Effect Of Seawater On The Static And Cracking Of PVC Foam Sandwich Panel

Composite foam sandwich structure is one type of advanced composite structures,and it has many incredible features,such as high strength,light weight,good stability,good heat and sound isolation,corrosion resistance and so on,so it has been widely used in marine engineering fields.Furthermore,compared with the traditional single material,fatigue resistance,shock resistance,noise reduction has made its promising application prospect especially in the field of marine engineering structure and ship engineering.There are many kinds of composite materials in the composite foam sandwich structure.Among them,the most widely used composite materials are sandwich panels which is made by GFRP(glass fiber reinforced plastic)face plates and PVC high strength foam core.For marine fiber reinforced composite foam sandwich structure,research on foam sandwich mainly focused on seawater diffusion mechanism in the sandwich structure,erosion of PVC foam or sandwich structure in moisture environment,and influences of environmental factors.However,there is few study on the fracture toughness between layers.In this paper,we mainly study the effects of seawater on the fracture toughness of sandwich with GFRP face plates and PVC foam core.The main contents are as follows:Firstly,foam sandwich with two different types of cores(H60 and H200 PVC foams)are manufactured by VARTM.Then DCB standard specimens are prepared with a sink cutter and immerged in a constant temperature simulated seawater with a solubility of 3.3% and 25?and 60? temperatures respectively.After a period of time,the effects of seawater on the tensile properties of GFRP panels,the compression properties of PVC sandwich foams,and the three-point bending properties of sandwich structure under different immersion time and temperature were investigated respectively.Energy release rate is a key factor of sandwich structure's fracture toughness,so DCB experiments are conducted to determine the energy ratio of interlayer cracking.Firstly,the DCB experiments on H60 and H200 PVC foam core in a seawater-free environment were carried out.The difference of crack propagation path between the two types of cores were measured and the corresponding energy release rate was calculated.In same principles,the DCB experiments in different immersion time and different immersion temperature were carried out to explore the loading rate on the interlayer cracking.By using of cohesive model in ABAQUS,the DCB experimental simulation of two types of core sandwich plates immersed in seawater and fresh water for 90 days environment were carried out respectively.In addition,the H60 core sandwich structure subjected to DCB simulation in different loading rates,and the simulation results can verify the accuracy of the experiments.