Mechanical Properties Of Shape Memory Alloy Composite Laminates

As a kind of intelligent material,shape memory alloy can return to its original shape under the stimulation of external environment(temperature,electricity and magnetism,etc.).Due to its unique superelasticity and shape memory effect,it has been paid great attention in shipbuilding,aerospace industry,construction industry,automobile manufacturing and other fields.Shape memory alloys and their composites have been extensively studied and put into practical application.Many mechanical properties of matrix materials can be changed by embedding shape memory alloys into matrix materials in the form of wires,films,particles,fibers or ribbons,which realizes special functions that many materials cannot achieve.In this paper,the shape memory alloy/glass fiber reinforced resin matrix composites were prepared by vacuum assisted resin infusion process,and the static and dynamic properties of the composites were studied.The following aspects have been researched in detail:(1)The interface properties of shape memory alloy composites are analyzed by fiber pull-out test,and the improvement of interface properties of composites by different surface treatment methods is studied.The microstructure characteristics of different surface treatment methods are researched by scanning electron microscopy(SEM)and interface mechanical properties analysis.(2)Several macroscopic phenomenological constitutive models of shape memory alloys are introduced,including one-dimensional and multi-dimensional constitutive models.The constitutive relations of SMA composites under different conditions are given.The damage process is described based on hashin progressive damage model and bilinear damage evolution rule,the damage model required for the finite element model of SMA composite laminates is established.(3)Shape memory alloy composite laminates are prepared by vacuum-assisted infusion processing.The effect of the content and position of SMA wire on the static properties of glass fiber reinforced epoxy resin(GF/epoxy)composite laminates is studied.According to the influence of different content and position of SMA wire on the mechanical properties of composite laminates,the optimal content and position of SMA embedded in composite laminates are obtained.The effect of interfacial properties on the mechanical properties of the SMA composites embedded with SMA wires is investigated by means of mode I and mode II interlayer fracture toughness test and SEM analysis.The finite element models of GF/epoxy composite and SMA composite laminates are established.The simulation results and experimental results are compared to verify the validity of the models.According to simulation results of finite element models,the optimal position and content of SMA embedded in laminates are given.(4)The fatigue properties of composite laminates embedded with are experimentally studied.The effect of the content and position of SMA embedded laminates on the fatigue performance of the laminates is investigated.Under the same stress level,three fatigue parameters are used to measure the fatigue properties of SMA composite laminates.The fatigue life of two SMA wires composites is about twice that of common GF/epoxy composites.SMA deformation can suppress the matrix cracks and reduce the crack growth rate,which helps to improve the fatigue life of GF/epoxy composites with SMA.The fatigue failure mode of composites is similar to the fatigue failure mode of static load failure mode.Compared with experimental results,the numerical results are well agreed with experiments.(5)The effect of the temperature on the impact response of the shape memory alloy composite is experimentally studied.As the temperature decreases,the low velocity impact properties of both composites improve.At temperatures in the range of-50 to 25 °C,the impact influence of SMA composites is significantly higher than GF/epoxy composites.The maximum force of GF/epoxy and SMA composite specimens decreases with increasing temperature,and the maximum strength increases with the impact energy.(6)The impact response of composite laminates containing shape memory alloy is simulated by finite element method,and glass fiber reinforced composites and shape memory alloy/glass fiber hybrid composites were selected as the model system.The impact damage model of shape memory alloy composite laminates is established,and the impact damage mechanism of composite laminates is analyzed,and the numerical results are compared with the experimental results.The critical energy value of impact damage of shape memory alloy hybrid composites is found by finite element method.