Life Determination by Fatigue Analysis and Modal of Intermediate Steering Shaft and Its Optimization

Transcription

1 IJSTE - International Journal of Science Technology & Engineering Volume 2 Issue 1 July 2015 ISSN (online): X Life Determination by Fatigue Analysis and Modal of Intermediate Steering Shaft and Its Optimization Nitin S. Duryodhan Department of Mechanical Engineering S.S.P.A.C.E., Wardha, India Dr. R. R. Gawande Department of Mechanical Engineering B.D.C.E. Sevagram, Wardha, India Prof. U. D. Gulhane Department of Mechanical Engineering B.D.C.E. Sevagram, Wardha, India Abstract The Optimization in the automobile technology reduces lots of human efforts to drive a four wheeler vehicle. The Software results, mathematical and logical calculation implementation in a research will increase the performance and efficiency of a design that may be use to get an optimized output from the system. Here in this paper optimization of the intermediate steering shaft can be done by making the dimensional changes to the intermediate steering shaft with the help of the software Creo and Ansys. In Ansys the modelled shaft is imported and structural, modal and harmonic analysis are done on existing and all the dimensionally changed intermediate steering shafts for the optimization.fatigue analysis of intermediate steering shaft is done to find the life of the intermediate steering shaft in cycles of both existing and the optimized and determined the life of the intermediate steering shaft in kms/hr.. Keywords: Intermediate: steering shaft: fatigue: modelling: analysis and optimization I. INTRODUCTION Automobile Intermediate steering shaft is the main media to guide the vehicle in the required direction.. In creo modelling of the intermediate steering shaft is done and further various types of dimensional changes are made for the optimization. The most conventional steering arrangement is to turn the front wheels using a hand operated steering wheel which is positioned in front of the driver, via the steering column, which may contain universal joints which may also be part of the collapsible steering column design, to allow it to deviate somewhat from a straight line which consist of the intermediate steering shaft. So it is the main part of the steering system. Analysis such as structural is done to calculate deformation in the shaft and YZ shear stress for the stress calculation in Z direction and the von mises stress which is used for determining the safe stress condition of both existing and optimized. Modal analysis shows frequency i.e. Harmonic frequency and the modes of frequency at which frequency what happens it done for both existing and optimized. Harmonic analysis which shows the graph while engine running conditions for both existing and optimized. II. LITERATURE REVIEW 1) Kenneth L. Oblizajek and John D. Sopoci "Small Amplitude Torsional Steering Column Dynamics on Smooth Roads: In- Vehicle Effects and Internal Sources" SAE International Published 04/12/2011. The paper describes the onroad effects of these conditions at typical highway speeds, a laboratory test procedure for evaluation of the column contributions, and the source for the dynamic amplification within the column. In this Internally excited torsional steering wheel vibrations are at frequencies near 8-22 Hz on smooth roads can produce driver disturbances. This disturbance is responsive to periodic excitation of the rotating corner components, the frequency of which is directly proportional to the speed of the vehicle. The disturbance becomes observable as a tactile sensation with repetitive pulsations sensed in the pads of the fingers or in the hands on the steering wheel. 2) B.Babu, M. Prabhu, P.Dharmaraj, R.Sampath "Stress Analysis On Steering Knuckle Of The Automobile Steering System" IJRET Volume: 03 Issue: 03 Mar This Paper is about the steering Knuckle which is modeled using CAD software and various parameters such as Nodal displacements, Stress distribution are completely analyzed and studied. The study shows that the areas where the stress concentration is maximum due to the applied load and the portions in order to avoid frequent failures to improve its reliability. And shows how the stress calculations and deformation calculations are done. All rights reserved by 218

