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随着航天事业的发展,桁架作为航天器主承力结构应用越来越广泛,并呈现大型化复杂化的发展趋势。传统模式下航天器桁架结构设计效率低下,无法适应“快速响应约束,迭代更新高效”等应用要求,制约桁架结构的发展。针对这一现象,文中基于自顶向下(Top-Down)设计模式和参照柔性相关思想,提出了航天器桁架结构快速设计方法,并进行了验证。结果表明,航天器桁架结构快速设计方法逻辑关系明确,简便实用,能够实现结构元件自动创建和装配,快速响应外部约束并自适应更新,能确保设计状态的迭代有效可控,显著提升桁架结构设计效率,可推广应用于航天器桁架结构设计。 相似文献
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基频约束结构优化设计的线性矩阵不等式方法 总被引:1,自引:1,他引:0
介绍了半定规划及线性矩阵不等式 (LMI)的基本概念 ,给出具有基频约束的桁架结构优化问题的半定规划形式。半定规划法 (或称线性矩阵不等式方法 )可以有效地求解该问题的全局最优解 ,最后以一个简单桁架结构为算例 相似文献
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The minimum weight structural configuration of pin-jointed truss cantilevers of given external shape
R.H. Mole 《International Journal of Mechanical Sciences》1973,15(1):49-63
The minimum weight configuration of a statically determinate cantilever truss of known external shape is formulated as a non-linear mathematical programming problem which can be solved using Dynamic Programming. The recursive equations lead to a closed-form solution for equal permissible stresses in tension and compression, and weight comparisons with the thin webbed beam, the Warren truss, and the equivalent Michell structure are presented.When the design criteria are tensile yield or buckling under compressive load, numerical tabulations are required in the solution. But it is demonstrated, by way of an example, that many aspects of practical problems can be accommodated with relative ease using this approach. 相似文献
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在确保自动扶梯桁架的结构强度和安全性能前提下,为了提高系列化自动扶梯桁架设计开发效率,运用有限元二次开发和Visual C++以及数据接口技术,根据不同的设计、制造和检验要求,研究了不同参数情况下自动扶梯桁架的结构设计特点和强度特性,分析了边界载荷最大化桁架强度特点。研究结果表明,运用自动扶梯参数化有限元分析平台,用户只需输入参数,通过自动建模就可计算得到系列化桁架的结构强度结果,大大简化了分析过程,提高了分析效率。 相似文献
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The mathematical model of optimal placement of active members in truss adaptive structures is essentially a nonlinear multi-objective optimization problem with mixed variables,it is usually much difficult and costly to be solved.In this paper,the optimal location of active members is treated in terms of(0,1)discrete variables.Structural member sizes,control gains,and(0,1)placement variables are treated simultaneously as design variables.Then,a succinct and reasonable compromise scalar model,which is transformed from original multi-objective optimization,is established,in which the(0,1)discrete variables are converted into an equality constraint.Secondly,by penalty function approach,the subsequent scalar mixed variable compromise model can be formulated equivalently as a sequence of continuous variable problems.Thirdly,for each continuous problem in the sequence,by choosing intermediate design variables and temporary critical constraints,the approximation concept is carried out to generate a sequence of explicit approximate problems which enhance the quality of the approximate design problems.Considering the proposed method,a FORTRAN program OPAMTAS2.0 for optimal placement of active members in truss adaptive structures is developed,which is used by the constrained variable metric method with the watchdog technique(CVMW