Study On Prediction Of Interlayer Mechanical Properties And Load-bearing Failure Of FDM Products

Fused Deposition Modeling(FDM)is a rapid prototyping technology developed rapidly in the field of 3D printing technology.There are some advantages of FDM including not using laser forming manufacturing system,low cost,wide application materials and personalized customization.Therefore,it is widely used in mold design,new product development and medical treatment.For the process of FDM,the polymer fiber is heated,melted and extruded through a nozzle,and the layers are accumulated.The molding characteristics result in weak adhesion between adjacent wires,and the overall strength of the FDM product is lower than other molding techniques.The application is subjected to a certain degree of restriction.Therefore,reasonable prediction of the bond strength is of great significance for the load endurance evaluation of FDM products.The bonding mechanism in FDM process was illustrated firstly.Both ABS and PA were chosen as molding materials.Based on polymer molecular diffusion theory and rheological properties,combined with experiments and heat transfer analysis,a predictive model for the bond strength between layers of FDM products was established.The prediction results are close to the experimental results,indicating that the model can predict the interlayer bond strength of FDM parts greatly,which provides an important basis for the evaluation of the overall strength of the FDM products.The prediction model is expanded to Elastic Modulus prediction.The prediction results show that the model after correction can be used to predict Elastic Modulus effectively.Based on the prediction of the interlayer bond strength and modulus of FDM product,the model was further extended to the performance prediction of the interlayer shear direction.The shearing experiment and fixture were designed firstly.Then the predictive model of interlayer shear strength of FDM products was reasonably derived.The results indicate that the model can be used to predict the interlayer shear strength of FDM products,and will be powerful theoretical basis for FDM product service analysis.Combining experiments with simulation to verify and apply the predictive model of interlayer adhesion strength and modulus.Firstly,a three-point bending experiment was designed.And then,using the strength and modulus predicted by the model as failure criteria to simulate the failure process of three-point bending by ABAQUS software.The simulation results show that the experimental results are in good agreement,and the rationality of the model is verified.Then we select the hook and the bracket as the research objects,and compare the experiment and simulation to analyze the bearing performance of the structures.The simulation results show that it is in good agreement with the experimental results,which indicates that the predictive model can be used as an effective model for predicting the bearing performance of FDM products.