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Modified genetic algorithm for optimal design of truss structures 桁架结构优化设计的改进遗传算法
Pub Date : 2024-04-04 DOI: 10.5755/j02.mech.36227
D. Šešok, R. Belevičius
In this paper, topology and shape optimization of truss or frame structures is discussed. The optimization starts from a structure, into which a finite number of nodesare set; all the nodes are connected together by trusses in all possible variants. Unfit variants of the truss system are rejected. Two alternative ways of the optimization are compared: topology optimization starting from initial structure with a larger number of nodes, and topology optimization starting from initial structure with smaller number of nodes but with additional shape optimization of the obtained topology. The topology optimization is solved with original modified genetic algorithm, giving better results in comparison with classical genetic algorithm. Instead of further development of constraint system, the additional step is introduced into algorithm – purification of genotype, which allows complementary improvement of particular population individuals, and together for the optimization process retains more possibilities than stiffening of constraints. The shape optimization is solved by classical genetic algorithm. Both strategies effectively improve the solution, however the common topology/shape optimization requires less computer resources. All numerical examples are obtained with original software developed by the authors.
本文讨论了桁架或框架结构的拓扑和形状优化。优化从一个结构开始,其中设置了有限数量的节点;所有节点通过桁架以各种可能的形式连接在一起。不合适的桁架系统将被剔除。比较了两种可供选择的优化方法:从节点数较多的初始结构开始进行拓扑优化,以及从节点数较少的初始结构开始进行拓扑优化,但对获得的拓扑结构进行额外的形状优化。拓扑优化采用原始改进遗传算法求解,与经典遗传算法相比结果更好。该算法没有进一步发展约束系统,而是引入了额外的步骤--纯化基因型,这使得特定群体个体得到了补充性改进,同时在优化过程中保留了比强化约束更多的可能性。形状优化由经典遗传算法解决。这两种策略都能有效地改进解法,但共同的拓扑/形状优化所需的计算机资源较少。所有数值示例都是通过作者开发的原创软件获得的。
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引用次数: 5
Lightweight Finite Element Analysis and Experimental Study of 90# Fifth Wheel 90# Fifth Wheel 的轻质有限元分析和实验研究
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.32962
Yanke Wen, H. Ji, Zhongman Cai, Guolong Cui, Haoqian Zhang
The fifth wheel is a connecting device between the semi-trailer and the tractor, which plays the role of connecting and steering. According to the finite element analysis technology, the fifth wheel model is established by CREO software, and import the established model into HyperWorks software, the static analysis and lightweight design of the structure are carried out by finite element simulation. Finally, the optimal solution of fifth wheel structure is obtained, The static performance of the optimized fifth wheel is verified, which proves that the optimized structure is reasonable and meets the requirements of strength and stiffness. After the optimization of fifth wheel for actual production test, the optimized fifth wheel to meet the requirements of national standards.
五轮是半挂车与牵引车之间的连接装置,起到连接和转向的作用。根据有限元分析技术,利用 CREO 软件建立五轮模型,并将建立的模型导入 HyperWorks 软件,通过有限元仿真进行结构的静力分析和轻量化设计。最后得到五轮结构的最优解,并对优化后的五轮进行静力性能验证,证明优化后的结构合理,满足强度和刚度的要求。优化后的五轮进行了实际生产试验,优化后的五轮满足国家标准要求。
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引用次数: 0
Portable Referee System for Volleyball Game Based on Pressure Monitoring and Self-Powering Communication 基于压力监测和自供电通信的排球比赛便携式裁判系统
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.33756
Jun Wu, Zile Fan
Sports refereeing has traditionally relied on human judgement, which can be prone to errors. However, the development of automatic referee systems has the potential to address this issue, improve training, and promote sports in the future. In this study, we present a novel and portable referee system specifically designed for volleyball games, which utilizes piezoelectric sensors to detect pressure and simultaneously harvest energy for powering the system. The system consists of two parts: a wearable glove and a device mounted on the volleyball. The glove part has five sensors fixed on the fingertips and the volleyball has eight sensors evenly distributed on its surface. The collected contact data from the sensors is wirelessly transmitted to a personal computer. Our experimental results demonstrate that the system can accurately capture a three-second contact and detect foul actions in a volleyball game. These findings highlight the potential of the system for sports and other monitoring applications.
