Structural Analysis of Ladder Chassis for Higher Strength - CiteSeerX

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1 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) Structural Analysis of Ladder Chassis for Higher Strength Abhishek Singh1, Vishal Soni2, Aditya Singh3 1 PG student, 2Assistant Prof., Dept. of Mechanical Engineering, Oriental Institute of Science & Technology, Bhopal-462021, India 3 UG student, Dept. of Mech. Engineering, Shri Ram College of Engg & Management, Gwalior-476444, India Abstract Automotive chassis is an important part of an Chassis of Automotive or automobile helps keep an automobile. It forms the bones of a vehicle. The chassis automobile rigid, stiff and unbending. Automobile serves as a frame work for supporting the body and chassis ensures less noise, vibrations and harshness different parts of the automobile, it should be rigid enough throughout the automobile. to withstand the shock, twist, vibration and other stresses & The different types of automobile chassis are as its principle function is to carry the maximum load for all designed operating condition safely. An important follows: consideration in chassis design is to have adequate bending A. Ladder Chassis: stiffness along with strength for better handling characteristics. Therefore, maximum shear stress and Ladder chassis is one of the oldest forms of deflection are important criteria for the chassis design. This automotive chassis these are still used in most of the paper describes Structural analysis & optimization of SUVs today. It is clear from its name that ladder chassis vehicle chassis with constraints of maximum shear stress resembles a shape of a ladder having two longitudinal and deflection of chassis under maximum load. In the rails inter linked by lateral and cross braces. present work, we have taken higher strength as the main issue, so the dimensions of an existing vehicle chassis of a TATA LP 912 Diesel BS4 bus is taken for analysis with materials namely Steel alloy (Austenitic) subjected to the same load. The four different vehicle chassis have been modeled by considering four different cross-sections. Namely C, I, Rectangular Box (Hollow) and Rectangular Box (Intermediate) type cross sections. For validation the design is done by applying the vertical loads acting on the horizontal different cross sections. Software used in this work Pro e 4.0 & Altair Hyperworks 11.0.0.39 (Hypermesh). Keywords Vehicle chassis, Static analysis, Steel alloy (Austenitic), C, I, Rectangular Box (Hollow) and Rectangular Box (Intermediate) type cross sections. Fig 1: Model of C cross section type of ladder chassis I. INTRODUCTION B. Monocoque Chassis: Automotive chassis is a frame just like skeletal on Monocoque Chassis is a one-piece structure it is which various machine parts like engine, tires, axle overall shape of a vehicle. Such type of automotive assemblies, brakes, steering etc. are bolted. It gives chassis is manufactured by welding floor pan and other strength and stability to the vehicle under different pieces together. Therefore monocoque chassis is cost conditions. Frames provide strength as well as flexibility effective and suitable for robotized production, now a to the automobile. Automotive chassis is the supporting day most of the vehicles make use of steel plated frame like backbone of any automobile to which the body monocoque chassis. of an engine, axle assemblies are affixed. Tie bars, which are essential parts of frames, are fasteners that bind C. Backbone Chassis: different automotive parts together. Automotive frames In Backbone chassis it has a rectangular tube type are generally manufactured from steel alloys. Frame backbone, which is usually made up of glass fiber that is holds the body and motor of an automotive vehicle. used for joining front and rear axle together. This type of According to the structure of chassis, the body of a automotive chassis or automobile chassis is strong and vehicle is flexibly molded at the time of manufacturing. powerful enough to provide support it is used in smaller Automobile chassis is generally made of light sheet sports car. Backbone chassis is easy to manufacture and metal. It provides strength needed for supporting also cost effective. vehicular components and payload placed over it. 253

