• In metal joining processes across various industries, welding is a critical part of overall production. The welding involved is not only diverse in type, with numerous weld seams and complex welded structures, but most weld seams are multi-layer multi-pass welds, which makes welding deformation of parts difficult to control throughout the entire welding process.

  Therefore, for a long time, the improvement and optimization of welding processes have mainly relied on the experience of process engineers and various process tests, and there has long been a lack of a professional and effective method and means. With the development of computer technology and the gradual maturity of finite element theory, welding simulation technology has begun to become a good method and means in the process of welding process optimization and improvement.

• 在各行业中涉及到金属连接的部分，焊接是整个生产中非常关键的一环，涉及到的焊接不仅种类多、焊缝多、焊接结构复杂，且大部分焊缝均为多层多道焊，这就导致了在整个焊接过程中，零件的焊接变形难以控制。
• 因此长期以来，对于焊接工艺的改进和优化主要依靠工艺人员的经验和各类工艺试验，一直缺乏一套专业的有效的方法和手段。随着计算机技术的发展和有限元理论的逐渐成熟，焊接模拟仿真技术已经开始成为在焊接工艺优化改进过程中的良好手段和方法。

Seats and head restraints are tested on a sled using a low speed rear-impact dummy. Three dynamic tests are done, representing common accident severities known to cause injuries, together with an assessment of the geometry of the front and rear head restraints.

• Using the finite element method, it is a key technology for virtual validation of performance such as stiffness, strength, modal characteristics, durability, and crash safety during the R&D stage. By establishing a high-precision finite element model, the response of the instrument panel under static load, dynamic vibration, and temperature variation conditions can be simulated, identifying design defects in advance and guiding optimization. This technology can effectively shorten the development cycle and reduce testing costs, and is a core means to improve the structural reliability and safety of the instrument panel assembly.
• 运用有限元方法，在研发阶段对其刚度、强度、模态、耐久及碰撞安全等性能进行虚拟验证的关键技术。通过建立高精度有限元模型，可模拟仪表板在静态载荷、动态振动及温度变化等工况下的响应，提前识别设计缺陷并指导优化。该技术能有效缩短开发周期、降低试验成本，是提升仪表板总成结构可靠性与安全性的核心手段

The Adult Occupant Protection score is determined from frontal impact, side impact and whiplash tests, which are carried out to evaluate the protection of adult driver and passengers offered by the vehicle. 

1-1 Full Width Rigid Barrier-FRB
Cars against a rigid barrier with full overlap at a test speed of 50km/h. A small female frontal impact dummy is seated in the front driver’s seat and in the rear passenger side seat.

1-2 Offset-Deformable Barrier – ODB
In the full-scale test, the car is driven at 64km/h and with 40 percent overlap into a deformable barrier which represents the oncoming vehicle. The test replicates a crash between two cars of the same weight, both travelling at a speed of 50km/h. Two frontal impact dummies representing the average male are seated in the front and child dummies are placed in child restraints in the rear seats.

1-3 Side Mobile Barrier
A deformable barrier is mounted on a trolley and is driven at 50km/h into the side of the stationary test vehicle at right angles. A side impact dummy representing an average male is put in the driver’s seat and child dummies are placed in child restraint systems in the rear.

1-4 Side Pole
A car is propelled sideways at 32km/h against a rigid, narrow pole. The car is placed at right angles to the direction of motion, or as is done from 2015 onwards, at a small angle away from the perpendicular. A single average male side impact dummy is placed in the driver’s seat.

The Pedestrian Protection score is determined from tests to the most important vehicle front-end structures such as the bonnet and windshield, the bonnet leading edge and the bumper. In these tests, the potential risk at injuries to pedestrian head, pelvis, upper and lower leg are assessed.

