Strength and Performance Enhancement of Multilayers by Spatial Tailoring of Adherend Compliance and Morphology via Multimaterial Jetting Additive Manufacturing

Abstract

Material tailoring of bondlayer compliance is a known effective route to enhance performance of multilayers, and here spatial material-tailoring of compliance and morphology of the adherends is examined. Multimaterial jetting additive manufacturing (AM) allows us to realize for the first time compliance- and morphology-tailored adherends, and evaluate directly the mechanical performance, including failure, of the tensile-loaded multilayers. Adherend compliance-tailoring, unlike bondlayer tailoring, requires additional consideration due to adherend bending stiffness and moment influences on bondlayer stresses. We introduce anisotropic as well as layered/sandwich adherend tailoring to address this dependence. Numerical models show that for both sub-critical and critical bondlengths (at which shear-dominated load transfer occurs through the bondlayer), adherend tailoring reduces peak stresses significantly, particularly peel stress (reductions of 47–80%) that typically controls failure in such systems. At sub-critical bondlengths, the AM-enabled layered/sandwich adherend tailoring shows significantly increased experimental performance over the baseline multilayer: strength is increased by 20%, toughness by 48%, and strain-to-break by 18%, while retaining multilayer stiffness. The adherend tailoring demonstrated here adds to the techniques available to increase the performance of bonded multilayers, suggesting that adherend tailoring is particularly well-suited to additively manufactured multilayers, but can also have application in other areas such as layered electronics and advanced structural composite laminates.

Architected poly(lactic acid)/poly(ε-caprolactone)/halloysite nanotube composite scaffolds enabled by 3D printing for biomedical applications

“…The polymer composite scaffolds can be fabricated by various manufacturing techniques including phase separation, gas foaming and additive manufacturing (AM). Among these techniques, AM (also known as 3D printing) has emerged as one of the most suitable techniques for polymer scaffold fabrication as it offers design freedom [26][27][28][29][30][31][32]. Among various 3D printing techniques, fused deposition modeling (FDM), also known as fused filament fabrication (FFF), is a preferred method for the fabrication of polymeric scaffolds with microarchitected internal and external porous morphology in a controlled fashion [33,34].…”

Additively Manufactured Polyetheretherketone (PEEK) with Carbon Nanostructure Reinforcement for Biomedical Structural Applications

“…[8] FFF is the most widely used AM technique due to its ease of use, fast fabrication, cost effectiveness, and ability to produce complex geometries without involving postmachining. [11] A variety of polymers and their composites can be processed by FFF, such as acrylonitrile butadiene styrene, [12] polylactic acid, [13] polyamides, [14] polypropylene, [15] and polycarbonate. [16,17] AM of high-temperature structural (modulus in excess of 1 GPa) thermoplastics, such as PEEK, has received enormous attention because of their wide applicability in many areas, including aerospace, energy, and orthopedics.…”

Mechanical strength of adhesively bonded joints using polymeric additive manufacturing

“…To date, the mechanical characterization of the AM components or adhesive joints can be traced in the literature, but the interactions of AM parts bonded with structural adhesives has not been deeply investigated yet, with only partial studies about the bonding of AM plastic components being available. 23,24 On the design side, it is possible not only to reduce the stiffness of the adherends to lower the stresses at the bondline edges, 21 but also to tailor the surface roughness or add a surface pattern to promote mechanical interlocking of the adherends. This additional feature will also improve the adhesion with the typical substrates used in AM, either metallic or polymeric, as studied in Dugbenoo et al 25 for composite parts.…”