2 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) II. LITERATURE REVIEW 112 kg as compared to case 1, 2 and 3. So that the Roslan Abd Rahman: does stress analysis on heavy modifications as per case 4 are also recommended, case 3 duty truck chassis by finite element package ABAQUS. the weight reduction is 88 kg with maximum stress level To improve the fatigue life of components at critical in range of 25MPa to 66 MPa. point by design modifications the stresses can be reduces. He uses ASTM low alloy steel a 710 C (Class 3) with III. PROBLEM STATEMENT 552 MPa of yield strength and 620 MPa of tensile In present the Ladder chassis which are uses for strength for chassis founds the maximum stress 386.9 making buses and trucks are C and I cross section type, MPa at critical point occurred at opening of chassis. This which are made of Steel alloy (Austenitic). In India no of critical point is located at element 86104 and node 16045, passengers travel in the bus is not uniform, excess which was in contacted with the bolt from it he passengers are travelling in the buses daily due to which concludes, that this critical point is an initial to probable there are always possibilities of being failure/fracture in failure. the chassis/frame. Therefore Chassis with high strength Cicek Karaoglu: does stress analysis of heavy duty cross section is needed to minimize the failures including truck chassis with riveted joints by using a finite element factor of safety in design. Basically C cross section type package ANSYS version 5.3. He examine the effect of of chassis is used in buses and I cross section type in the side member thickness and connection plate thickness heavy trucks where high strength is required. So we have with length change, the thickness of the side member is taken Rectangular Box type cross section for making varied from 8 to 12 mm, and the thickness of the ladder chassis by fabricating it which is used in small connection plate is also varied by local plate from 8 to 12 trucks. It will give best strength among all above three. mm, the connection plate thickness is varied from 7 to 10 Another type of cross section we have taken is also mm, and the length of the connection plate (L) is varied rectangular box type section but it is filled diagonally so from 390 to 430 mm during his study. From it he that this type of intermediate structure can increase the concluded that if it is not possible to change the side strength of chassis. member thickness using local plates, because of increase The problem to be dealt with for this dissertation in weight of chassis then choosing an optimum work is to Design and Analyses using suitable CAE connection plate length (L) seems to be best practical software for ladder chassis. solutions for decreasing the stress values. Mohd Azizi Muhammad Nor: determine the stress IV. OBJECTIVES analysis of an actual low loader structure having I-beams The aim of this work is to achieve good strength design application of 35 ton trailer. He uses CATIA of automotive ladder chassis, so engineering solution to V5R18 for modeling. Analysis results show that the the component addressing functionality during the location of maximum deflection and maximum stress service life of the component. The component should agrees with theoretical maximum location of simple withstand all the forces acting on it without rupture or beam under uniform loading distribution. This shows that failure or undue deformation that might render the there is discrepancy between the theoretical (2-D) and component incapable during its service life because of a numerical (3-D FEA) results. It shows that the maximum mishap due to sudden failure during operation. deflection is pointed in situated in between BC1 and BC2 An attempt to evolve an improved design resisting the with magnitude of 7.79mm. The results show the failure and in turn enhancing the life would be the numerical analysis revealed that the location of objective for this dissertation work. The key objectives maximum deflection and maximum stress agrees well for this work: with theoretical maximum location of simple beam 1) Identify and study using software tools (for loaded by uniform force. simulation/ analysis), the nature and N.K. Ingole: make the modifications in existing model characteristics of stresses acting on the of tractor trailer chassis by 1) Variation in cross members component. in there Cross sectional areas, 2) Variation in cross and 2) Evaluate the influence of the loads/ mass/ longitudinal members in there cross sectional areas, 3) geometry/ boundary conditions over the nature and Variation in cross and longitudinal members in there extend of stresses. cross sectional areas and 4) Changing the position of 3) Review the existing design and consider cross members of main frames of chassis, Considering improvement for negating the harmful influences variable cross sectional areas of cross and longitudinal of undue stresses. members. It was found that, maximum stress present in existing chassis was 75 MPa and weight of chassis was 751.82 kg. Case 4 leads to reduction in weight of approx. 254

