Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

Lightweight Design of Commercial Vehicle Cab Based on Fatigue Durability

To better improve the lightweight and fatigue durability performance of the tractor cab,a multi-objective lightweight design of the cab was carried out in this study.First,the finite element model of the cab with counterweight loading was established and then confirmed by the physical testing,and use the inertial reliefmethod to obtain stress distribution under unit load.The cab-frame rigid-flexible couplingmulti-body dynamicsmodelwas built by Adams/car software.Taking the cab airbag mount displacement and acceleration signals acquired on the proving ground as the desired signals and obtaining the fatigue analysis load spectrum through Femfat-Lab virtual iteration.The fatigue simulation analysis is performed in nCode based on the Miner linear fatigue cumulative damage theory.Then,with themass and fatigue damage values as the optimization objectives,the bending-torsional stiffness and first-order bending-torsional mode as constraints,the thickness variables are screed based on the sensitivity analysis.The experimental design was carried out using the Optimal Latin hypercube method,and the multi-objective optimal design of the cab was carried out using theKriging approximationmodel fitting and particle swarmalgorithm.The weight of the optimized cab is reduced by 7.8%on the basis of meeting the fatigue durability performance.Finally,a seven-axis road simulation test rig was designed to verify its fatigue durability.The results show the optimized cab can consider both lightweight and durability.

A strategy for lightweight designing of a railway vehicle car body including composite material and dynamic structural optimization

Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.

Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

Application of Topology Optimization Technology based on Inspire and 3D Printing in Lightweight Design of Quadrotor UAV

This paper takes the fuselage bracket of the quadrotor UAV as the object,combined with the characteristics of less constraints in the 3D printing process,achieves the optimal structure of the UAV body structure design form,using the inspire topology optimization analysis,with the optimization goal of maximizing the overall stiffness and the optimized structure was checked for strength and verified by 3D printing prototype.The results show that under the premise of meeting the design strength and stiffness requirements,the mass is reduced by 53.29%compared with the original design.The research shows that the application of topology optimization and 3D printing technology to the structural design of UAVs will achieve significant weight reduction effects,providing a feasible way to realize lightweight,complex and integrated design and manufacturing of components.

Multi-Scale Design and Optimization of Composite Material Structure for Heavy-Duty Truck Protection Device

In this paper,to present a lightweight-developed front underrun protection device(FUPD)for heavy-duty trucks,plain weave carbon fiber reinforced plastic(CFRP)is used instead of the original high-strength steel.First,the mechanical and structural properties of plain carbon fiber composite anti-collision beams are comparatively analyzed from a multi-scale perspective.For studying the design capability of carbon fiber composite materials,we investigate the effects of TC-33 carbon fiber diameter(D),fiber yarn width(W)and height(H),and fiber yarn density(N)on the front underrun protective beam of carbon fiber compositematerials.Based on the investigation,a material-structure matching strategy suitable for the front underrun protective beam of heavy-duty trucks is proposed.Next,the composite material structure is optimized by applying size optimization and stack sequence optimization methods to obtain the higher performance carbon fiber composite front underrun protection beam of commercial vehicles.The results show that the fiber yarn height(H)has the greatest influence on the protective beam,and theH1matching scheme for the front underrun protective beamwith a carbon fiber composite structure exhibits superior performance.The proposed method achieves a weight reduction of 55.21% while still meeting regulatory requirements,which demonstrates its remarkable weight reduction effect.

Lightweight Design and Verification of Gantry Machining Center Crossbeam Based on Structural Bionics

The lightweight and high efficiency of natural structures are the inexhaustible sources for engineering improvements. The goal of the study is to find innovative solutions for mechanical lightweight design through the application of structural bionic approaches. Giant waterlily leaf ribs and cactus stem are investigated for their optimal framework and superior performance. Their structural characteristics are extracted and used in the bio-inspired design of Lin MC6000 gantry machining center crossbeam. By mimicking analogous network structure, the bionic model is established, which has better load-carrying capacity than conventional distribution. Finite Element Method （FEM） is used for numerical simulation. Results show better specific stiffness of the bionic model, which is increased by 17.36%. Finally the scaled models are fabricated by precision casting for static and dynamic tests. The physical experiments are compared to numerical simulation. The results show that the maximum static deformation of the bionic model is reduced by about 16.22%, with 3.31% weight reduction. In addition, the first four natural frequencies are improved obviously. The structural bionic design is a valuable reference for updating conventional mechanical structures with better performance and less material consumption.

Lightweight Design of Automobile Drive Shaft Based on the Characteristics of Low Amplitude Load Strengthening

There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.

