Investigation On The Damage Mechanism Of Gfrp Laminates With A Semicircular Arch Subjected To Low-velocity Impact

Composite materials are widely used in aerospace,wind power generation,automobile,medical treatment,infrastructure,and other fields because of their good mechanical properties and excellent adaptability.With the development of modern manufacturing technology,complex hybrid structures can be made of composite materials instead of simple flat plates.These improvements help to reduce the number of parts and connectors,thus improving the production efficiency and mechanical properties of products.At present,the composite structure with arc arch surface is more and more widely used,and the composite structure is easily affected by low-velocity impact in the process of manufacture and use.Therefore,the research on low-velocity impact of hybrid structural composites with arc camber can provide theoretical support and application reference for the design of composite components.Vacuum-assisted resin infusion(VARI)process was used to form four kinds of glass fiber composite plates with different arc arches with curvature radii of 0 cm,1 cm,2 cm and 3cm.In order to study the influence of low-velocity impact and curvature on composite plates with arc structures,low-velocity impact,and post-impact compression tests were carried out.At the same time,a static compression test method is designed to test the out-of-plane compression of composite plates with arc structure,and finite element analysis is supplemented on this basis.The specific research contents are as follows:(1)Low-velocity impact tests were carried out on curved plate specimens with four different radii of curvature.The composite plates were impacted by different energy,and the damage morphology after impact was recorded and analyzed by the camera and scanning electron microscope,and the impact response laws of four kinds of arc plates with different curvature radii under low-velocity impact load were obtained.The results show that the specimen with curved arch surface is more sensitive to impact than the flat specimen,and the bearing capacity of the curved plate in the process of low-velocity impact is borne by the curved area and the whole area of the curved plate.When the impact energy is small,the damage caused by the flat plate with the radius of curvature of 0 cm is mainly fiber delamination damage.The glass fiber composite arc plates with curvature radius of 1 cm,2cm and 3 cm produce elliptical and rhombic delamination damage in the impact area,and the resin matrix appears transverse and cross cracks,and the damage degree increases with the increase of impact energy.By analyzing the change of curvature radius of the arc region,it is found that when the curvature radius of the arc region is consistent with that of the impactor,the impact resistance of the arc region gradually decreases with the increase of impact energy,but the overall impact resistance gradually increases.When the curvature radius of the arc arch surface is greater than that of the impactor,the impact resistance and deformation resistance of the arc region of the specimen gradually increases with the increase of the curvature radius of the arc region,but the overall impact resistance begins to decrease.(2)The post-impact compression test was carried out on four different specimens after the low-velocity impact test.The mechanical response of the specimen was recorded during the compression test after impact,and the changes of strain and displacement field of the specimen during compression were measured by 2D-VIC technology.After obtaining the corresponding data,the residual compressive strength of different specimens under different impact energy and the damage development of different specimens during compression were analyzed.The results show that with the increase of impact energy,the damage degree of the specimen is aggravated,and the internal stress concentration is more serious in the process of compression after impact,which leads to the decrease of residual compressive strength after impact.(3)A static compression test method is designed,and the out-of-plane compression tests are carried out on four kinds of specimens with curved arch surfaces.Combined with 3D-DIC technology and ABQUAS finite element analysis software,the damage of four kinds of specimens during static compression is observed.The mechanical response and damage evolution of four kinds of specimens under static compression are analyzed.The results show that the out-of-plane compression test is consistent with the finite element simulation results.During the static compression process,the specimen with curvature radius of 1 cm has two peaks,and its second peak bearing capacity is increased by about 46.27% compared with the first peak force.However,the bearing capacity of specimens with curvature radius of 2 cm and 3 cm appears as a buffer zone after decreasing.It is proved that the bearing capacity of the specimen is borne by the arc region and the whole arc plate region in the process of low-velocity impact,and it is found that setting the curvature radius of the arc arch surface region reasonably can affect the stiffness and overall deformation ability of the material.