3 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) V. METHODOLOGY A finite element stress analysis need to be carried out at the failure region to determine the stress distribution and possible design improvement. Since suitable software like ProE, Catia, Solid Works, Unigraphics, etc. are normally utilized for creating the geometry of the component (3D model). The design verification can be achieved without elaborate need for prototypes at each phase saving time and effort. A final prototype for the final design review can be employed for verifying the analytical results. Specification of Ladder chassis: Fig 2: CAD Model of C cross section type of ladder chassis Wheel Base (WB) = 4920 mm Rear Overhang (ROH) = 2700 mm Front Overhang (FOH) = 1275/1430 mm Gross Vehicle Weight (GVW) = 9000 kg = 9 ton Length = 8897 mm Width = 2200 mm Specification of Material (Steel alloy -Austenitic): Mass density = 7.86 g/cm3 Yield strength = 207 MPa Ultimate Tensile Strength = 345 MPa Youngs Modulus = 220 GPa Poissons ratio = 0.275 Fig 3: CAD Model of I cross section type of ladder chassis Shear Modulus = 86.2745 Gpa Basic Calculation for Chassis: Weight of passengers = Weight per passenger No. of passengers = 75kg 51 = 3825 kg = 3.825 ton Total load acting on chassis = Gross vehicle weight + Weight of passengers = 9000 kg + 3825 kg = 12825 kg = 9 ton + 3.825 ton = 12.825 ton Chassis has two longitudinal members so load will be Fig 4: CAD Model of Rectangular Box (Hollow) cross section type acted upon these two longitudinal members. Therefore, of ladder chassis load acting on each member will be half of the total load acting on chassis. Load acting on one longitudinal member = 12.825 ton 2 = 6.288 ton Fig 5: CAD Model of Rectangular Box (Intermediate) cross section type of ladder chassis 255

4 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) A). Analytical Method: The analytical/ computational approach offers results through simulation/ analyses for the case study predefined for the solver. The technique would deploy any of the following software tools: Ansys, Hyper mesh, Nastran, Abaqus, Radioss or any compatible CAE software in the `Structural domain. Fig 10: Mesh quality check on C cross section type of ladder chassis Fig 6: Mesh on C cross section type of ladder chassis Fig 11: Mesh quality check on I cross section type of ladder chassis Fig 7: Mesh on I cross section type of ladder chassis Fig 12: Mesh quality check on Rectangular Box cross section type of ladder chassis Fig 8: Mesh on Rectangular Box cross section type of ladder chassis Fig 13: Mesh quality check on Rectangular intermediate cross section type of ladder chassis Fig 9: Mesh on Rectangular intermediate cross section type of ladder chassis 256

5 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) B). FEA for ladder chassis: Now a days in industry shorter product development cycle and faster time-to-market is done, with increased emphasis on up-front analysis to design, develop, and optimize a reliable and durable product. Electronic prototyping, reduce development costs instead of hardware prototyping. Today structural analysis is to perform system analysis instead of component analysis. The advent of faster computers and robust FEA software allows Design engineers to build larger, more refined and Fig 16: Max Shear stress on C cross section type of ladder complex models resulting in timely, cost-effective, chassis accurate, and informative solutions to customer I- CROSS SECTION TYPE: problems. The effects of stress, strain and displacement are computed in the structural analysis under the varying load condition. C). Structural analysis of Ladder Chassis: C- CROSS SECTION TYPE: Fig 17: Displacement on I cross section type of ladder chassis Fig 14: Displacement on C cross section type of ladder chassis Fig 18: Von Mises stress on I cross section type of ladder chassis Fig 15: Von Mises stress on C cross section type of ladder chassis Fig 19: Max Shear stress on I cross section type of ladder chassis 257

6 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) Rectangular Box (HOLLOW) Cross Section Type: Fig 24: Von Mises stress on Rectangular Box (Intermediate) cross section type of ladder chassis Fig 20: Displacement on Rectangular Box (Hollow) cross section type of ladder chassis Fig 25: Max Shear stress on Rectangular Box (Intermediate) cross section type of ladder chassis Fig 21: Von Mises stress on Rectangular Box (Hollow) cross section type of ladder chassis In the analysis of existing component, we have taken quad element of 3mm size for meshing. Element size is taken in such a way every geometry feature should be captured in mesh. If there is any hole then washer is provided on it to get adequate result. More the number of elements accuracy will increase but solution time will also increase so a proper combination between accuracy and solution time is considered while choosing the element size. VI. RESULT After the calculation carried on Hyper Mesh we have Fig 22: Max Shear stress on Rectangular Box (Hollow) cross section type of ladder chassis concluded that our Rectangular Box (intermediate) section is safer under 12.825 tone load which is the Total Rectangular Box (INTERMEDIATE) Cross Section Type: weight of vehicle including gross vehicle weight and weight of passengers. The displacement is good of our Rectangular Box (intermediate) section in comparison to C, I and Rectangular Box (hollow) section type chassis therefor our chassis is more safer among all type of cross sections. Fig 23: Displacement on Rectangular Box (Intermediate) cross section type of ladder chassis 258