The Lightweight Design of Low RCS Pylon Based on Structural Bionics

A concept of Specific Structure Efficiency (SSE) was proposed that can be used in the lightweight effect evaluation ofstructures.The main procedures of bionic structure design were introduced systematically.The parameter relationship betweenhollow stem of plant and the minimum weight was deduced in detail.In order to improve SSE of pylons, the structural characteristicsof hollow stem were investigated and extracted.Bionic pylon was designed based on analogous biological structuralcharacteristics.Using finite element method based simulation, the displacements and stresses in the bionic pylon were comparedwith those of the conventional pylon.Results show that the SSE of bionic pylon is improved obviously.Static, dynamic andelectromagnetism tests were carried out on conventional and bionic pylons.The weight, stress, displacement and Radar CrossSection (RCS) of both pylons were measured.Experimental results illustrate that the SSE of bionic pylon is markedly improvedthat specific strength efficiency and specific stiffness efficiency of bionic pylon are increased by 52.9% and 43.6% respectively.The RCS of bionic pylon is reduced significantly.

Compact Car-Body Surface Design with T-spline Surface

Creating proper B-spline surface models is a very challenging task for designers in car-body surface design.Due to the tensor-product structure of B-spline surface,some undesirable issues of the redundant control points addition,incomplete surface definition and the difficulty of trimming boundary alteration frequently occur,when designing the car-body surface with B-spline surfaces in local-feature-lines construction,full-boundary-merging and visual surface trimming.A more efficient approach is proposed to design the car-body surface by replacing B-spline surface with classical T-spline surface.With the local refinability and multilateral definition offered by Tspline surface,those designing issues related with B-spline surface can be overcomed.Finally,modeling examples of the door,hood and rear-window are given to demonstrate the advantage of T-spline surface over B-spline surface in car-body surface design.

Lightweight design of 45000r/min spindle using full factorial design and extreme vertices design methods

Factors for determining the spindle size are the shaft diameter,positions of bearing and motor,and entire length of the spindle.Then,it is important to find the assembling of the optimal design variables,which satisfy the stiffness and rotational speed required to the spindle.A general full factorial design method was used to verify some factors that affect the natural frequency of a spindle.It is verified that the shorter shaft length and bearing span length represent the higher natural frequency,and there are some effects according to the change in the levels of factors.The detailed spindle dimension is determined by applying an EVD method,which can define the optimal bearing position through considering the limiting condition.Based on the estimated regression model,the optimal spindle size and bearing distance that can improve the primary natural frequency are obtained,and the influence of design factors on the natural frequency is also analyzed.

Lightweight design technology of planet carrier for wind turbine gearbox

A finite element model of one-arm planet carrier was built, and influence of structural parameters on strength and stiffness for one-arm planet carrier was analyzed. The stress and deformation of the round structure and the triangle structure for one-arm planet carrier were analyzed and compared. The finite element model of the same specifications arms planet carrier was established, and influence of the connecting slab thickness and input side plate thickness on strength and stiffness for arms planet carrier was analyzed. Strength, stiffness and mass for one-arm and arms planet carrier in the same specifications were analyzed and compared.

DESIGN OF LIGHTWEIGHT PUF CIRCUIT BASED ON SELECTABLE CROSS-COUPLED INVERTERS

By analyzing the principle of process variations, a lightweight Physical Unclonable Function(PUF) circuit based on selectable cross-coupled inverters is proposed in this paper. Firstly, selectable cross-coupled inverters are chosen for two delay paths. Simultaneously, the circuit takes challenge signal to control each delay path. The PUF cell circuit is implemented in Semiconductor Manufacturing International Corporation(SMIC) 65 nm CMOS technology and the layout area is 2.94 mm × 1.68 mm. Then the 64-bit PUF circuit is achieved with the cascade connection of cell circuits. The simulation results show that the randomness is 49.4% and the reliability is 96.5%. Compared to the other works, this PUF circuit improves the encrypt performance and greatly reduces the area.

Research on Lightweight Design of Automobile Lower Arm Based on Carbon Fiber Materials

Based on the principle of lightweight design, a method of using carbon fiber reinforced composite instead of traditional metal materials to design automobile carrier?can be?proposed. The method uses the equal stiffness design principle of the composite material parts to lay out the design of the carbon fiber parts, including the application of the laying angle and the thickness of the laying layer in design. Through the analysis of the actual working conditions of the lower arm, the stress and boundary conditions are obtained. After the design of the stiffness, the geometrical topology of the lower arm is further optimized. Finally, the lower arm of the carbon fiber not only met the performance requirements,?but also to a certain extent, achieved?the purpose of lightweight.

Configuration Synthesis and Lightweight Networking of Deployable Mechanism Based on a Novel Pyramid Module

Deployable mechanism with preferable deployable performance,strong expansibility,and lightweight has attracted much attention because of their potential in aerospace.A basic deployable pyramid unit with good deployability and expandability is proposed to construct a sizeable deployable mechanism.Firstly,the basic unit folding principle and expansion method is proposed.The configuration synthesis method of adding constraint chains of spatial closed-loop mechanism is used to synthesize the basic unit.Then,the degree of freedom of the basic unit is analyzed using the screw theory and the link dismantling method.Next,the three-dimensional models of the pyramid unit,expansion unit,and array unit are established,and the folding motion simulation analysis is carried out.Based on the number of components,weight reduction rate,and deployable rate,the performance characteristics of the three types of mechanisms are described in detail.Finally,prototypes of the pyramid unit,combination unit,and expansion unit are developed to verify further the correctness of the configuration synthesis based on the pyramid.The proposed deployable mechanism provides aference for the design and application of antennas with a large aperture,high deployable rate,and lightweight.It has a good application prospect in the aerospace field.

