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本文建立了混合离散变量多目标结构模糊优化设计的数学模型:提出了模糊寻优区间、模糊优越混合离散解集和模糊可行集的概念; 相似文献
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研究半导体制冷片几何参数的影响,往往设置固定的制冷片冷热端温度及输入电流。本文通过固定半导体制冷片外部的冷热端换热条件及输入电压,逐一分析了制冷片多个几何参数对制冷量、COP和制冷片冷端温度的影响,对每一个影响项的物理含义都给出了详细的说明,揭示了这些参量之间存在着的耦合关系。并在此基础上,综合制冷量、COP和制冷片冷端温度3个优化目标对制冷片几何参数选取范围的约束特性,提出了基于多目标优化的几何参数选择图,该图可快速清晰地得到不同需求下最佳的pn结几何参数。如在设置的边界条件下,当冷端温度需求为280 K,制冷量为15 W时,存在几何参数的最优解,而当冷端温度需求为240 K,制冷量为100 W时,则不存在可同时满足冷端温度和制冷量需求的几何参数。 相似文献
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本文通过适当变量代换,将钢桁结构几何优化模型表达为序列二次规划问题,并以最大熵的迭代格式表示之,最后以实例验证了该方法的可靠性。 相似文献
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目的 基于平板线圈对AA1060–DP600板材电磁脉冲连接过程进行数值模拟与工艺实验,探索线圈匝数、搭接区宽度、搭接间隙和放电电压等4个参数对连接接头质量的影响。方法 基于有限元分析软件(LS–DYNA),建立尺寸参数为80 mm×40 mm×1 mm的AA1060–DP600板材电磁脉冲连接有限元模型;基于平板线圈搭接实验装置进行工艺实验,采用电子万能实验机、金相显微镜对接头拉伸性能进行测试并观察其微观形貌,结合模拟与工艺实验的结果分析各个参数对接头质量的影响。结果 随平板跑道线圈匝数由1匝增至6匝,飞板与基板碰撞速度先升后降,在3匝时达到最大值;搭接间隙过大(2.5 mm)或过小(1.5 mm)都会使碰撞速度下降,进而使接头强度下降;碰撞速度和接头强度与搭接区宽度和放电电压成正相关,放电电压在9 kV及以上时更易实现连接;连接接头界面总体趋于平直,部分区域出现小波峰大波长的波形。结论 以拉伸性能最优为标准,最优的工艺参数为线圈匝数3匝、搭接间隙2 mm、搭接区宽度25 mm、放电电压11 kV,此条件下试件可承受的最大载荷为2.33 kN,达到母材AA1060的75%。 相似文献
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目的 针对目前车用高强钢和高强度铝合金板料在无铆连接工艺上出现的成形接头效果不佳及接头强度难以满足实际工况等问题,提出一种钢/铝异种材料热无铆塑性连接工艺,以有效提高22MnB5高强钢与7050铝合金铆接接头性能。方法 通过软件Abaqus建立钢/铝异种材料无铆塑性连接有限元模型,对塑性连接接头尺寸特性进行分析;进一步通过仿真分析研究高强钢初始铆接温度对接头截面颈厚与自锁值的影响,并采用拉伸试验研究铝板在不同初始温度下及成形接头在不同冷却方式下对无铆塑性连接接头性能的影响。结果 将有限元仿真分析结果与试验的金相图进行了对比研究,得出二者成形接头的尺寸基本吻合,并产生了有效的机械自锁,证明了仿真模型的准确性。随后,经仿真分析确定,钢加热至700℃时,接头颈厚值与自锁值均最大,分别为0.402、0.357 mm,该成形温度下接头特征尺寸最佳。最后,通过试验分析发现,常温铆接、阀冷、室冷、水冷的拉力峰值分别为2.076 3、5.314 0、2.411 1、2.024 0 kN。由此可得,热处理后接头的抗剪切强度较常温铆接提高了28.5%,在3种冷却方式处理下,阀冷的接头强度最佳,水冷的接头强... 相似文献
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The purpose of this study is to propose the design method of mechanical clinching tools, which is used to join aluminium alloy sheets in automobiles. Based on the analytical model used to predict the strength of the mechanical clinched joint, the design method of clinching tools that can satisfy the required joint strength is proposed. The analytical model has been defined as a function of the neck-thickness and the undercut, which are the presented mechanical clinched joint geometry. And joint geometry is defined by the shape parameters of the clinching tools. To obtain the desired joint strength, the required neck-thickness and undercut are inversely calculated from the analytical model. The mechanical clinching tools that join Al6063 alloy sheets are designed by the proposed method. FE-analysis and mechanical clinching test were performed for optimal conditions obtained from the proposed design method. The result of the FE-analysis and that of the mechanical clinching test showed good agreement of the clinched joint geometry. The H-type tensile test for mechanical clinched joint was carried out to evaluate the strength of the mechanical clinched joint designed by the proposed design method. The result of the tensile test showed that the fracture load satisfied the required joint strength. Also, the top-hat impact test was performed to evaluate the feasibility of using mechanical clinching for automotive component assembly. The result of impact test showed that mechanical clinching was able to produce similar crash resistance as self-piercing riveting. 相似文献