7 International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 2, February 2014) TABLE I REFERENCES COMPERATIVE ANALYSIS OF DIFFERENT CHASSIS [1] Yucheng Liu, Crashworthiness Analysis of Finite Element Truck Chassis Model Using LS-DYNA, 11th International LS-DYNA S. Cross- Displacem VonMise Max. Shear Users Conference, Department of Mechanical Engineering, University of Louisiana, Lafayette, LA 70504, USA. No sections ent s Stress Stress (mm) (Mpa) (Mpa) [2] Vijaykumar V. Patel, R. I. Patel, Structural analysis of a ladder chassis frame, World Journal of Science and Technology 2012, 2(4):05-08, ISSN: 2231 2587. 1 C-Type 6.153 3.01102 1.59102 [3] Hemant B.Patil, Sharad D.Kachave, Eknath R.Deore, Stress Analysis of Automotive Chassis with Various Thicknesses, IOSR Journal of Mechanical and Civil Engineering (IOSR- 2 I-Type 4.786 2.34102 1.24102 JMCE), Vol. 6, Issue 1 (Mar. - Apr. 2013), PP 44-49. [4] N.V.Dhandapani, Dr. G Mohan kumar, Dr K.K.Debnath, Static Analysis of Off-High Way Vechile Chassis supporting Structure for the effect of various Stress dstributions, IJART, Vol.2 Issue 3 Rectangular 2.683 1.27102 6.53101 1, 2012, 1-8. Box (Hollow) [5] Haval Kamal Asker, Thaker Salih Dawood, Arkan Fawzi Said, Type Stress Analysis os standard Truck Chassis during ramping on Block using Finite Element Method, ARPN Journal of Engineering and Applied Sciences, Vol. 7, NO. 6, June 2012 4 Rectangular 1.839 1.12102 5.81101 [6] M. Ravi Chandra, S. Sreenivasulu, Syed Altaf Hussain, Modelling and Structural Analysis of Heavy Vehicle Chassis Box made of Polymeric Composite Material by three different Cross (Intermediate) Sections, Journal of Mechanical and Production Engineering Type Research and Development (IJMPERD ) ISSN 2249-6890 Vol.2, Issue 2, Sep 2012, 45-60. [7] Monika S. Agrawal, Md. Razik, A Review on Study of VII. CONCLUSION Analysis of Chassis, International Journal of Modern From the results, it is observed that the Rectangular Engineering Research (IJMER), Vol.3, Issue.2, March- April. 2013, pp-1135-113. Box (Intermediate) section is more strength full than the [8] Roslan Abd Rahman, Mohd Nasir Tamin, Ojo Kurdi Stress conventional steel alloy chassis with C, I and Rectangular analysis of heavy duty truck chassis as a preliminary data for its Box (Hollow) section design specifications. The fatigue life prediction using FEM Jurnal Mekanikal December Rectangular Box (Intermediate) section is having least 2008, No. 26, 76 85. deflection i.e., 1.839 mm in all the four type of chassis of [9] Cicek Karaoglu, N. Sefa Kuralay Stress analysis of a truck different cross section. Finite element analysis is chassis with riveted joints Elsevier Science B.V Finite Elements in Analysis and Design 38 (2002) 11151130. effectively utilized for addressing the conceptualization [10] Mohd Azizi Muhammad Nora,, Helmi Rashida, Wan Mohd Faizul and formulation for the design stages. The results Wan Mahyuddin Stress Analysis of a Low Loader Chassis obtained are quite favorable which was expected. The Elsevier Ltd. Sci Verse Science Direct Procedia Engineering 41 iterations are carried out in the analysis phase which ( 2012 ) 995 1001. yields the suitable values for design parameter. [11] N.K.Ingole, D.V. Bhope Stress analysis of tractor trailer chassis Following information is achieved. for self-weight reduction International Journal of Engineering Science and Technology (IJEST), ISSN: 0975-5462 Vol. 3 No. 9 1) Part is safe under the given loading condition. September 2011. 2) To improve performance, geometry has been modified which enables to reduce stress levels marginally well below yield limit. 259

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