method).Finally,a typical 18 bar truss adaptive structure as test numerical examples is presented to illustrate that the design methodology set forth is simple,feasible,efficient and stable.The established scalar mixed variable compromise model that can avoid the ill-conditioned possibility caused by the different orders of magnitude of various objective functions in optimization process,therefore,it enables the optimization algorithm to have a good stability.On the other hand,the proposed novel optimization technique can make both discrete and continuous variables be optimized simultaneously. 相似文献
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同轴轻型空间遥感器支撑桁架的设计与试验 总被引:4,自引:3,他引:1
为满足空间遥感器的高度轻量化要求,提高其结构的基频,减少100 Hz以下低频振动的影响,研究了高比刚度的轻型支撑桁架结构。针对同轴长焦距光学系统,基于三角形稳定的原理设计了一种6杆碳纤维复合材料桁架结构,并基于有限元法完成了其优化设计,使其质量降低了11%。为验证其可行性,研制了力学模拟件,进行了工程分析和动力学试验,并讨论了分析和试验的误差来源。分析和试验显示,模拟件的固有频率超过了120 Hz,表明所设计的支撑桁架合理可行,能够满足长焦距空间遥感器的使用要求。该结构在质量为13 kg的前提下,解决了目前该型遥感器基频较低的难题,该设计已成功应用于某相机结构中。 相似文献
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针对桁架内移动的避障要求,研究双臂手移动机器人桁架内运动的规划方法。基于状态空间模型提出直角坐标空间下的六面心、八边心和八顶点搜索算法,避免了C空间内复杂度呈几何级数增长的问题,实现了末端无碰撞路径搜索。建立双臂手移动机器人三节臂的平面内避障准则,解决了机器人在桁架内运动时机器人臂与桁架杆的碰撞问题。根据平面内避障准则和臂形标志,求得了各个关节角的解析解,解决了数值解的不封闭问题。每个时刻末端姿态由通用旋转变换公式线性插值得到,在Matlab中仿真双臂手移动机器人桁架内的运动,验证了双臂手移动机器人在桁架内运动时避障方法的可行性。 相似文献
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应用模块化和产品平台的思想是企业设计和开发产品族(系列)的重要策略。本文提出一种可用于产品族设计的二级优化方法。该优化方法将产品族设计优化分为二个层次:产品平台优化层次和专用模块的优化层次。为了提高这种优化方法的可靠性和减少计算量,在二级优化基本框架基础上引入了代理模型技术。将二级优化方法应用于桁架族优化设计算例,计算结果表明:基于代理模型的二级优化方法能成功地解决桁架族优化设计问题,具有很好的可靠性,而且能有效地减少产品族优化设计中计算量。 相似文献
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This paper presents a transformation method by which a static balancer of a truss is transformed into static balancers of various mechanisms. For conventional design methods the kinematics and potential energy of every mechanism should be computed to design a static balancer. For the proposed design method, however, no computation of kinematics and potential energy is necessary to obtain static balancers of various mechanisms, once a static balancer of a truss has been designed. The concepts of the Baranov truss and associated linkage are adopted to determine transformation relations. Conversion rules are developed in the viewpoint of gravitational torques and deletion rules are determined to apply conversion rules to the design equation. Static balancers of various mechanisms (four-bar linkage, slider crank mechanism, Watt mechanism and sliding mechanism derived from the watt mechanism) are derived from those of the five-link and seven-link Baranov trusses in this paper. Simulations results showed that complete gravity compensation is achieved for all derived mechanisms from Baranov trusses. 相似文献
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一种9杆巴氏衍架的装配形态研究 总被引:1,自引:1,他引:1
选定其中的一个 5元构件为固定构件 ,对一种 9杆巴氏衍架装配形态进行了分析。如果将该固定构件去掉 ,这一问题等同于一个平面 8杆 12副阿苏尔杆组的位置分析。采用复数矢量法 ,先列出用于装配形态分析的含 4个角位移变量的 4个独立矢量方程 ,然后将它们转化为复数形式的代数方程组 ,直接采用结式消元方法对上述方程组进行消元 ,得到了一个单变量的 5 4次代数方程 ,表明该种 9杆巴氏衍架可能存在 5 4种装配形态。对该代数方程直接进行求解 ,然后利用辗转相除法求出其它 3个未知变量的值 ,最后利用复数的三角变换 ,求出了 5 4组对应于该巴氏衍架装配形态的 4个角位移值 ,从而完成了它的装配形态分析 相似文献