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1. 研究目的与意义（文献综述）
1. Design purpose and significance
1.1 Design purpose and significance
Suspension is an important assembly of automobile, which connects frame (or body) with axle (or wheel) elastically. Its function is to transfer all the forces or moments between the wheel and the frame (or body) and to alleviate the impact load from the uneven road surface to the frame (or body), attenuate the vibration caused by it and ensure the smooth running of the car. The suspension is mainly composed of elastic elements, guiding mechanism and shock absorber. Some suspensions also have buffer blocks and lateral stabilizers. Independent suspension and non-independent suspension are common suspensions in two-axle automobiles, while independent suspension is the main suspension in modern automobiles. With the development of automotive industry, the demand for comfort, handling and stability of automobile is increasing. Among many kinds of suspension, multi-link independent suspension has become the main suspension structure used in the rear suspension of mid-class and high-class cars by virtue of its excellent performance. [4] In independent suspension, single longitudinal arm and single oblique arm independent suspension are simple in structure and low in cost. They are often used in rear suspension, but there are still some shortcomings such as small lateral stiffness and small roll angle stiffness. This design is the rear suspension design of Toyota's eighth generation Camry. The eighth generation of Camry is based on TNGA, and has redeveloped almost all parts to make it a genuine and thorough new replacement model. Honda chose McPherson independent suspension on the front suspension and double-arm independent suspension on the rear suspension. This design chooses multi-link independent suspension on the rear suspension to obtain the best location of the kingpin caster angle, and minimize the forward and backward direction force to ensure the stability of normal driving, and also improve the ride comfort and comfort when the speed changes. By designing the constraint angle connecting the moving points, the wheel alignment can be adjusted actively when the suspension is compressed, so as to improve the control limit of the vehicle. By reasonably configuring the positions of the connecting rods of the suspension, the suspension can actively adjust the wheel alignment when it jumps, and the design freedom is large. The structure of multi-link suspension is complex, and the cost of material, research and development and manufacturing are much higher than other types of suspension, which occupies large space. However, the comfort of the multi-link suspension is the best of all suspensions, and its maneuverability is similar to that of the double-arm independent suspension.
The lightweight of automobiles of reducing the quality of automobiles as much as possible under the premise of guaranteeing the strength and safety performance of automobiles, so that to improve the power of automobiles, reduce the fuel consumption and reduce exhaust pollution.
2. 研究的基本内容与方案
2.The basic content and scheme of the design
When designing a suspension for a vehicle, engineers will fully consider the structure, price, location and cost control of the vehicle. Each kind of suspension has its own advantages and disadvantages, but there are many advantages and disadvantages. At the same time, different suspensions have a great impact on the performance of vehicles, leading to strong mobility and comfort.
2.1 Leaf spring type non-independent suspension
Longitudinal leaf spring independent suspension is a suspension which uses leaf spring as an elastic element and is arranged parallel to the longitudinal axis of the vehicle. It also acts as a guide mechanism, which simplifies the suspension system. It is commonly used in commercial vehicles, such as trucks, pickups, vans, etc.
Generally, we also call this kind of suspension "slab car suspension". Of course, there is another kind of slab suspension - torsion beam semi-independent suspension.
2.2 Torsion beam semi-independent suspension
Torsional beam semi-independent suspension, also known as towed arm suspension, is often nicknamed as "scooter suspension", unlike leaf spring non-independent suspension, which is mostly used in the rear suspension of passenger cars. Generally, we divide the suspension into independent suspension and non-independent suspension, but the torsion beam semi-independent suspension is special. From the structure, it should belong to the variety of beam non-independent suspension, but from the performance, it has the performance of full-towed independent suspension with higher stability. Therefore, we call it torsion beam semi-independent suspension.
2.3 Double fork arm type independent suspension
Double fork arm independent suspension, also known as double A arm independent suspension. Front suspension uses double wishbone and lateral stabilizer, which is called "double wishbone", but in fact it is a simplified version of double wishbone.
2.4 McPherson Independent Suspension
McPherson independent suspension is one of the most widely used front suspensions of cars in the world today. Most of the car front suspensions seen in the market use this kind of suspension. The McPherson suspension is actually a simplified version of the double-arm suspension, which consists of a helical spring, shock absorber and triangular lower swing arm. Most of the models also have lateral stabilizers.
2.5 Multi-link Independent Suspension
Multi-link suspension refers to a suspension structure consisting of three or more connecting rods, which can provide control forces in multiple directions, so that the tire has a more reliable trajectory. But now most models use four-link and five-link forms to enhance the performance of vehicles. Multi-link suspension can achieve the best position of kingpin caster Angle, greatly reduce the front and rear direction force from the road surface, thus improving the smoothness and comfort of acceleration and braking, while ensuring the stability of straight-line driving, because the lateral displacement of wheel caused by the stretching or compression of coil spring is very small, and it is not easy to cause non-straight-line driving.
3. 研究计划与安排
3. Schedule
| The first week | Collect design materials for graduation practice |
| The second week—The third week | graduation field work |
| The fourth week | Prepare the opening report |
| The fifth week—The sixth week | Calculate each design parameter |
| The seventh week—The eighth week | Product CATIA model |
| The ninth week—The tenth week | Drawing the overall layout of the suspension system |
| The eleventh week—The twelfth week | Draw assembly drawing and component drawing of leaf spring component |
| The thirteenth week—The third week | Design specification |
| The fourteenth week | Graduation thesis defense |
4. 参考文献（12篇以上）
1.王晓波，李晓雷.独立多连杆悬架优化设计方法研究【D】，北京理工大学，2016.6
多连杆独立悬架凭借其优越的性能已经成为了轿车上应用的主流悬架形式，而国内的相关研究和开发设计却是寥寥，论文从多个方面对独立多连杆悬架优化设计方法进行了研究。构理论分析上建立几何模型，进行硬点布置设计，编写MATLAB代码，评价模型方案；多体动力学上，实测某种车型，在ADAMS/CAR软件中建立两个多连杆悬架系统，硬点布置参数不同，通过仿真实验和对比研究，完成KC特性分析；在优化设计方法上，在设计域中进行多目标优化，最终取得较为理想的优化结果。
2.田罗，何耀华.多连杆式独立悬架参数化建模及优化设计【D】，武汉理工大学，2012.6
悬架是汽车的重要总成，是传递作用在车身和车轮之间各种力和力矩的重要机械装置，对汽车的稳定性、平顺性等多种性能具有重要影响。论文利用动力仿真软件ADAMS研究分析了优化后的悬架系统对整车性能的影响。基于ADAMS/Car平台，在双横臂独立悬架的模板基础上，设计五连杆独立后悬架，并进行运动学仿真实验分析，根据车轮定位参数图，对悬架进行优化设计。再优化后的后悬架基础上，建立整车模型，并在标准ISO4138--2004下进行操纵稳定性分析。
3.杨绍勇，韩旭.复合材料悬架控制臂结构轻量化设计【D】，湖南大学，2017,.5
悬架控制臂的轻量化设计是汽车底盘的重要研究内容，复合材料凭借其优秀的材料性能，具有很大的研究意义。论文分别从复合材料控制臂几何结构设计、铺层优化设计以及胶-螺连接结构设计等方面展开研究。以钢质悬架控制臂为参考，运用多体动力学分析其在几种行驶工况下的载荷情况，然后分析控制臂的刚度、强度以及固有频率等性能指标。然后完成复合材料控制臂的几何结构设计、铺层设计，提高性能指标水平，建立胶-螺混合连接的有限元模型，对比已有研究成果验证模型。
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