Head impact
Most pedestrian accidents occur within city areas where speeds are moderate. The head, the lower body and the legs are amongst the most frequently injured body regions. To estimate the potential risk of head injury in the event of a vehicle striking an adult or a child, a series of impact tests is carried out at 40 km/h using an adult or child head form impactor. Impact sites are then assessed and the protection offered is rated as good, adequate, marginal, weak or poor.The procedure promotes energy absorbing structures, deformation clearance and deployable protection systems such as pop-up bonnets and external airbags.

Upper Leg Impact
To estimate the potential risk of pelvis and upper leg injuries in the event of a vehicle striking an adult, a series of impact tests is carried out at 40 km/h using an adult upper leg form impactor. Impact sites are then assessed and the protection offered is rated as good, adequate, marginal, weak or poor.The procedure promotes energy absorbing structures and a more forgiving geometry that mitigates injuries.

Lower Leg Impact
To estimate the potential risk of leg injuries in the event of a vehicle striking an adult, a series of impact tests is carried out at 40 km/h using an adult leg form impactor. Impact sites are then assessed and the protection offered is rated as good, adequate, marginal, weak or poor. The procedure promotes energy absorbing structures and a more forgiving geometry that mitigates injuries to the leg.

• More than 1,000 children die in traffic accidents in Europe every year. Nearly half of all fatal child accidents occur when children are occupants of motor vehicles.

  Vehicle manufacturers are legally obliged to provide information on the use of child restraint systems on vehicle seats. NCAP checks the suitability of different child restraint systems and verifies the protection provided by recommended child restraint systems in frontal or side impact events.

  Initially, child dummies simulating children aged 1.5 to 3 years were placed in child restraint systems recommended by the vehicle manufacturer on the rear seats. In 2016, the test configuration changed, and the test was changed to place child dummies simulating children aged 6 to 10 years on booster seats or cushions.

  The dummy’s head movement, neck load, and chest acceleration are the main measurement indicators during the test. If the test indicators remain at a low level, and the dummy does not bounce off the seat or violently impact the vehicle interior during the collision, the vehicle will receive an award. This ensures that children are always properly restrained in a collision event.

• 欧洲每年有超过 1,000 名儿童死于交通事故。 几乎有一半的儿童致命事故都是在儿童作为机动车乘员的情况下发生的。
  车辆制造商在法律上有义务提供关于在车辆座位上使用儿童约束装置的信息。NCAP会检查不同儿童约束装置的合适程度，同时验证在正面或侧面碰撞事件中推荐的儿童约束装置所提供的保护。
  最初，模拟 1 岁半至 3 岁儿童的儿童假人被安放在汽车后排座椅上由汽车制造商推荐的儿童约束装置中。2016 年，试验配置发生了改变，试验改为将模拟 6 至 10 岁儿童的儿童假人安放在防护座椅或坐垫上。
  假人的头部运动、颈部承重和胸部加速度是试验过程中的主要测量指标。如果试验指标保持较低水平，并且碰撞过程中假人未从座椅上弹起或不会与车辆内部猛烈撞击，则该车辆将获奖项。这可以确保儿童在碰撞事件中始终受到正确的约束。

• As an important connection between occupants and the vehicle, automotive seats play a particularly important role in occupant safety. Reasonable seat structural design can ensure that the seat meets certain strength requirements under complex load conditions, absorbs more collision energy while ensuring functions do not fail, and effectively reduces the degree of occupant injury during collisions.

  Based on the seat of a certain brand of automobile, finite element simulation analysis methods are used to study its safety performance. The main work is as follows: First, the CAD digital model of the seat is discretized, and components such as the frame, height adjuster, and slide rails are carefully meshed to obtain a detailed structural model. The materials and properties of each component are determined according to real material characteristics, and reasonable connection methods are selected to ensure simulation accuracy.

