International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 7 Design and Front Impact Analysis of Rollcage Gautam Yadav and Ankit Jain Abstract--- Mechanical design, as classically taught in engineering centered on the on the application of stress analysis theory. While this theory is important, actual industrial design is generally dependent upon manufacturing, time constraints, and cost constraints as well as stress analysis. The goal of project is to design & Analyze a prototype of single seated off road all terrain rugged vehicles that withstand rigours of a rough terrain in all types of weather without damage. The objective is for a team of students to design and analysis an off-road vehicle powered by an eleven horsepower Lombardini petrol engine. The vehicle must be safe, easily transported, easily maintained and fun to drive. It should be able to negotiate rough terrain without damage. Thus the chassis design becomes very important. Typical capabilities on basis of which these vehicles are judged are hill climbing, pulling, acceleration & maneuverability on land. The vehicle is required to have a combination frame and roll cage consisting of steel members. The purpose of the roll cage is to provide a minimal three-dimensional space surrounding the driver. The cage must be designed and fabricated to prevent any failure of the cages integrity. As weight is critical in a vehicle powered by a small engine, a balance the use of solid modeling and finite element analysis (FEA) software is extremely useful in addition to conventional analysis. The following paper outlines the design and analysis of the Mini Baja Vehicle s frame design. It will cover the design constraints required by SAE, material selection, initial design, and structural analysis. It will finally cover the results of the actual real world usage of the frame design [1] Keywords--- Design, Analysis, Driver Safety T I. INTRODUCTION HE definition of a roll-cage is a a structural frame work designed to prevent serious body shell deformation in the case of a collision or roll-over. But a roll cage is better described as a Rollover Protection Structure (or system). The basic purpose of the roll cage is to protect the occupant in case of a roll over or a collision. It must be able to understand the weight of the car landing on the proof providing protection to riders of such vehicles from road hazard, debris and the element. It comprises a framework of a circular or hollow steel tubing welded together to form a cage having a front portion and overhead protection over which a weather proof fabric cover having at least a front mounted window is place able to form an enclosed cab. The framework is easily attachable to the existing front and rear structures of an all-terrain vehicle so as to cover and enclose the rider s area. The frame work is use able with or without the cover for roll over protection and also provides a means to deflect branches and similar hazards away from the rider by virtue of the design of the front portion [1]. II. ROLLCAGE DESIGN The main function of the roll-cage is to protect the driver and support all control system like suspension, steering, engine and driver. The design factor contains durability and maintenance of the frame. The roll cage must be design under the rule of BAJA SAE. The pipe use for the roll-cage fabrication is 1018 steel. The diameter of the pipe is 1 (inch) and thickness is 0.10 (inch). They will be welded together using MIG Welding. The CAD Model is being designed using Solid-Works STUDENT Edition software. We have used PVC pipes to construct a reference model of roll-cage. Gautam Yadav, BE- Mechanical Engineering, Jawaharlal Institute of Technology, Borawan (Khargone) Madhya Pradesh 4518 Ankit Ja M-Tech, Thermal Engineering, Sri Satya Sai Institute of Science & Technology, Sehore, (M.P) PAPER MED13
