Cement Pump Truck Structural Strength

In this dissertation, the theories of finite element and fatigue strength are discoursed systematically. Under the direction of these theories, using of MSC/NASTRAN and MSC/FATIGUE software, a bump auto which pipes concrete is analyzed on static strength, mode, time domain strength, frequency domain strength and fatigue strength. With these comprehensive study, the fragile region of construction strength, the reason of serious vibration and the weak element of fatigue strength are obtained, and relative improving treatments are given. The main contents can be summarized as follows:1 Comprehensive analyzing every working state of the pump auto , eight working states are selected to establish relative finite element modules.2 The maximum stress and the maximum stress location and the distribution of the stress are attained through the static analysis of building up finite element module. The finite element analysis results are approximative with relative testing results. The stress of horizontal working states is bigger than others, and the maximum stress attaches to 540 MPa. Only considering static strength, the bump auto satisfies command.3 Inherent vibration frequency and relative vibration shape of the bump auto working under various condition can be received from mode analysis. This thesis gives first six modes of the bump auto under given eight working states. The first inherent vibration frequency and the second one all lie in the interval of 0.3 8 ~ 0.41 HZ. The first inherent vibration frequency getting from testing lies in the interval of 0.3636~0.3924HZ. And working frequency of the bump auto lies in the interval of 20~24 times every minute, namely 0.33~0.40HZ. So that, the reason that causes serious branch vibration during the bump auto working is that the resonance happens.4 Circulation brunt load acting on given finite element modules, time domain strength analysis and frequency domain strength analysis are performed. Because of high sharp peak, vibration stress is big, and the maximum stress achieves 550MPa. Because structure inherent frequency affects vibration strength, frequency domain analysis results show that power signal density(PST) curve has two high peak during the frequency of 0.38~0.41HZ. So, there are two means to solve the problem that vibration stress is too big. One is to lower the dynamic load's peak, the other is to adjust off working frequency and inherent frequency.5 Component fatigue life curve(P-S-N curve) is used in fatigue life analysis.The thesis provides fatigue life whose possibility is 95% or 50%. The analysis results of fatigue life and weak elements agree with fact.With above-mention comprehensive analysis, rationality and reliability of the finite element modules are proved. The results that the thesis provides offer speculative basis to improve the bump auto's strength, and the method that the thesis study has good consultant valuation for similar structure strength analysis.