体育裁判工作历来依赖于人的判断,而人的判断很容易出错。然而,自动裁判系统的开发有可能解决这一问题,改善训练,促进未来体育运动的发展。在本研究中,我们介绍了一种专为排球比赛设计的新型便携式裁判系统,该系统利用压电传感器检测压力,同时采集能量为系统供电。该系统由两部分组成:可穿戴手套和安装在排球上的装置。手套部分的指尖固定有五个传感器,排球表面均匀分布有八个传感器。传感器收集到的接触数据通过无线方式传输到个人电脑。实验结果表明,该系统能准确捕捉排球比赛中三秒钟的接触并检测出犯规动作。这些发现凸显了该系统在体育和其他监测应用方面的潜力。
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引用次数: 0
Dynamic Performance Optimization of Monorail Rapid Transit Formation Vehicles Based on Improved Artificial Potential Field Algorithm 基于改进的人工势场算法的单轨捷运编组车辆动态性能优化
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.34670
Haoxin Wu, Zixue Du, Zhen YANG, Xiaoxia WEN
This paper presents a new type of monorail rapid transit vehicle, which can operate in formation. In order to optimize the dynamic performance of the formation vehic-les when passing through the small radius curve, this paper first analyzes the structure of the new monorail rapid transit vehicle, and establishes the vehicle dynamic model and multi-body dynamics simulation model. Then the improved artificial potential field algorithm is used to build the formation vehicle operation controller. Finally, the dynamic performance evaluation index of the new mono-rail rapid transit formation vehicle is formulated, and the formation vehicle passing through the small radius curve scene is simulated. The simulation results show that the controller of the formation vehicle with dynamic optimi-zation control can effectively optimize the load transfer coefficient of running wheels, unbalanced centrifugal acce-leration and roll angle of vehicle body when passing thro-ugh the curve. Through this control method, the dynamic performance of formation vehicles passing through small radius curve lines can be optimized.
本文介绍了一种可编队运行的新型单轨快速交通车辆。为了优化编队车辆通过小半径曲线时的动态性能,本文首先分析了新型单轨快速交通车辆的结构,建立了车辆动力学模型和多体动力学仿真模型。然后采用改进的人工势场算法建立编组车辆运行控制器。最后,制定了新型单轨快速交通编组车辆的动态性能评价指标,并对编组车辆通过小半径曲线场景进行了仿真。仿真结果表明,采用动态优化控制的编组车辆控制器能有效优化通过弯道时运行车轮的载荷传递系数、不平衡离心加速度和车体侧倾角。通过这种控制方法,可以优化编队车辆通过小半径曲线线路时的动态性能。
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引用次数: 0
The Characterization of the Plastic Instability of S235 Thin Steel Sheets by Multiple Regression and Analysis of Variance Methods 用多元回归和方差分析方法表征 S235 薄钢板的塑性不稳定性
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.34036
N. Ghazouani, M. Nasri, Aboulbaba Eladeb, Wael Salah, M. Tashkandi, Nidhal Becheikh
In this study, we present a new identification method of parameters characterizing the elastoplastic damage behavior of sheet metal based on analysis of variance. The analysis covered experimental and numerical simulation results using the finite element method of the sheet mild steel bulge test. The identification procedure was validated through a confrontation between numerical simulations and experimental results on several hydroforming applications, such as a free expansion and an expansion in matrix cavities. Results show consistency between experimental observations and numerical predictions of instabilities. Furthermore, the location of risk areas of instability and rupture and the damage level could be quantified. The analysis focused on a set of results combining experimental data and numerical simulations of the bulge test of steel sheets. The identified models were validated thanks to a comparison between numerical simulations and experimental results of a set of forming applications by bulge test. The results show coherence between the experimental observations and the numerical predictions of the instabilities.
