Lightweight Design And Mechanical Properties Analysis Of Fiber Reinforced Composite Leaf Spring Structure

In recent decades,the development of civil engineering construction has made remarkable achievements.The application of new materials,for instance the composite materials,has also greatly improved the efficiency and quality of construction,and have tackled the problems existing in the traditional construction materials.However,with the wide use of composite materials,problems have gradually become prominent,such as the high cost of many composite materials,the waste scraps produced in the manufacturing process which may cause greater pollution to the environment,the recycling problem of composite materials after long-term service.Therefore,selection of green,sustainable and cost-effective composite materials to be applied in practical projects can help to reduce the burden on the environment is of great significance to promote the development of green buildings in China.In this paper,the natural flax fiber reinforced composite material is taken as the object to investigate its feasibility of being used to make load-bearing cantilever components.And a typical cantilever beam structure(leaf spring)with comprehensive application valueis taken as the research object.Firstly,different fiber reinforced composite materials are selected to design and replace the traditional metal leaf spring structure,including carbon fiber,E-glass fiber,Kevlar fiber and environment-friendly flax fiber(which has similar mechanical properties to E-glass fiber).After verifying the feasibility of using flax fiber reinforced composite material for the cantilever bearing components,the structure optimization of flax fiber composite leaf spring structure was further conducted.The related mechanical properties and structure safety is analyzed,and a procedure for lightweight design of the flax fiber reinforced composite load bearing cantilever component(leaf spring)is proposed.Firstly,several common synthetic fiber composite materials were applied to replace the monolithic metal leaf spring under light load conditions,and has preliminarily proved the feasibility of using fiber reinforced composite materials to replace the metal leaf spring.On this basis,the E-glass fiber composite materials and flax fiber composite materials(both of which have close mechanical properties)leaf spring were further compared of the performance,including the weight loss rate,safety coefficient,mechanical properties and so on.It is proved that the flax fiber composite leaf spring has superior advantages in weight reduction and environmental protection than the common E-glass fiber composite leaf spring.Then,the leaf spring structure under heavy load environment was further studied,and two kinds of flax fiber reinforced composite leaf spring structures were designed and optimized respectively.The results show that the single-piece variable-thickness flax fiber composite leaf spring can still meet the performance requirements of the whole vehicle under the condition of full load,but the equivalent stress of certain leaf of the three-piece flax fiber leaf spring is close to the stress limit of the flax fiber composite.To solve this problem,a kind of combined plate spring scheme was put forward to replace the flax fiber spring(which bears great stress)with glass fiber reinforced composite leaf.In conclusion,the research results of this thesis indicate that it is feasible to use environment-friendly flax fiber composite material to replace the commonly used E glass fiber composite material to manufacture load bearing components.Under the premise of satisfying the target performance of load-bearing components,the components designed by using flax fiber reinforced composite materials are lighter,more environmentally friendly and have higher economic benefits.The work in this thesis and the conclusions can provide valuable references for practical engineering,such as the design and mechanical performance analysis of the cantilever bearing structure in the field of civil engineering.Meanwhile,the research on the environment-friendly flax fiber reinforced composites as load carrying components has open a door for its future development and application as green building materials in civil engineering.