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This article introduces a new method entitled multi-objective feasibility enhanced partical swarm optimization (MOFEPSO), to handle highly-constrained multi-objective optimization problems. MOFEPSO, which is based on the particle swarm optimization technique, employs repositories of non-dominated and feasible positions (or solutions) to guide feasible particle flight. Unlike its counterparts, MOFEPSO does not require any feasible solutions in the initialized swarm. Additionally, objective functions are not assessed for infeasible particles. Such particles can only fly along sensitive directions, and particles are not allowed to move to a position where any previously satisfied constraints become violated. These unique features help MOFEPSO gradually increase the overall feasibility of the swarm and to finally attain the optimal solution. In this study, multi-objective versions of a classical gear-train optimization problem are also described. For the given problems, the article comparatively evaluates the performance of MOFEPSO against several popular optimization algorithms found in the literature. 相似文献
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为实现加工中心动静态性能不低于优化前性能,达到整机重量最轻的要求,本文提出了一种复合优化方法来研究多变量、多约束和多目标的数控加工中心优化设计。采用有限元分析和实验模态测试方法分析各大件动态性能,并验证了有限元模型的精确性。然后以该有限元模型为基础进行静态分析,得出各大件的最大变形及应力等。以柔度为目标,采用变密度法拓扑优化设计立柱结构的外形框架;以固有频率为目标,基于元结构的可适应性动态优化方法设计加工中心的筋板结构;以固有频率和质量为目标,基于响应面法的尺寸优化确定各结构的最优尺寸。最后将优化后的各大件进行整机装配,分析校核整机动静态性能。分析结果表明,优化后的整机在保证加工中心动静态性能的条件下,整机质量从12749kg减少到12127kg,减重达到4.9%,达到了整机的优化设计要求,说明该方法具有较高的精度和较强的工程实用性。 相似文献
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6016与H70板的冲压变形连接过程及剥离强度分析 总被引:1,自引:0,他引:1
对6016与H70板的冲压变形连接和剥离过程进行了物理实验和连续数值模拟,分析了不同模具与工艺参数对连接点颈部厚度、互锁及金属流动的影响.研究表明:随着凸模圆角半径(Rp)增大,颈厚值(Tn)增大,互锁值(Tu)减小;凹模深度(Hd)增大,Tn减小、Tu增加.底部厚度X取决于凸模下压量,过大底部材料流动不到位影响互锁,过小则底部太薄,推荐X取总板厚的25%.采用L型试样测剥离抗拉强度时应考虑加载力臂的影响.利用数值模拟可以预测连接强度,并为工艺与模具设计提供有效指导. 相似文献
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Kiran K. Annamdas 《工程优选》2013,45(8):737-752
This study proposes particle swarm optimization (PSO) based algorithms to solve multi-objective engineering optimization problems involving continuous, discrete and/or mixed design variables. The original PSO algorithm is modified to include dynamic maximum velocity function and bounce method to enhance the computational efficiency and solution accuracy. The algorithm uses a closest discrete approach (CDA) to solve optimization problems with discrete design variables. A modified game theory (MGT) approach, coupled with the modified PSO, is used to solve multi-objective optimization problems. A dynamic penalty function is used to handle constraints in the optimization problem. The methodologies proposed are illustrated by several engineering applications and the results obtained are compared with those reported in the literature. 相似文献
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This article presents a formal optimization study of the design of small livestock trailers, within which the majority of animals are transported to market in the UK. The benefits of employing a headboard fairing to reduce aerodynamic drag without compromising the ventilation of the animals’ microclimate are investigated using a multi-stage process involving computational fluid dynamics (CFD), optimal Latin hypercube (OLH) design of experiments (DoE) and moving least squares (MLS) metamodels. Fairings are parameterized in terms of three design variables and CFD solutions are obtained at 50 permutations of design variables. Both global and local search methods are employed to locate the global minimum from metamodels of the objective functions and a Pareto front is generated. The importance of carefully selecting an objective function is demonstrated and optimal fairing designs, offering drag reductions in excess of 5% without compromising animal ventilation, are presented. 相似文献