2 3) K. Lohith Dr. S.R. Shankapal,M.H Monish Gowda Development of four wheel steering system for a car Volume: 12 Issue: 01 April In this project Maruti Suzuki 800 is considered as a benchmark vehicle. In This Paper development of steering system is done by making changes in the design of steering which consists of two bevel gears and intermediate shaft which transmit 100% torque. The prototype was tested for its cornering ability through constant radius test and was found 50% reduction in turning radius and the vehicle was operated at low speed of 10 kmph. 4) Bhushan Akhare and Sanjeev S. Chouhan Performance and Value analysis of Power steering system IJETAE Volume: 2 Issue: 08 August Here in this paper all those points are discuss that will help to understand the whole system and the efforts that can be increase the efficiency of the power steering system. The power steering system mainly contains a steering wheel that wheel is connected with the shaft this shaft is then connect with the electronics system this system works according to position and torque sensor activity, this output will used to turn the vehicle in a preferred direction using a dc motor. Power steering made vehicle driver smooth and effective driving in this paper the part of automobile i.e. steering is consider and how it works in terms of performance and values. 5) D. Toffin G. Reymond, A Kemney, J. Droulez: Influence of Steering Wheel Torque Feedback in a dynamic driving Simulator. From this paper the torque on the steering wheel is estimated that it has of 2.5 Nm sense by electronic force feedback configured system. A preliminary study on the role of torque feedback in the steering wheel was conducted on the Clio dynamic driving simulator at RENAULT. An experiment comparing different torque feedback strategies was conducted to evaluate the potential of driving simulators in the study of future steer-by-wire system. 6) Dan Xiang, Jian-zhong Yuan, Wei Xu: "Study on Fuzzy PID Algorithm for a New Active Front Steering System "JCET Vol.2 No.1 January 2012 PP The development of modern vehicle steering system has experienced five stages the mechanical steering system, hydraulic steering system, electro hydraulic power steering, system electric power steering system and active steering system. So far as safety and steering feelings are concerned, active front steering is a main trend of the development of current steering system has been discussed in this paper. 7) Rinse Winse Dhanesh Chatta and Ashish Nair Dept. of Mechanical Engineering, Govt. College of Engineering Kannur, Kannur, Kerala. Design of Pneumatic Collapsible Steering (IJTARME) Volume-2, Issue-2, In this Paper pneumatic collapsible steering column study is done which consist of single long collapsible steel rod which connects steering wheel to the steering box. The main advantages of pneumatic steering are that provides working space for proper functioning of air bag. Its maintenance cost is low since need only to replace air or gas in it. III. PROBLEM DEFINITION 1) Steering 1. The intermediate steering shaft is subjected to the continuous twisting loading and hence there is wearing at the connected surfaces due to this after some no. of Kms the shaft have to be changed. 2) Due to vibrations while engine running conditions the shafts gets wear and due this continuous deformation takes place so the intermediate shaft has to be changed. 3) Clattering noise comes from the steering system when there is wear in the shaft. IV. MODAL ANALYSIS Use modal analysis to determine the vibration characteristics. The solution of vibration analysis is divided into five sets of vibration. It is also called as modes of vibration. Vibrations set up in intermediate steering shaft are described in the form of frequency. Each set of frequency gives maximum deformation in that mode. Solution is calculated on the basis of FEM. The Frequencies of modal analysis in existing and optimized shafts are nearly equal and the peak frequencies are also nearly same as listed in below table. Table - 1 Frequencies Set Existing Frequency Optimized Frequency Hz Hz Hz Hz Hz Hz All rights reserved by 219

3 Hz Hz Hz Hz V. FATIGUE ANALYSIS Fatigue or metal fatigue, is the failure of a component as a result of cyclic stress. The failure occurs in three phases: crack initiation, crack propagation, and catastrophic overload failure. The duration of each of these three phases depends on many factors including fundamental raw material characteristics, magnitude and orientation of applied stresses, processing history, etc. Fatigue failures often result from applied stress levels significantly below those necessary to cause static failure. One of the key limitations to the S-N curve was the inability to predict life at stress ratios different from those under which the curve was developed. In predicting the life of a component, a more useful presentation of fatigue life test data is the modified Goodman Diagram. These diagrams, while still limited by specimen geometry, surface condition, and material characteristics, afford the user to predict life at any stress ratio. Typically, modified Goodman diagrams are developed for specific applications. Use of the diagram is also limited to that application. Calculation of damage intensity is straightforward once the cycle amplitude distribution is known. This distribution can be obtained from a time-history simply by counting cycles. In ansys the Fatigue analysis is done with the help of ansys Workbench of the intermediate steering shaft. In this Fatigue analysis the total deformation Life of the intermediate steering shaft and the safety factor and the von mises stress are calculated by applying the loads and the boundary conditions. A. Fatigue Analysis of Existing Intermediate Steering Shaft: Following are the Factors which are calculated of existing shaft as below:- 1) Total Deformation: 2) Von-Mises Stress: Fig. 1: Total Deformation under Fatigue Analysis in Existing Fig. 2: Von-Mises Stress under Fatigue Analysis in Existing All rights reserved by 220

4 3) Safety Factor: Fig. 3: Safety Factor under Fatigue Analysis in Existing 4) Life: Fig. 4: Life under Fatigue Analysis in Existing B. Fatigue Analysis of Optimized Intermediate Steering Shaft: Following are the Factors Which are calculated of optimized shaft as below:- 1) Total Deformation: 2) Von-Mises Stress: Fig. 5: Total Deformation under Fatigue Analysis in Optimized Fig. 6: Von-Mises Stress under Fatigue Analysis in Optimized All rights reserved by 221

