钢-CFRP胶接接头疲劳损伤特性试验研究
发布时间：2018-11-05 17:57
【摘要】：基于节能与环保的需求,近年来结构轻量化在车辆设计领域受到广泛关注。在车身应用方面,使用高性能轻质材料替代传统钢材(如CFRP)是实现轻量化最为有效的方法之一。短期时间内,轻质材料难以完全替代传统车身材料,异质材料在车身结构中的共同应用则会带来一系列连接问题。与传统连接方式相比,胶接技术质量轻、应力分布均匀、密封性好、抗疲劳强,在异质材料连接方面具有较大优势。相对于传统连接方式,胶接接头服役性能研究较为有限,因此制约了其在汽车制造领域的应用。车辆在服役过程中,异质材料连接部位由于长期受到地面动态载荷的激励而可能发生破坏,而对关键部位疲劳寿命的准确预测能够保证车身达到轻量化的同时满足车身疲劳性能的要求。目前对于金属胶接接头疲劳的试验研究与数值仿真都较为完善,然而仍然缺乏对复合材料-金属胶接接头疲劳服役性能方面的研究。本文以复合材料基础力学性能与钢-CFRP胶接接头在恒幅载荷下疲劳损伤特性为研究对象,主要开展了以下几个方面工作：(1)使用试验方法与理论模型分别对某型复合材料与接头基底CFRP材料宏观力学性能进行了研究。通过制造相应夹具,对某型复合材料标准试件进行了准静态基础力学性能测试,得到了该复合材料准静态拉伸、剪切以及压缩力学性能参数；使用复合材料宏观力学模型与Halpin/Tsai模型分别获取了接头基底CFRP材料基础力学性能参数,同时基于两种不同材料参数值在ABAQUS(?) CAE中建立了CFRP准静态拉伸有限元模型,通过与试件拉伸试验结果对比选取较为接近的仿真模型。(2)使用试验方法对钢-CFRP胶接接头在恒幅载荷下疲劳损伤特性进行了研究。基于全寿命疲劳测试方法获取了钢-CFRP胶接接头在特定恒幅载荷下的疲劳寿命,使用背面应变法记录了接头胶层裂纹扩展过程中背部应变变化情况,同时以不同加载周期接头的剩余强度与固有频率变化值对胶层疲劳损伤特性进行了研究。通过分析接头在不同加载周期刚度与强度的退化情况研究了接头疲劳损伤对其静态与动态性能的影响。
[Abstract]:Based on the demand of energy saving and environmental protection, structural lightweight has been paid more and more attention in the field of vehicle design in recent years. In body application, the use of high performance lightweight materials to replace traditional steel (such as CFRP) is one of the most effective methods to achieve lightweight. In the short term, lightweight materials can not replace traditional body materials completely, and the joint application of heterogeneous materials in body structure will lead to a series of connection problems. Compared with the traditional bonding technology, the bonding technology has the advantages of light weight, uniform stress distribution, good sealing and fatigue resistance, and has great advantages in the connection of heterogeneous materials. Compared with the traditional connection mode, the service performance of adhesive joint is limited, so its application in automobile manufacturing field is restricted. During the service of the vehicle, the connection part of heterogeneous material may be destroyed because of the excitation of dynamic load on the ground for a long time. The accurate prediction of the fatigue life of the key parts can ensure the lightweight of the body and meet the requirements of the fatigue performance of the body. At present, the fatigue test and numerical simulation of metal bonded joints are relatively perfect, but there is still no research on fatigue service performance of composite metal bonded joints. In this paper, the mechanical properties of composite foundation and fatigue damage characteristics of steel-CFRP joints under constant amplitude loading are studied. The main works are as follows: (1) the macroscopic mechanical properties of a composite material and a joint substrate CFRP material are studied by means of test method and theoretical model. The quasi static basic mechanical properties of a kind of composite material standard specimen were tested by making the corresponding fixture, and the mechanical properties parameters of quasi-static tensile, shear and compression of the composite were obtained. The mechanical properties of the CFRP material base on the joint substrate were obtained by using the composite macro mechanical model and the Halpin/Tsai model, respectively, and based on the values of two different material parameters, the mechanical properties of the CFRP material were obtained in the ABAQUS (?) The quasi-static tensile finite element model of CFRP is established in CAE, and the simulation model is chosen by comparing with the results of tensile test. (2) the fatigue damage characteristics of steel-CFRP adhesive joints under constant amplitude loading are studied by means of test method. Based on the whole life fatigue test method, the fatigue life of steel CFRP adhesive joint under constant amplitude load is obtained. The back strain method is used to record the back strain change during crack propagation of the adhesive layer of the joint. At the same time, the fatigue damage characteristics of the adhesive layer were studied with the change of residual strength and natural frequency of the joints with different loading periods. The effects of fatigue damage on the static and dynamic properties of joints were studied by analyzing the degradation of stiffness and strength of joints under different loading periods.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U465
本文编号：2312868
[Abstract]:Based on the demand of energy saving and environmental protection, structural lightweight has been paid more and more attention in the field of vehicle design in recent years. In body application, the use of high performance lightweight materials to replace traditional steel (such as CFRP) is one of the most effective methods to achieve lightweight. In the short term, lightweight materials can not replace traditional body materials completely, and the joint application of heterogeneous materials in body structure will lead to a series of connection problems. Compared with the traditional bonding technology, the bonding technology has the advantages of light weight, uniform stress distribution, good sealing and fatigue resistance, and has great advantages in the connection of heterogeneous materials. Compared with the traditional connection mode, the service performance of adhesive joint is limited, so its application in automobile manufacturing field is restricted. During the service of the vehicle, the connection part of heterogeneous material may be destroyed because of the excitation of dynamic load on the ground for a long time. The accurate prediction of the fatigue life of the key parts can ensure the lightweight of the body and meet the requirements of the fatigue performance of the body. At present, the fatigue test and numerical simulation of metal bonded joints are relatively perfect, but there is still no research on fatigue service performance of composite metal bonded joints. In this paper, the mechanical properties of composite foundation and fatigue damage characteristics of steel-CFRP joints under constant amplitude loading are studied. The main works are as follows: (1) the macroscopic mechanical properties of a composite material and a joint substrate CFRP material are studied by means of test method and theoretical model. The quasi static basic mechanical properties of a kind of composite material standard specimen were tested by making the corresponding fixture, and the mechanical properties parameters of quasi-static tensile, shear and compression of the composite were obtained. The mechanical properties of the CFRP material base on the joint substrate were obtained by using the composite macro mechanical model and the Halpin/Tsai model, respectively, and based on the values of two different material parameters, the mechanical properties of the CFRP material were obtained in the ABAQUS (?) The quasi-static tensile finite element model of CFRP is established in CAE, and the simulation model is chosen by comparing with the results of tensile test. (2) the fatigue damage characteristics of steel-CFRP adhesive joints under constant amplitude loading are studied by means of test method. Based on the whole life fatigue test method, the fatigue life of steel CFRP adhesive joint under constant amplitude load is obtained. The back strain method is used to record the back strain change during crack propagation of the adhesive layer of the joint. At the same time, the fatigue damage characteristics of the adhesive layer were studied with the change of residual strength and natural frequency of the joints with different loading periods. The effects of fatigue damage on the static and dynamic properties of joints were studied by analyzing the degradation of stiffness and strength of joints under different loading periods.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U465
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