  Second, HyperMesh and Primer are used as pre-processors, LS-DYNA, Nastran, and Abaqus as solvers, and HyperView as the post-processor. According to the test conditions specified in domestic regulations GB 15083-2006, GB 11550-2009, and GB 14167-2006, as well as the 2021 version of China New Car Assessment Program (C-NCAP), relevant parameters are set and corresponding boundary conditions are defined. Simulation models are established for the modal test, headrest energy absorption test, seat back static strength test, seat static strength test, seat inertia resistance test, seat belt anchorage strength test, ISOFIX anchorage strength test, luggage impact test, and whiplash test.

• 汽车座椅作为乘员和汽车的重要连接纽带,对乘员的安全起到尤为重要的作用。合理的座椅结构设计,能够确保座椅在承受复杂载荷的条件下满足一定的强度要求,能够在保证功能不失效的前提下吸收更多的碰撞能量,能够有效地减轻碰撞过程中乘员的损伤程度。
• 基于某品牌汽车的座椅,运用有限元仿真分析方法,对其安全性能进行研究,主要工作如下: 首先,对座椅的CAD数模进行离散化处理,对骨架、高度调节器及滑轨等零部件进行细致地划分,得到详细的结构模型。根据真实的材料特性确定各零部件的材料及其属性,并选择合理的连接方式保证仿真的精度。 
• 其次,运用Hypermesh和Primer作为前处理器,LS-Dyna、Nastran以及Abaqus为求解器,Hyperview为后处理器。依据国内法规GB15083-2006、GB11550-2009和GB14167-2006以及2021版中国新车评价规程(C-NCAP,China New Car Assessment Program)规定的试验条件设置相关的参数,定义相应的边界条件,建立模态试验、头枕能量吸收性试验、靠背静强度试验、座椅静强度试验、座椅抗惯性试验、安全带固定点强度试验、ISOFIX固定点强度试验、行李箱冲击试验以及鞭打试验的仿真模型。

• CAE finite element simulation analysis of automotive mirrors is a key digital means to verify their structural performance and safety reliability. The process first establishes a high-precision finite element mesh model including components such as the mirror housing, mirror bracket, base, and folding mechanism based on the 3D geometric model, and accurately assigns material properties to each component (such as elastic modulus, Poisson’s ratio, and yield strength).

  The simulation mainly covers several core load cases: simulating the wind pressure load on the mirror body during high-speed vehicle driving, evaluating whether its deformation affects the field of view and whether the stress at the bracket root exceeds the limit; according to regulatory requirements, simulating the folding and return process of the mirror body around its axis under external force, analyzing the durability damage of the rotating shaft and limit structure; in addition, modal analysis is included to avoid resonance with engine or road excitation frequencies. Through solving and calculation, the stress distribution and fatigue life of dangerous areas can be accurately predicted. The simulation results not only guide lightweight product design and reduce physical trial and error, but are also the core basis for ensuring that mirrors meet mandatory standards such as vibration durability, impact resistance, and aerodynamic performance, significantly shortening the development cycle and reducing costs.

• 汽车后视镜的CAE有限元仿真分析是验证其结构性能与安全可靠性的关键数字化手段。该过程首先基于三维几何模型，建立包含镜壳、镜托、基座及折叠机构等部件的高精度有限元网格模型，并准确赋予各部件材料属性（如弹性模量、泊松比及屈服强度）。
• 仿真主要涵盖多个核心工况：模拟车辆高速行驶时镜体承受的风压载荷，评估其变形量是否影响视野及支架根部应力是否超限；依据法规要求，模拟镜体在外力作用下的绕轴折叠与回位过程，分析转轴及限位结构的耐久损伤；此外，还包括模态分析以避免与发动机或路面激振频率共振。通过求解计算，可精准预判危险区域应力分布与疲劳寿命。仿真结果不仅指导产品轻量化设计，减少实物试错，更是确保后视镜满足振动耐久、抗冲击及空气动力学性能等强制性标准的核心依据，显著缩短了开发周期并降低了成本。

