Leaf springs are crucial suspension elements used on light and heavy passenger vehicle necessary to minimize the vertical vibrations impacts and bumps due to road irregularities and to create a comfortable ride.Leaf springs are widely used for automobile and rail road suspensions. It consists of series of flat plates,usually of semi- elliptical shapes. The leaves are held together by means of two U-bolts and a center clip.Rebound clips are provided to keep the leaves in alignment and prevent lateral shifting of the plate during the operation. The longest leaf called the master leaf is bent at both ends to form a spring eye. At the center, the spring is fixed at the axel of the vehicle.Multileaf springs are provided with one or two extra full-length leaves in addition to the master leaf. This extra full-length leaves are stacked between the master leaf and the graduated length leaves. The extra full length leaves are provided to support the transverse shear force. The leaf spring should absorb the vertical vibrations and impacts due to road irregularities by means of variations in the spring deflection so that the potential energy is stored in spring as strain energy and hen released slowly so increasing the energy storage capabilities of a leaf spring and ensures a more compliant suspension system.
A spring is defined as an elastic body, whose function is to distort when loaded and to recover its original shape when the load is removed. Leaf springs absorb
the vehicle vibrations, shocks and bump loads induced due to road irregularities by means of spring deflections, so that the potential energy is stored in the leaf spring and then relieved slowly. Ability to store and absorb more amount of strain energy ensures the comfortable suspension system. Semi-elliptic leaf springs are almost universally used for suspension in light and heavy commercial vehicles. For cars also,these are widely used in rear suspension. The spring consists of a number of leaves called blades. The blades are varying in length. The blades are us usually given an initial curvature or cambered so that they will tend to straighten under the load. The leaf spring is based upon the theory of a beam of uniform strength. The lengthiest blade has eyes on its ends. This blade is called main or master leaf, the remaining blades are called graduated leaves. All the blades are bound together by means of steel straps. The spring is mounted on the axle of the vehicle. The entire vehicle load rests on the leaf spring.The front end of the spring is connected to the frame with a simple pin joint, while the rear end of the spring is connected with a shackle. Shackle is the flexible link which connects between leaf spring rear eye and frame.When the vehicle comes across a projection on the road surface, the wheel moves up, leading to deflection of the spring. This changes the length between the spring eyes. If both the ends are fixed, the spring will not be able to accommodate this change of length. So, to
accommodate this change in length shackle is provided at one end, which gives a flexible connection. The front eye of the leaf spring is constrained in all the directions,where as rear eye is not constrained in X-direction. This rare eye is connected to the shackle.
Graduated leaves
Rebound clip
Central clamp
camber
Master leaf
Eye
Span 2L
During loading the spring deflects and moves in the direction perpendicular to the load applied. When the leaf spring deflects, the upper side of each leaf tips slides or rubs against the lower side of the leaf above it.This produces some damping which reduces spring vibrations, but since this available damping may change with time, it is preferred not to avail of the same.Moreover, it produces squeaking sound. Further if moisture is also present, such inter-leaf friction will cause fretting corrosion which decreases the fatigue strength of the spring, phosphate paint may reduce this problem fairly. The front end of the spring is connected to the frame with a simple pin joint, while the rear end of the spring is connected with a shackle as shown in figure.
A) Vehicle specification
The below figure is Tata LPS 4018 Tanker trailer. The trailer shown is heavy commercial vehicle with the capacity of 5675cc and with euro II emission norms.
The trolley on the truck has a tri axle arrangement at the back.
B) Problem Statement
Leaf springs are crucial suspension element used on light passengerrsquo;s vehicle necessary to minimize the vertical vibration impact and bump due to road
irregularities and to create a comfortable ride. The leaf spring is analyzed for static strength and deflection using finite element analysis. The general purpose leaf
spring design and finite element analysis software ANSYS is used for present study. The variations of stress and deflection values are predicted.