5 3) Safety Factor: Fig. 7: Safety Factor under Fatigue Analysis In Optimized 4) Life: Fig. 8: Life under Fatigue Analysis in Optimized From above figs. it is clear that total deformation in existing is 0.022mm and in optimized is mm so it is less in optimized and von mises stress in existing is MPa and in optimized is MPa it is also less in the optimized intermediate steering shaft so the optimized design is better. Safety Factor in existing one is and in optimized is and the maximum is 15 and the Life of both the existing and the intermediate steering shaft at the maximum is same i.e 1e6 is equal to the 1lakh cycles. VI. LIFE CALCULATIONS Life Calculations of the both intermediate steering shaft existing and optimized. A. Life of Existing Intermediate Steering Shaft: For the life calculations Peak frequencies are necessary and the peak frequencies are taken from the modal analysis. By taking the average of first four frequencies i.e peak frequencies Cycles per min(cpm) are found out as CPM. Later this CPM is further converted into Cycles Per Days(CPD) as = = CPD Maximum number of cycles in Existing is 1e6 i.e1lakh cycles Life of intermediate steering shaft in days is = Cycles / CPD =10 6 / =69.347days. Life of existing intermediate steering shaft in days is days. If the average speed of the car is taken as50 Km/hr then Life of the shaft in Kms can be calculated as Life in Kms = = Kms The existing intermediate steering shaft has life of Kms. All rights reserved by 222

6 B. Life of Optimized Intermediate Steering Shaft: For the life calculations Peak frequencies are necessary and the peak frequencies are taken from the modal analysis. By taking the average of first four frequencies i.e peak frequencies Cycles per min(cpm) are found out as CPM. Later this CPM is further converted into Cycles Per Days(CPD) as = = CPD Maximum number of cycles in Existing is 1e6 i.e1lakh cycles Life of intermediate steering shaft in days is = Cycles / CPD =10 6 / =75.164days. Life of optimized intermediate steering shaft in days is days. If the average speed of the car is taken as50 Km/hr then Life of the shaft in Kms can be calculated as Life in Kms = = Kms The optimized intermediate steering shaft has life of Kms. Table 2 Fatigue Analysis Results Sr. No. Fatigue Analysis Existing Optimized Fatigue Analysis 1 Total Deformation 0.022mm mm Total Deformation 2 Von mises Stress MPa MPa Von mises Stress 3 Safety Factor Safety Factor 4 Life KMs KMs Life VII. CONCLUSION From above results it is clear that the existing steering shaft has more deformation more stress and less life than the optimized intermediate steering shaft. Hence from the above discussion all the result values of the existing and the optimized and the theoretical calculations matches or are effective than existing so the design of the optimized intermediate steering shaft will be beneficial. REFERENCES [1] Kenneth L. Oblizajek and John D. Sopoci "Small Amplitude Torsional Steering Column Dynamics on Smooth Roads:In-Vehicle Effects and Internal Sources"SAE International Published 04/12/2011 [2] B.Babu, M. Prabhu, P.Dharmaraj, R.Sampath "Stress Analysis On Steering Knuckle Of The Automobile Steering System"IJRET Volume: 03 Issue: 03 Mar [3] Bhushan Akhare and Sanjeev S. Chouhan Performance and Value analysis of Power steering system IJETAE Volume: 2 Issue: 08 August [4] K. Lohith Dr. S.R. Shankapal,M.H Monish Gowda Development of four wheel steering system for a car Volume: 12 Issue: 01 April [5] D. Toffin G. Reymond, A Kemney, J. Droulez Influence of Steering Wheel Torque Feedback in a dynamic driving Simulator. [6] Dan Xiang, Jian-zhong Yuan, Wei Xu "Study on Fuzzy PID Algorithm for a New Active Front Steering System " JCET Vol.2 No.1 January 2012 PP [7] Rinse Winse Dhanesh Chatta and Ashish Nair Dept. of Mechanical Engineering, Govt. College of Engineering Kannur, Kannur, Kerala. Design of Pneumatic Collapsible Steering (IJTARME) Volume-2, Issue-2, [8] Hiroyuki MIYAZAKI Engineering Planning Department "Technical Trends In Steering Systems." JTEKT Corporation Proceedings of the 7th JFPS International Symposium on Fluid Power September 15-18, [9] Naresh Kamble, S.K Shaha, Rajesh Priyadarshani Virtual Prototype of Rack and pinion Steering Gear meshing SAE INDIA All rights reserved by 223