在本研究中,我们提出了一种基于方差分析的表征金属板弹塑性损伤行为参数的新识别方法。分析涵盖了使用有限元法进行的低碳钢板隆起试验的实验和数值模拟结果。通过对数值模拟和几种液压成形应用(如自由膨胀和基体空腔膨胀)的实验结果进行对比,验证了识别程序。结果表明,实验观察结果与不稳定性的数值预测结果是一致的。此外,还可以量化不稳定和破裂风险区域的位置以及损坏程度。分析的重点是结合钢板隆起试验的实验数据和数值模拟结果。通过对数值模拟和鼓包试验成型应用的实验结果进行比较,对确定的模型进行了验证。结果表明,实验观测结果与不稳定性的数值预测结果是一致的。
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引用次数: 0
An adaptive extended finite element based crack propagation analysis method 基于自适应扩展有限元的裂纹扩展分析方法
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.33301
Guizhong Xie, Chongmao Zhao, Hao Li, Jun Liu, Yudong Zhong, Wenliao Du, Jiahe Lv, Chao Wu
In this paper, a method of crack propagation analysis based on adaptive extension finite element is proposed. This method combines adaptive mesh reconstruction technology with extended finite element method (XFEM). Firstly, the model of engineering structure is discretized with the help of mesh generation software, and the initial mesh is divided. Secondly, Construction of XFEM model, and the tip of crack strengthening function is introduced to describe the physical field properties of the crack tip. The integral equation is solved to obtain the crack tip parameters. Then, the adaptive mesh reconstruction technology is built to refine the mesh of crack tip area through the error estimation of crack tip. Finally, the SIFs at the crack tip were calculated using the interaction integral, and the path direction of crack growth was determined using the maximum circumferential tensile stress criterion. Thus, the propagation path can be well traced.
本文提出了一种基于自适应扩展有限元的裂纹扩展分析方法。该方法结合了自适应网格重建技术和扩展有限元法(XFEM)。首先,利用网格生成软件将工程结构模型离散化,并划分初始网格。其次,构建 XFEM 模型,并引入裂纹尖端强化函数来描述裂纹尖端的物理场特性。通过积分方程求解得到裂纹尖端参数。然后,建立自适应网格重构技术,通过对裂纹尖端的误差估计来细化裂纹尖端区域的网格。最后,利用相互作用积分计算出裂纹尖端的 SIF,并利用最大圆周拉应力准则确定裂纹生长的路径方向。因此,可以很好地追踪裂纹的扩展路径。
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引用次数: 0
Notch Fatigue Property of 7050-T7451 Aluminum Alloy under Bending Resonance Environment 7050-T7451 铝合金在弯曲共振环境下的缺口疲劳特性
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.33709
Dingni He, Wei Cui, Yunfei Liao, Jianbo Zhang
Based on the electromagnetic shaker table, the resonant fatigue testing system and the corresponding conventional fatigue testing system were designed respectively. The fatigue life (S-N) curves of smooth and notched 7050-T7451 aluminum alloy specimens were measured in the range of 105-107 cycles, and the notch fatigue property of 7050-T7451 aluminum alloy under bending resonance environment was studied. The results indicate that the fracture mechanism under bending resonant fatigue environment is roughly the same as that under bending conventional fatigue loading. All the S-N curves obtained through resonant and conventional fatigue tests show a continuously downward trend, and there are no obvious fatigue limits. Notch fatigue property under bending resonance environment presents “stage characteristics”, which increases first and then decreases with the increase of cycles. There is a critical cycle number Nc at 8×105 cycles, corresponding to the maximum fatigue notch factor Kf-max (or the maximum notch sensitivity factor qmax). There are two critical cycles N1 and N2. When N1
以电磁振动台为基础,分别设计了共振疲劳试验系统和相应的传统疲劳试验系统。测量了 7050-T7451 铝合金光滑试样和缺口试样在 105-107 次循环范围内的疲劳寿命(S-N)曲线,研究了 7050-T7451 铝合金在弯曲共振环境下的缺口疲劳特性。结果表明,弯曲共振疲劳环境下的断裂机制与弯曲传统疲劳加载下的断裂机制大致相同。通过共振和常规疲劳试验获得的所有 S-N 曲线均呈持续下降趋势,且没有明显的疲劳极限。弯曲共振环境下的缺口疲劳特性呈现出 "阶段性特征",随着循环次数的增加,缺口疲劳特性先增大后减小。在 8×105 次循环时有一个临界循环数 Nc,对应于最大疲劳缺口系数 Kf-max(或最大缺口敏感系数 qmax)。有两个临界循环数 N1 和 N2。当 N1