C) Objectives of the study
· To design leaf spring and axle of suspension system for TATA LPS 4018 tanker trailer.
· To calculate stress and deflection by applying various loads on the leaf spring.
· To model the leaf spring by using CATIA V5.
· To perform finite element analysis by using ANSYS 14.5 Workbench.
· To perform experimentation by using Universal testing machine (UTM).
D) Scope
The project begins with designing the leaf spring analytically. The use of software like CATIA V5 and ANSYS 14.5 has helped in modeling and static analysis of leaf spring by applying boundary conditions.Validation of the leaf spring model is done by using analytical, FEM and experimental methods.
E) Methodology
The methodology used in the project is as fo
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钢板弹簧是轻型和重型客车上必需的关键悬架元件，以减少由于路面不平而造成的垂直振动的影响和颠簸，创造一个舒适的乘坐环境。钢板弹簧广泛应用于汽车和铁路悬架。它通常是由一系列半椭圆形的平板组成。叶片是由两个U型螺栓和中心夹的方式固定在一起。回弹夹的主要功能是保持叶片对准和防止板块横向移位。最长的叶片称为主片，它的两端弯曲形成卷耳。弹簧的中心位置固定在车轴上。除了主片，多片式弹簧还有一个或两个额外的全长片。额外的全长片堆叠在主片和渐变长度叶片之间。额外的全长片用来提供横向剪切力。板簧应通过弹簧偏转的变化来吸收垂直振动和道路不平引起的冲击，使得势能作为应变能储存在弹簧中，并缓慢释放，从而增加板簧的储能能力，提供一个更舒适的悬架系统。
弹簧被定义为弹性元件，其功能是加载时发生变形，负载移除时恢复其原始形状。钢板弹簧通过弹簧偏转来吸收由于的道路不平顺引起的车辆振动、冲击和碰撞载荷，使得势能储存在板簧中，然后缓慢地释放。存储和吸收更多的应变能的能力保证了舒适的悬架系统。半椭圆形板簧普遍用于轻型和重型商用车的悬架。对于乘用车，则广泛应用于后悬挂。弹簧由许多叶片组成。叶片的长度是变化的。我们通常给叶片赋予初始曲率或弧度，使得它们在负载下趋于变直。板簧是基于具有均匀强度的梁的理论设计而成。最长的叶片在两端有卷耳。这个叶片就称为主片，其余叶片称为渐变叶片。所有的叶片通过钢带捆绑在一起。弹簧安装在车轴上。整个车辆的载荷靠板簧来承受。弹簧的前端通过简单的销接头连接到车架上，弹簧的后端用吊耳连接。吊耳是连接板簧后卷耳和车架之间的柔性连接件。当车辆遇到路面上的突起时，车轮向上移动，导致弹簧偏转。这就改变了弹簧卷耳之间的长度。如果两端是固定的，那么弹簧将不能适应这种长度的变化。所以，为了适应这种长度变化，只有一端有吊耳，这就是柔性连接。板簧的前卷耳所有方向上都被约束，而后卷耳在X方向上不受约束。
反弹夹
渐变刚度弹簧
中心夹
弧度
主片
卷耳
跨度 2L
在加载期间，弹簧偏转并在垂直于施加载荷的方向上移动。当钢板弹簧偏转时，每个叶片的上表面滑动或摩擦上方叶片的下表面。这就产生一些减弱弹簧振动的阻尼，但是由于这种可用的阻尼可能随着时间的推移而改变，最好不要使用相同的弹簧叶片。另外，还会产生吱吱的响声。如果有水，这种叶片间的摩擦将导致腐蚀，降低弹簧的疲劳强度，磷酸盐涂料则可以很好解决这个问题。弹簧的前端通过简单的销接头连接到车架，而弹簧的后端连接用如图所示的吊耳。
