Investigation On Smart Materials For Light Duty Goods Vehicle Chassis Frame Using Fea

Weight directly affects performance and emission parameters of vehicle. The main contributor of weight in heavy vehicle is chassis frame [1]. The reduction of weight of chassis improves fuel economy and reduces carbon dioxide emission. There are several conventional and non-conventional chassis materials available in the market [2]. Composite materials future looks promising because of their lesser weight and higher performance [3]. Proper usage of such product will help in fuel economy thus, saving the fuel and environment [4]. Also it helps to achieve higher performance readily than other conventional materials [5]. Hence, in this Project, we are going to reduce the weight of TATA ACE chassis using composites after the design and analysis of chassis frame [6]. Different materials are tested in ANSYS software are the material having the best desirable properties is recommended for further application in the automotive industry [7].


Introduction
x Chassis is a French term which is used to denote complete body and structure of the vehicle.
x It contains all the major units necessary to propel the vehicle direct its motion, stop it and allow it to run smoothly over uneven surfaces. x The chassis is the major weight constituting part of automobile.
x The chassis constitutes about 20% of the automobile weight.

FUNCTIONS OF THE CHASSIS FRAME
1. To carry load of the passengers or goods carried in the body. 2. To support the load of the body, engine, gear box etc. 3. To withstand the forces caused due to the sudden braking or acceleration. 4. To withstand the stresses caused due to the bad road condition. 5. To withstand centrifugal force while cornering.

Conventional Frame
It is non-load carrying frame. The loads of the vehicle are transferred to the suspensions by the frame. This suspension in the main skeleton of the vehicle is supported on the axles through springs. The body is made of flexible material like wood and isolated frame by inserting rubber mountings in between. The frame is made of channel section or tubular section or box section.

Integral Frame
This frame is used now a day in most of the cars. There is no frame and all the assembly units are attached to the body. All the functions of the frame carried out by the body itself. Due to elimination of long frame it is cheaper and due to less weight most economical also. Only disadvantage is that the repairing is difficult.

Semi-Integral Frame
In some vehicles half frame is fixed in the front end on which engine gear box and front suspension is mounted. It has the advantage when the vehicle is met with accident the front frame can be taken easily to replace the damaged chassis frame. This type of frame is used in some of the European and American cars. The frames are made of following sections. Box section is used in short members of the frame. Channel section is used in long members of the frame. Tubular section is used these days in three-wheelers, scooters and matadors, pick-ups frames.
Channel section is good for bending, tubular in torsion and box in bending and torsion.

IMPORTANT FACTORS TO CONSIDER
The material chosen should have lesser weight than previously used material for mini truck frame without compromising strength. The chassis should be able to withstand various acting forces in the frame. The newly designed chassis should be safe, efficient and economical.

SELECTION OF MATERIALS
The materials are selected by considering density, strength, cost and availability parameters. By studying the various properties of materials these materials are selected for Analysis. They are as follows.

Steel
Aluminum epoxy Aluminum propylene 6.1 Steel Steel is existing chassis material of TATA Ace chassis so analysis is done on the reference of steel regarding their weight, cost and strength properties. Carbon composites and its growing use is one of the driving factor for analyzing. Carbon composites are having higher strength as well as good fatigue resistant properties. Aluminum epoxy is having very long pot life (working time) as well as less brittle in nature. The combined weight of aluminum along with the epoxy is lesser in comparison with the other composites.Aluminium propylene is already used in a new material called injector. It has already promised that this material can reduce the weight of chassis by 50% and enhance the performance of automotive vehicle.

Aluminum Epoxy
Aluminum/polymer composites are attractive materials for a wide range of industrial applications due to the combination of properties such as low density, corrosion resistance, thermal stability, and ease of fabrication. Aluminum/epoxy composites are fabricated by cast molding method using 10 wt. % unmodified and salinized aluminum powders. They are having excellent adhesive properties. Cost of epoxy is three times less than same weight of carbon fiber. Epoxy tends to be stronger than other resins and is less brittle in nature. Density of epoxy is same as polyester resin but viscosity is higher than other resins. They are much stronger in adhesion. They tend to have greater working life.  Figure 5. Chemical representation of epoxy

Aluminum Propylene
Aluminum propylene is recently used as automotive material. Infector has developed a patented lightweight technology which uses aluminum skin bonded with an expanded propylene (EPP) core. Infector can reduce weight from 300kg typical for chassis to 160kg. To add to its advantage, the sandwiched material is 100% recyclable. It is lesser in weight but comparative stronger than other material counterparts.   For applying composite over the chassis section we are going to modify the design structure of chassis having rectangular box frame instead of C channel frame.

DESIGN OF CHASSIS FRAME
After calculation of chassis frame, the sample chassis of TATA ACE mini truck frame is designed using SolidWorks software. The design procedure was based on creating a model, viewing it, assembling parts as required, and then generating any drawings which are required. The original chassis of Tata Ace is designed for structural analysis of steel frame. For Analyzing composite section, the chassis design is modified. Instead of original C-channel section ladder frame, rectangular box section type ladder chassis is designed. The dimensions of both side bars and cross bars of modified sections are kept same.

Analysis of Chassis Frame:
After designing the chassis frame, the frame is subjected to the analysis. The analysis is done in ANSYS software. CAD model of TATA is created and imported into ANSYS for FEA. The design created by SolidWorks is used in ANSYS for structural analysis. The C channel section which is the conventional chassis is used to analyze structural steel. The second modified design is used to analyze Aluminum epoxy and Aluminum propylene respectively. The size of elements is kept as minimum as possible to get the accurate results and at some points the finer meshing is also done to get better results. Static analysis is used to find maximum stress region. After analysis, the obtained results are used to conclude the best material.
The designed model from of chassis using SolidWorks is saved in IGES format which can be directly imported into ANSYS workbench.

Load Applications and Boundary Conditions
Load in Tata Ace chassis is applied in two different chassis design in the form of pressure. Pressure of magnitude 0.017834 MPa is applied in Original C-Cross section chassis whereas 0.0105853MPa is applied in modified rectangular Cross section chassis. There are two boundary conditions which includes fixing the front and the rear axle.

CONCLUSION
The design and Tata Ace chassis using C-section and rectangular cross section is done in SolidWorks and imported to ANSYS for finite element analysis. The analysis is conducted in conventional steel, Aluminum Epoxy and Aluminum Polypropylene respectively. After analysis a comparison is made between existing conventional steel chassis and composite materials in terms of deformation and stresses, to select the best one. From the calculations, it is found out that Aluminum Propylene has the lowest weight compared to steel and aluminum epoxy. Also, Aluminum Polypropylene has the lowest equivalent stress, principal stress, shear stress and lowest deformation induced. Based on the results it was inferred that Aluminum Polypropylene composites with rectangular box section has superior strength to withstand high load and induced low deformation and stress distribution when compared to steel.