Effect Of Surface Structure Design On Adhesive Properties Of Additive Manufacturing Parts

Additive manufacturing?AM?is a new manufacturing process that has developed rapidly in recent years.Because it can be designed to produce structural components of any shape,it can minimize the weight of structural components while ensuring the strength of the structural components.Bonding traditional structures with additive manufacturing structures is a very significant way to reduce costs.In this dissertation,the two most widely used AM technologies,fused deposition molding?FDM?and selective laser sintering?SLS?with high printing accuracy,are used to systematically study the effect of surface structure on adhesion performance.The research results of this paper are as follows:?1?Adhesive bonding of additive manufactured coupons of polyetheretherketone?PEEK?and polyetherimide?PEI,ULTEM 9085?by fused deposition modelling are studied.Four adherent surface microfeatures,groove,square,semi-sphere and step-cone,have been designed and optimized by single-lap joint?SLJ?testing,double cantilever beam?DCB?testing and finite elemental analysis?FEA?.Surface features and plasma pre-treatment have profound effect on the adhesion strength.For both SLJ and DCB,the adhesive bonding strength decreases following the order of step-cone>square?sphere>grooves.Different from the traditional microstructure,the surface macrostructure size is larger,and the adhesion?or wetting?between the adhesive and the bonding surface is not improved,but the interlocking effect between these structures makes the edge of the bonding surface stress The dispersion to the middle weakens the stress concentration problem to a certain extent.FEA results indicate that the surface“Micro”features?5-20?m?improves the adhesive bonding strength through interlocking of adhesive and microfeatures.While in DCB testing,cohesive failure is observed and the volumetrically-increased surface area available for bonding provides additional promotion on the bonding strength.?2?The selective laser sintering process was used to study the effects of building directions and fiber orientation on the bonding performance of the carbon-fiber-reinforced polyamide 12 coupons manufactured by selective laser sintering were studied.For double cantilever beam joining,the mode I interlaminar fracture toughness(G_IC)of the side surface is nearly 4 times higher than that of the top surfaces,and 2.5 times higher than that of the bottom surfaces.We identified the improvement in fracture properties as a combination of higher surface roughness and fiber orientation.With the fiber aligned perpendicular to the bonding surface,the fiber-tear failure can be suppressed to the greatest extent,resulted in the highest fracture toughness(G_IC=2600 J/m²).