Study the Temperature Effect on the Dynamic Response for a Camshaft by Using the Combined Finite Element - Transfer Matrices Method

توفيق, موفق علي; رشيد, زيد حكمت

doi:10.30684/etj.28.8.17

	Study the Temperature Effect on the Dynamic Response for a Camshaft by Using the Combined Finite Element - Transfer Matrices Method
Engineering and Technology Journal
Article 1, Volume 28, Issue 8, 2010, Pages 347-375 PDF (355.15 K)
DOI: 10.30684/etj.28.8.17
Authors
موفق علي توفيق; زيد حكمت رشيد
Abstract
The present work studies the effect of temperature on the dynamic response for a camshaft as rotor –bearing system contains branches. The effect of temperature distribution along camshaft length on the critical speeds and on the distribution of lateral amounts of vibration (eigen mode) along camshaft length with three dimension are accounted for. Also this work considers the multi effect of temperature distribution and bearings number and its positions. The response has been calculated at different interval of time with different temperatures. The study has been applied on petrol engine camshaft of Volkswagen 1994 car with 4 cylinders; the camshaft has 8 cams, 5 bearings, total length of 39.5cm and total weight of 2.32Kg working with rang (20-80Cº) and SAE 40 oil type. The dynamic investigation of the camshaft has been achieved depending on the combined Finite Element – Transfer Matrices technique (FETM). It is accounted for the shear effect and gyroscopic effect of camshaft gear and the effect of unbalance forces resulting from the existence of the out of balance of the shaft and cams masses, Also it considered the dynamic loads that are applied on the cams surfaces and the temperature effect on the material elasticity and rigidity. Eight coefficients of damping and stiffness have been computed for each bearing at each angle of rotation with the considering of the temperature effect on the bearing's oil viscosity. A FORTRAN language computer programs have been developed to embrace the theoretical work, the programs are able to calculate the camshaft dynamic response and its critical speeds, Also calculating forces on cams surfaces as a function of camshaft rotation angle. It has been found that there are a certain critical speeds and eigen modes for each temperature distribution, In general case, the results show that the critical speeds values decrease as temperature increases and the gradient in the speeds depends on the rank of critical speed. Also it has been found that the reduction of bearings number leads to reduce the values of critical speeds and the reduction ratio depends on temperature and the rank of critical speed. Also it has been found that the distribution of lateral amounts of vibration are affected by the eight coefficients of the bearing wich are changed according to the temperature, speed and camshaft rotation angle.

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