Analysis And Design On Probability And Interval Reliability Of Composite Pressure Vessel

Pressure vessels capable of storing high-pressure gases,liquids and other substances are the key components commonly used in spacecraft.In the early aerospace equipment,pressure vessels were mostly made of high-strength steel,titanium and some alloys.In recent years,the composite pressure vessel is widely used in aerospace and other fields due to its advantages such as high specific strength and good corrosion resistance.However,due to the obvious heterogeneity of composite materials,adopting a scientific and reasonable method for structural design can achieve safety while taking economy into consideration.In order to solve this problem,most probabilistic reliability design and analysis methods are used.The method takes all the basic design parameters of a composite material as a random variable,predicts and analyzes the failure probability of the structure based on the probability distribution Method,scientific and reasonable.However,the method of probabilistic reliability has limitations.Especially for the problem of small samples and poor information,the probability and reliability of the method have some limitations.For example,the probability statistics of uncertain parameters are difficult to obtain or cannot be obtained at all.In this case,the method of interval reliability will be more reasonable method.Since this method does not need the probability and statistical properties of uncertain parameters,it only focuses on the interval of uncertain parameters,so it is used as a supplement to the probabilistic method.The main contents of this thesis are as follows:1.Reliability Analysis and Optimal Design of Composite Pressure Vessel Based on ANSYS:The physical properties of the composites of the composite pressure vessel analyzed in this thesis are briefly introduced.Then the finite element analysis results of the composite pressure vessel are analyzed and the results of stress-strain are discussed.ANSYS reliability analysis of random variables selection and reliability analysis criteria,the reliability analysis of the results are discussed.The optimal design of the composite pressure vessel with ANSYS optimization technique is carried out.First,the transient dynamic analysis is carried out to find the pressure load that can generate the maximum hoop strain.Then,the zero-order and first-order optimization provided by ANSYS method,the composite material pressure vessel is optimized and analyzed,the optimization results are obtained and the reliability is verified.The results show that the obtained optimization results meet the reliability requirements,and the result is the smallest total strain.2.Probability and Reliability Analysis and Design of Composite Pressure Vessel:Considering the randomness of parameters and loads in the structure of composite pressure vessel,the reliability analysis model of this type of pressure vessel is established.The stochastic factor method is used to derive the mean and standard deviation of the fiber stress expression.The probability and reliability method is used to realize the reliability design of the container.Finally,the influence of the fluctuation of random parameters on the thickness design of container is investigated.The results show that the results of probability and reliability design meet the safety requirements and are more reasonable than the results of traditional safety factor method3.Interval Reliability Analysis and Design of Composite Pressure Vessel Based on Interval Factor Method:Firstly,the interval reliability analysis model for this type of pressure vessel is established.The calculation formulas of mean,standard deviation and dispersion of fiber stress are derived by the method of interval factor.By using non-probabilistic reliability calculation method,the non-probabilistic reliability design was also investigated.The influence of structural parameters on the thickness of the container is investigated.The results show that the results of interval reliability design meet the safety requirements,but the accuracy is not high with the method of probability and reliability.4.Reliability Analysis and Design of Composite Materials Pressure Vessel Based on Improved PSO Algorithm:The reliability analysis model of this type of pressure vessel is established considering the interval of each parameter and load in the structure of the composite pressure vessel.The interval reliability method and the improved PSO interval optimization algorithm are applied to realize the interval reliability design of the container.Finally,the influence of the fluctuation of structural uncertainty parameters on the design thickness of container is investigated.The results show that the results of interval reliability design based on improved PSO algorithm meet the safety requirements.Interval reliability design based on improved PSO algorithm Relative to the probability of reliability design,the calculation is relatively simple and easy to program.