- 车辆规格
下图是塔塔LPS 4018油轮拖车。如图所示的拖车是容量为5675cc，具有欧II排放标准的重型商用车。卡车上的手推车在后面有一个三轴装置。
B）问题描述
板簧是轻型客车上使用的为了减小道路不平整引起的垂直振动冲击和碰撞的重要悬挂元件，它可以创造一个舒适的乘车环境。我们使用有限元来分析板簧的静态强度和挠度。本研究采用钢板弹簧设计和有限元分析软件ANSYS来预测应力和挠度值的变化。
C）学习目标
· 为塔塔 LPS 4018油轮拖车设计悬挂系统的板簧和车轴；
· 通过在板簧上施加各种载荷来计算应力和挠度；
· 使用CATIA V5对钢板弹簧进行建模；
· 使用ANSYS软件进行有限元分析；
· 使用万能试验机（UTM）进行实验。
D）范围
该项目从分析设计板簧开始。使用CATIA V5和ANSYS 14.5软件有助于通过应用边界条件对板簧进行建模和静态分析。板簧模型的验证通过使用有限元分析和实验方法来完成。
E）方法
该项目使用的方法如下：分析方法用于设计板簧，然后通过考虑板簧尺寸，使用CATIA V5进行建模。这个模型放在ANSYA 14.5工作台中，通过应用各种边界条件，完成有限元分析。使用万能试验机进行挠度和应力评价的实验工作。
悬架系统的分析
A）钢板弹簧的材料
钢板弹簧钢材料选择的基本要求是钢必须具有足够的硬度以确保尺寸要求，保证完全马氏体遍布整个叶片。通常，必须要有较高的合金含量，以确保当使用厚叶部分时具有足够的硬化能力。用于该实验的材料是55Si2Mn90。
板簧的材料通常是含碳量为0.90%~1.0%的普通碳钢。有关详细信息，请参阅印度标准“制造用于汽车悬架的涡旋，螺旋和层压弹簧的钢规格”。
许多行业用55Si2Mn90材料制造钢板弹簧。这些材料广泛用于抛物线板簧和常规多片式板簧的生产。板簧通过弹簧偏转吸收垂直振动，冲击和碰撞载荷，将势能储存在板簧中然后缓慢地释放。以下是该设计中板簧的设计参数：杨氏模量为200Gpa，泊松比为0.3，极限抗拉强度为1820〜2060Mpa，拉伸屈服强度为1680〜1920Mpa。布氏硬度值为534-601。所选材料的密度为7850kg/m3，材料的热膨胀系数为11times;10-6 /℃。
B）TATA LPS 4018的规格参数
制造商 Tata Motors
车辆 低温罐车拖车类
型号 油罐拖车，三轴
原动机 使用TATALPS4018拖拉机
拖车重量 59939.1N
有效载荷 235440N
拖车的总车辆重量 295379.1N
带有3轴的底盘 38259N
拖车总长 10.418米
拖车总宽度 2.495m
拖车总高度 1.270m
铁路线组合总长 14.015
横梁C段 125x65mm
轮距 6.260m
轴3号 150mmx150mm梁轴，16mm壁厚
板簧 75x13mm平：940mm卷耳中心-8
轮胎 10.00x20,16R，12nos
C）底盘车架的分析
- 主销轴上的负载分布：规格数据从TATA汽车获得。
·有效负载（Wp）= 235440 N
·拖车的总车辆重量（负载下）（Wg）= 295379.1 N
·油轮自重（Ws）= 59939.1N =（设计输入）
假定有效载荷和自重作用在油轮装载区域的中心。油轮的装载情况如下图所示
考虑在主销轴（RA）反应
（RK）RAtimes;6.260 =（WPtimes;4.175） （WStimes;4.175）
=（235440times;4.175） 59939.1times;4.175 RA = 196998.04
= 196998
RK = WP WS-RA
= 235440 59939.1-196998
= 98381.1
=每轴负载=（RA Wa）/ 3
=（196998 29430）/ 3 = 75476
每轴负载= 75476 N
主销施加载荷= 98381.1N
轴的承载能力为117720 N。施加的负载为75476N。因此，在允许的容量极限内,选择轴为12T.