• Noise, Vibration, and Harshness (NVH) is the English abbreviation for Noise, Vibration, and Harshness. This is a comprehensive issue in measuring automotive manufacturing quality, and it gives car users the most direct and superficial perception. Vehicle NVH issues are one of the concerns of major vehicle manufacturers and component companies in the international automotive industry. According to statistics, about one-third of vehicle failure problems are related to vehicle NVH issues, and major companies spend nearly 20% of their R&D expenses on solving vehicle NVH problems. NVH issues are systematic. For example, some cars have loud cabin noise while driving, and the source is traced to the engine. Then this noise problem may involve three parts: one is the loud noise of the engine itself, one is the poor vibration damping effect of the engine mounting components, and one is the poor sound insulation technology of the cabin front wall and floor. It is an interrelated system problem.
• 噪声、振动与声振粗糙度（Noise、Vibration、Harshness）的英文缩写。这是衡量汽车制造质量的一个综合性问题， 它给汽车用户的感受是最直接和最表面的。车辆的NVH问题是国际汽车业各大整车制造企业和零部件企业关注的问题之 一。有统计资料显示，整车约有1/3的故障问题是和车辆的NVH问题有关系，而各大公司有近20%的研发费用消耗在解决 车辆的NVH问题上。NVH问题是系统性的。例如有些轿车行驶时车厢噪声大，查源头在发动机，那么这一个噪声问题可能 就涉及到三个部分，一个是发动本身的噪声大，一个是发动机悬置部件减振效果差，一个是车厢前围和地板隔音技术不 好，是一个互相关连的系统问题。

• At present, the research and analysis methods of fluid mechanics are divided into three types: theoretical analysis, experimental research, and numerical calculation. The theoretical analysis method is based on studying the laws of fluid motion, establishing various simplified flow models, and forming various types of governing equations that describe the flow; under certain assumptions and conditions, through analytical derivation and calculation, the analytical solution or simple solution of the problem is obtained.

  For a long time, experimental research has been the main research method in fluid dynamics. Its principle is to use the principle of relative motion to establish ground experimental facilities, such as water tunnels, water channels, wind tunnels, and shock tubes, to obtain relevant data. However, experimental research is generally completed under simulated conditions. Almost all ground experimental facilities cannot fully satisfy all similarity parameters and similarity law requirements. Moreover, in addition to wall effects, support interference, and measurement errors, experiments also face factors that are very difficult to simulate, such as the non-equilibrium effects of real gases in hypersonic flow. Therefore, experimental research is also subject to many limitations. Generally speaking, experimental research has a long cycle and high cost.

  Computational Fluid Dynamics, abbreviated as CFD, is a specialized discipline that uses computers and numerical methods to solve fluid dynamics equations satisfying definite solutions, so as to obtain flow laws and solve flow problems. As a specialized discipline, computational fluid dynamics was roughly formed in the 1960s. Now CFD has penetrated into technical fields related to flow.

• 目前，流体力学的研究和分析手段分为理论分析、实验研究及数值计算三种。理论分析的方法是在研究流体运动规律 的基础上，建立各种简化的流动模型，形成描述流动的各类型控制方程；在一定假设和条件下，经过解析推导及运算， 得到问题的解析解或简单解。
• 长期以来，实验研究一直是流体动力学的主要研究手段， 其原理是利用相对运动原理，建立地面实验设备，如水洞、水槽、风洞、激波管等获得相关数据。但是，实验研究一般 是在模拟条件下完成的，几乎所有的地面实验设备都不能完全满足所有相似参数、相似定律要求，而且实验除了存在洞 壁效应、支架干扰、测量误差等外，还存在高超声速流动中真实气体的非平衡效应等很难模拟的因素，所以实验研究也 受到不少限制。一般来说，实验研究周期长、费用高。
• 计算流体动力学(Computational Fluid Dynamics)，简称CFD。它是利用计算机和数值方法求解满足定解的流体动力学方程,以获得流动规律和解决流动问 题的专门学问。计算流体动力学作为一门专门学科，大约是20世纪60年代形成的。现在CFD已深入到与流动有关的技术领 域。