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 73 Figure 1: The Bend or Curve provide in the SIM to give More Space for the Driver to have High Comfort level.[1][] III. CONFORMANCE PARAMETERS Sl. No. Parameter Rule-Book Value Actual Value 1 Max Length 108 inches 89.01 inches Max Width 64 inches 60 inches 3 Height 41 inch or more 48.5 inches 4 Pipe OD 1 inches 1 inches 5 Thickness 0.1 inches 0.1 inches 6 Material 1018 steel 1018 steel 7 SIM height from Driver Seat Between 8 to 1 inches 10 inches 9 RRH width 7 above driver sheet 9 inches 31.55 inches 10 Height above driver helmet 6 inches 10 inches 11 RRH max can be 4 member member 1 Angle between FBM & start of C bend 45 45 13 Max length of any member 40 inches Less than that 14 Max length any un supported bend 3 inches 30 inches of FBM 15 Driver should be away from roll cage envelop 3 inches 4 inches IV. K.E. = 0.5(m 1 +m ) v FORCE FOR IMPACT Substituting v from above and subtracting, the loss of kinetic energy of system is given by
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 74 KE = 0.5 m 1 (v 1 -v ) [(m 1 m ) +1] In case the two vehicles of approx. same mass collide with one at rest KE = 0.5m 1 v 1 Now we know that F * v = power = KE/t Where t = time of impact, in the most of the crashes it is of order of 100ms F= force associated with the impact m = mass of vehicle=71 Kg (including driver)[4] 4.1. Different Lode Points Are Shown In Fig Mesh Type: Mesher Used: Element Size: Quality: Figure : Front impact Analysis Table 1: Mesh Information Beam Mesh Standard mesh 1.9541 in High Number of elements: 993 Number of nodes: 1384 V. STATIC ANALYSIS OF ROLL CAGE We have done static analysis for Front impact test [5]. Elements 3D Elastic Beam Elements (Beam5) Line Elements 6 DOF Material Properties Linear, Elastic, Isotropic (steel 1018) Exy = 05 GPa
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 75 Poisson s Ratio = 0.9 Element Properties CROSSSECTIONAL AREA =.143E-5 m IZZ = 1.3615E-8 IYY = 1.3615E-8 TKZ = 1 TKY = 1 Front Impact test 5.1. Force Estimation for Loading Conditions Let m 1, v 1 and m, v be the mass and velocity of two bodies respectively before the impact and let v be the common velocity of the cg at the instant of impact. Then, v = (m 1 v 1 +m v ) (m 1 +m ) Before impact the total kinetic energy of system was, K.E.1= 0.5(m 1 v 1 + m v ) At the instant the two C.G. are moving with same velocity, the kinetic energy is K.E. = 0.5(m 1 +m ) v Substituting v from above and subtracting, the loss of kinetic energy of system is given by KE = 0.5 m 1 (v 1 -v ) [(m 1 m ) +1] In case the two vehicles of approx. same mass collide with one at rest KE = 0.5m 1 v 1 Now we know that F * v = power = KE/t Where t = time of impact, in the most of the crashes it is of order of 100ms F= force associated with the impact m = mass of vehicle=71 Kg (including driver) Substituting the respective value in above equation we get For design purpose we consider impact force of 9500 N Rear Corner Points All D.O.F. =0 5.. Study Results for Front Impact The maximum stress in a beam is the sum of bending and direct stresses. For a round beam, the following formula can be used: σ max = σ dir + (σ by + σ bz ) 1/ This value can be computed in Solid-Works, at node for each element[5]. Table : Default Results Name Type Min Location Max Location Stress1 TXY: Shear in Y Dir. on YZ Plane 0 N/m^ Element: 317 (9 9 1.87591e+008 N/m^ Element: 333 (8.99359-0.00789447
International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 76-8 in) -3.87949 in) Displacement1 URES: Resultant Displacement 0 mm Node: 135 (9.03966.965-7.89 in).463 mm Node: 545 (0.0608674 6.9471 59.993 in) Figure 3: Front Impact Test-Displacement Maximum stress obtained= 1.87591e+008 N/m^ Now F.O.S. = Yield stress/max stress = 365000000/187591000 = 1.9 Figure 4: Front Impact Test-Factor of Safety VI. CONCLUSION The cage is particularly design for the automobile, for rough road drive. This design is beneficial for un-even road as in urban areas and in undeveloped areas. This design will be positively affect to the transportation and luxurious drives in all areas. This design will give a satisfactory driving condition and thus by some modification will play a great deal in automobiles industry. REFERENCES [1] www.bajasaeindia.org/rulebook (Design Specification) [] Bhandari VB, Design of Machine Element ; PHI Learning [3] Norton R; Design of Machinery; TMH [4] Juvinall RC, Marshek KM; Fundamental of Machine Component Design; Wiley [5] Solidworks 010 Student Edition Software (For modeling and analysis)