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引用次数: 0
Kinematics and Trajectory Planning of 3-PSS/7R Spatial Hybrid Re-dundantly Driven Mechanism 3-PSS/7R 空间混合再驱动机构的运动学和轨迹规划
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.30862
Qisheng Zhang, Ruiqin Li, Jingjing Liang, Yao Wei
       A novel 3-PSS/7R spatial hybrid redundantly driven mechanism (HRDM) is proposed. The mechanism is driven by constant velocity (CV) motor and servo motor at the same time. The CV motor provides the main power for the system, and the servo motor plays the role of motion regulation. This system not only has the advantages of the traditional mechanical system, such as stable operation, large bearing capacity, but also can output controllable and adjustable flexible trajectory. The degrees of freedom of the mechanism are determined by the middle limb, which is called hybrid redundantly driven limb, which is driven by both CV motor and servo motor. Based on closed vector method, the position equation of the mechanism is established, and the velocity mapping matrix and acceleration change law of the mechanism are obtained. Further, the necessary and sufficient conditions for the mechanism to realize continuous trajectory and the relationship of rod constraints are obtained. The correctness of the kinematics equation and the smooth and controllable operation of the mechanism are verified by examples. The research results of this paper lay a foundation for the in-depth research and application expansion of spatial hybrid redundantly driven mechanism.
提出了一种新型 3-PSS/7R 空间混合冗余驱动机构(HRDM)。该机构由恒速(CV)电机和伺服电机同时驱动。CV 电机为系统提供主要动力,伺服电机起运动调节作用。该系统不仅具有传统机械系统运行稳定、承载能力大等优点,还能输出可控可调的柔性轨迹。机构的自由度由中间肢体决定,该肢体被称为混合冗余驱动肢体,由 CV 电机和伺服电机共同驱动。基于闭矢量法,建立了机构的位置方程,并得到了机构的速度映射矩阵和加速度变化规律。此外,还得到了机构实现连续轨迹的必要条件和充分条件,以及杆约束的关系。通过实例验证了运动学方程的正确性以及机构运行的平稳性和可控性。本文的研究成果为空间混合冗余驱动机构的深入研究和应用拓展奠定了基础。
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引用次数: 0
Modified proportional topology optimization algorithm for multiple optimization problems 针对多重优化问题的修正比例拓扑优化算法
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.34367
Xiong Rao, Run Du, Wenming Cheng, Yi Yang
Three modified proportional topology optimization (MPTO) algorithms are presented in this paper, which are named MPTOc, MPTOs and MPTOm, respectively. MPTOc aims to address the minimum compliance problem with volume constraint, MPTOs aims to solve the minimum volume fraction problem under stress constraint, and MPTOm aims to tackle the minimum volume fraction problem under compliance and stress constraints. In order to get rid of the shortcomings of the original proportional topology optimization (PTO) algorithm and improve the comprehensive performance of the PTO algorithm, the proposed algorithms modify the material interpolation scheme and introduce the Heaviside threshold function based on the PTO algorithm. To confirm the effectiveness and superiority of the presented algorithms, multiple optimization problems for the classical MBB beam are solved, and the original PTO algorithm is compared with the new algorithms. Numerical examples show that MPTOc, MPTOs and MPTOm enjoy distinct advantages over the PTO algorithm in the matter of convergence efficiency and the ability to obtain distinct topology structure without redundancy. Moreover, MPTOc has the fastest convergence speed among these algorithms and can acquire the smallest (best) compliance value. In addition, the new algorithms are also superior to PTO concerning suppressing gray-scale elements.
