A rigid-flexible multi-body system dynamic model of a passenger vehicle windscreen wiper system is established in this study to investigate the systems dynamic behaviour. To simulate the impact forces applied by the blades on the windshield and the pressure force distributions along the wiper blades, the blades are modelled as flexible bodies in consideration of their bend and twist deformations. On the basis of the dynamic analysis results, structure improvement measures, including changing the torsional stiffness of the neck of the blade segment and modifying the positions of the pivot points on the blades, are implemented to reduce the reversal impact and improve the wiping uniformity.
In this paper, as the multibody system dynamics analysis of one dieselpsilas pushrod-type valve train is concerned, the algorithm of calculation campsilas profiles from the lift of roller tappet is presented according to the kinematics analysis firstly. Then the flexible body models of the pushrod, rocker arm and valves that are considered to have significant flexibility are built. Comparing the analysis results with the experiment data, the flexible effects of these parts on dynamics characteristics of the valve train are determined. Based on these researches, the multi-flexible-body system dynamics model of this valve train is established, and the kinematics and dynamics characteristics under the enginepsilas rated speed are calculated. Moreover, the mechanismpsilas characteristics as the enginepsilas speed improved are predicted. The results shown that light lift-off occurs when the campsilas speed gets up to 1600 r/min, and valve bounce occurs when the campsilas speed gets up to 1900 r/min.
Compressive residual stresses and high hardness introduced by induction quenching are often used to improve the mechanical performance of crankshafts in engines. In this paper, in order to predict the fatigue strength of the crankshafts in a diesel engine accurately, the quenching process and the stress fields of the crankshaft are simulated by finite element method (FEM) and then the residual stresses are obtained. Quenching is a high non-linear process because of the coupling of the temperature, phase transformation and stress/strain fields. The transient temperature field is firstly solved using a quasi-coupling method to simulate the relationship of the temperature and the phase transformation. Based on the results of the temperature and phase transformation fields, the thermo-elastic-plastic analysis is then carried out to calculate the stress fields including the thermal stresses and the phase transformation stresses. At last the residual stress distribution at the room temperature is obtained.
Abstract The accumulation of small tangential slip will occur on the contact surfaces of components in mechanical structures when subjected to cyclic loadings, which will lead to system failure. However, the small tangential slip is difficult to measure directly. In this paper, a method for measuring the contact slip by using a self-powered displacement sensor based on triboelectric nanogenerator (TENG) is proposed, and the accuracy is verified by the finite element analysis (FEA). The contact slips for a flat-on-flat contact configuration are measured by this method. When the test piece is subjected to a cyclic tangential load with a frequency of 10Hz, the average obtained slip displacement of the test piece under single load cycle is less than 10μm. Then the finite element simulation of the contact configuration is carried out using software Abaqus 6.14. The analysis results are close to the test results, which verifies the effectiveness of the measurement method. Moreover, the slips of the flat-on-flat contact configuration under different frequency and amplitude of cyclic tangential load are investigated.
OBJECTIVE To establish a method for the determination of the papaverine content in Qiangli Pibalu by HPLC. METHOD A C18 column with a solvent system of acetonitrile-0.02 mol x L(-1) sodium dihydrogen phosphate (0.2% triethylamine, phosphoric acid, at pH 3) (25:75) and UV detection 240 nm were used. The flow rate was 1.0 mL x min(-1). The column temperature was maintained at 40 degrees C. RESULT There was a good linear relationship between the absorption value and the concentration in the range of 0.020 2-0.100 5 microg for papaverine. The average recovery rates were 99.1% (RSD 2.3%). CONCLUSION The method is simple, accurate and can be used to determine the contents in Qiangli Pibalu.
This paper presents the development of a dynamic model of the valve train of one engine. During the parameter determination of the model, finite element method is used to calculate the contact stiffness of the cam-follower . The simulation results of the model are compared with measured data of the valve train at same speed. Excellent quantitative agreement is found between the numerical and experimental results and the validity of the dynamic model can be verified.
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