动车组应急蓄电池箱的多目标优化

针对动车组的应急蓄电池箱的安全问题和轻量化设计要求,综合多个优化目标对其进行优化分析。将主要部件的厚度作为设计变量,以应急蓄电池箱的总质量和和恶劣工况下的应力最小为优化目标,以其第1阶固有频率为约束函数,使用Box-Behnken设计方法获取样本数据。利用样本数据建立低阶多项式响应面模型,结合第三代非支配排序遗传算法(NSGA-Ⅲ)进行多目标优化。结果表明:相较于单一的响应面法或遗传算法,本文采用的响应面法与遗传算法结合的方式,使得优化后的参数更加合理,轻量化和安全性均得到了保障。

应力驱动的2.5D梯度各向异性维诺多孔零件轻量化建模方法

为了提高多孔零件的设计自由度、内部力学性能梯度与实际应力分布的匹配度,提出一种应力驱动的2.5D梯度各向异性维诺多孔零件轻量化设计方法。将零件有限元分析结果分解为应力标量场和应力方向场,通过加权随机采样算法将应力标量场映射为零件设计域内的维诺站点分布,实现零件内部力学性能的梯度分布;将应力方向场映射为二维黎曼流形,提出一种基于胞元择优方向生长策略的各向异性维诺图生成算法,生成胞元沿黎曼流形分布的各向异性维诺图。在此基础上,通过偏置算法、调和距离场和拉伸算法生成光滑的梯度各向异性维诺多孔零件。最后,采用有限元分析、三点弯曲实验等方法将所设计的多孔零件和其他多孔零件进行比较分析。实验结果表明,所提出的梯度各向异性维诺多孔零件建模方法能有效提升零件内部力学性能梯度与实际应力分布的匹配度,降低材料消耗,实现轻量化设计。

武器装备轻量化结构正向设计方法及应用

为满足武器装备轻量化的迫切需求,提升装备结构优化设计水平,提出了一种代理模型辅助多目标优化的结构正向设计方法。按照从概念设计到参数优化设计的流程,通过优化信息交互和代理模型重构来实现结构多目标优化设计。以轻型车载高炮弹箱架优化设计为例,首先,根据拓扑优化获得的最佳传力路径,建立几何模型和有限元分析模型。其次,通过灵敏度分析缩减设计变量,建立以一阶模态频率和结构强度为约束、最小化质量和最大化刚度为目标的优化模型。然后,使用差分进化算法求解基于Kriging模型的多目标优化问题;在优化过程中,通过比较中间优化结果调整优化模型,并采用基于期望改进的填充样本策略重构代理模型。最后,兼顾结构轻量化和安全,筛选44组优化解中的3组优势方案与初始设计进行比较,结果显示:在满足弹箱架结构性能的前提下,重量分别可减轻31.2%、24.7%和21.8%;所提结构正向设计方法能够明显提升轻量化效果,也可为相关结构优化设计提供参考。

针对嵌入式设备的YOLO目标检测算法改进方法

针对算法在资源有限的嵌入式设备实现困难的问题,本文基于YOLO系列算法提出适应嵌入式设备实现的轻量化改进方法。方法具体包括:基于YOLOv4-Tiny算法结构,引入GhostNet思想改进其网络主干,大量降低网络参数量和计算量;通过加强颈部网络特征融合效果,减少模型压缩导致的精度损失;采用训练中量化的方式将网络模型参数从32位浮点型数据转换为适合嵌入式设备计算的8位定点型参数。实验结果表明,改进后的网络在检测精度满足应用要求的情况下,模型尺寸相对原算法降低57%,在嵌入式设备上实现功耗仅3.795W。

轻量化高速列车制动盘材料-结构研究进展

400 km/h高速列车紧急制动的强热负荷,导致制动盘温升高、温度分布梯度大和热衰减强,已超出钢质制动盘能载极限,开发耐高温强耐磨的制动盘材料,同时提升制动盘通风散热能力成为制动技术发展瓶颈。综述高速制动盘材料从高强度铸钢和锻钢、轻量化铝基复合材料至耐高温耐磨碳陶复合材料和表面改性技术发展历程,随着碳陶复合材料的台架试验和表面改性技术的摩擦磨损试验研究的深化,表面改性轻质复合材料是制动盘材料未来发展方向。概述通风制动盘内部散热层散热筋结构形貌优化、摩擦层表面耐磨性能改善的发展现状,内部散热筋由直通道设计逐渐演化为弯曲、支柱以及分形通道,镂空结构能更好地加速空气流动提高散热;表面摩擦层引入打孔或划线,更易于摩擦粉尘的抛离从而稳定摩擦因数,保持制动效果;但复杂通风导流结构和打孔划线增加了制备工艺的难度,提出高速制动盘结构构型设计需要综合材料热力学性能、制备工艺及耐热耐磨需求,形成材料-结构-功能—体化设计理念,为实现更高速的制动盘优化设计提供参考。