本文提出了三种修正比例拓扑优化(MPTO)算法,分别命名为 MPTOc、MPTOs 和 MPTOm。MPTOc 旨在解决具有体积约束的最小顺应性问题,MPTOs 旨在解决应力约束下的最小体积分数问题,而 MPTOm 旨在解决顺应性和应力约束下的最小体积分数问题。为了摆脱原有比例拓扑优化(PTO)算法的缺点,提高 PTO 算法的综合性能,提出的算法在 PTO 算法的基础上修改了材料插值方案,引入了 Heaviside 阈值函数。为了证实所提算法的有效性和优越性,求解了经典 MBB 梁的多个优化问题,并将原始 PTO 算法与新算法进行了比较。数值实例表明,与 PTO 算法相比,MPTOc、MPTOs 和 MPTOm 在收敛效率和获得无冗余的独特拓扑结构方面具有明显优势。此外,在这些算法中,MPTOc 的收敛速度最快,并能获得最小(最佳)的符合值。此外,新算法在抑制灰度元素方面也优于 PTO。
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引用次数: 0
Performance Analysis of Different Firearm Suppressor Structures 不同火器消音器结构的性能分析
Pub Date : 2024-02-23 DOI: 10.5755/j02.mech.35196
Vytautas Giedraitis, A. Kilikevičius
A powerful soundwave from shooting a firearm can travel great distances harming the shooter as well as anyone or anything standing nearby. To address this a firearm suppressor is used. A suppressor muffles the soundwave to a level that is usually safe for the shooter and its environment. A suppressor usually has 3-4 main parts that highly influence its effectiveness. The study aims to investigate how baffle design and placement selection influences the suppressor's effectiveness. The study consists of 162 different baffle design configurations. Suppressors with 3 to 9 baffles, angled from 30 to 60 degrees are simulated in a CFD environment. Slightly rounded baffles as well as different chamber volumes are tested as well. Suppressors with the best designs were then produced and tested on a firing range. At the firing range, a result of 32,24 dB delta was achieved and was only 4,67 % different than the result presented in the CFD study which was 30,8 dB respectively.  The 9 straight geometry baffle angled at 30 degrees suppressor with an average chamber volume proved to be the most efficient and combined with a large initial chamber was the most efficient design in this study.
枪支射击产生的强大声波可以传播很远的距离,对射击者以及站在附近的任何人或物造成伤害。为了解决这个问题,需要使用枪支消音器。抑制器可将声波消音到通常对射手和周围环境安全的程度。抑制器通常有 3-4 个主要部件,它们对抑制器的效果有很大影响。这项研究旨在调查障板设计和位置选择如何影响抑制器的效果。研究包括 162 种不同的障板设计配置。在 CFD 环境中模拟了 3 至 9 块障板、30 至 60 度角的抑制器。同时还测试了略呈圆形的障板以及不同的腔体容积。然后制作出具有最佳设计的抑制器,并在靶场上进行测试。在靶场上,测试结果为 32.24 dB delta,与 CFD 研究中的结果(分别为 30.8 dB)相比,仅相差 4.67%。 在这项研究中,9 个直形几何障板呈 30 度角,具有平均腔体容积的抑制器被证明是最有效的,结合大的初始腔体是最有效的设计。
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引用次数: 0
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Mechanics
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