- 油轮拖车轴上的负荷分布：
3）车轴计算：
·车轴总负载（Pa）= 196998 N
·车轴重量（Wa）= 29430
·三轴负载（3Pa）= Pa Wa
= 196998 29430 = 226428N
每个轴上的负载= 226428/3 = 75476 N
·最大 弯曲力矩（Mb）= 37738times;0.617 = 23284.346Nm
·轴材料屈服应力（sigma;ym）= 470MPa F.O.S = 2.5
·安全工作应力（S）= 470 / 2.5 = 188N / mm2 = 188times;1006N / m2
因此需要截面模量（Z）=（23284.346）divide;（188times;1006）= 1.238529times;10-04m3
圆轴截面模数梁（Z）= 282447.36mm 3 = 2.8244736times;10 -4 m 3
因此150 mmtimes;150 mm圆轴梁感应应力82.43times;1006 N / m2小于许用应力186.39times;1006 N / m2，操作安全。
d）板簧计算：
三轴负载（3Pa）= 226428N
车轴自重（Wa）= 29430N
板簧负载（P）= 226428-29430 = 196996N
每弹簧负载= 196998/6 = 32833N
该弹簧材料的屈服应力为= 1750N/mm2
安全系数= 2
安全工作应力（S）= 1750/2 N/mm2 = 875 N/mm 2
板簧尺寸：
眼对中心（L）= 0.940m
弹簧的宽度（b）= 0.075m
厚度（t）= 0.013m
工作应力（SWS）= 600 / mm2
负载（P）=（2xntimes;Stimes;btimes;t2）/（3times;L）
因此，弹簧数（n）=（32833times;3times;940）/（2times;600times;1006times;0.075times;0.03times;0.03）= 6.08
因此，所需叶的最小数量= 7
可用弹簧数（n）= 8
应力诱导（S）=（3times;32833times;0.940）/（2times;8times;0.075times;0.013times;0.013）= 456.5times;1006N/mm2
因此，八个弹簧的板簧对于操作是安全的。
e) 公式:
1）叶总数（n）
N = ne ng
2）有效长度：
2L = 2L1-1 ...（使用频带时）
2L = 2L1--1 ...（使用U型螺栓时）
3）最小叶的长度：
= 无效长度
主片
弧度
中心带
其余全长
渐变长度叶片
U型螺栓
第（n-1）叶片
弹簧卷耳
4）第（n-1）片叶的长度
= x（n-1） 无效长度
5）主叶长度
= 2L1 pi;（d t）times;2
6）板簧应力
7）板簧偏转
8）额外全长叶片的弯曲应力
9）刻度叶中的弯曲应力
10）
11）带有刻度叶的全长偏差
Y =
钢板弹簧设计：
设计输入：
轴承负载能力= 12T
= 12000kg
弹簧负载（2P）= 6000kg
一侧弹簧负载（P）= 3000kg
跨距（2L1）= 876mm
半跨距（L1）的长度= 438mm
无效长度（l）= 104mm
衣架长度（l1）= 150mm
叶片宽度（b）= 75
叶片厚度（t）= 13
弹簧的片数（ne ng = n）= 8
渐变弹簧片数数= 6
主片（ng）=1
额外全长叶数（ne）= 2
弹性模量
通过应用各种负载的分析结果：
下面示出的结果是考虑轴上的12T载荷分析计算的，并且3T载荷朝向弹簧分布。3T的负载挠度44.68mm，通过手算，应力为710.70times;106N/m2。在分析结果中获得的应力值小于安全工作应力。
应力（N/m2）
偏转（mm）
载荷（N）
序号
f）钢板弹簧计算结果:
轴
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