtight modules instead of using the traditional elastic limit rule. As the load capacity evaluates by shakedown analysis would be more factual. Moreover, the redundant shakedown load capacity part can be adopted in an extremely lightweight design. Whilst this study only tests two design parameters and one object with respect to one nonlinear condition in the optimization, further research might investigate the potential ability of the coupling algorithm for multi-parameter and multi-object optimization.</p>

Ultimate Lightweight Design Based on Shakedown Strength and Its Application on Designing a Manned Airtight Module

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.