This Post is currently under construction. Trying to get some resources outlined and gather any customer feedback about needs in this area.
Modeling of adhesives usually implies both the modeling of the constitutive (stress-strain) behavior and the damage and failure behavior. SIMULIA has been adding functionality to Abaqus/Standard and Abaqus/Explicit for over a decade to model damage and failure of various materials. The kinds of modeling techniques used to model adhesives are very similar to those used to model composites. So, the first reference material I would recommend is to take the Advanced Abaqus course "Analysis of Composite Materials with Abaqus". That course has both lecture presentations and workshops on several modeling techniques of interest, including cohesive elements, cohesive surfaces, and VCCT. Another resource is our Advanced Abaqus course on "Modeling Fracture and Failure with Abaqus". This course also covers the cohesive element technology and additionally the general XFEM capability in Abaqus.
A few key points about terminology :
1) “Structural adhesives” are common in the auto industry. They are thicker and stiffer, typically they are epoxy based.
2) “PSAs”, pressure sensitive adhesives, are thinner and more flexible. They are typically elastomer or polymer based.
Another good SIMULIA resource is the ClientCare QA article #8540 "Selecting Material Parameters in Abaqus for Cohesive Elements Defined in Terms of Traction-Separation". This article was written in the ~2007-2008 time frame and was heavily influenced by two SCC/AUC papers by Ted Diehl from the 2005 and 2006 AUCs. All three of these papers are attached to this post in a zip file. These papers, and others from the same time frame keep the constitutive relation very simple – a traction-separation law representing linear elasticity. The failure of the bond is considered to be only interfacial and is commonly represented by cohesive elements with 'damage initiation' and 'damage evolution' behaviors defined. In our composites class we have a nice workshop problem, WS4, "Analysis of a DCB using Cohesive Behavior". The "DCB" is the double-cantilever beam, and it is a common test that is used to understand the behavior of adhesive joints. Reading the 3 papers attached to this post, taking the composites class, and working through the course workshop WS4 are a great first step in understanding how to model adhesive behavior.
Reading through more recent papers on adhesive modeling, with a focus on PSA's, there are a variety of papers that claim that for these softer materials a more detailed constitutive modeling is required. There are several good and recent papers from Imperial College, a group that has been researching adhesive behavior and modeling for over a decade.
Modelling the interfacial peeling of pressure-sensitive adhesives by I.K. Mohammed, M.N. Charalambides, A.J. Kinloch, Journal of Non-Newtonian Fluid Mechanics 222 (2015) 141–150
Modelling the Peeling Behavior of Soft Adhesives, by I.K. Mohammed, A.J. Kinloch, M.N. Charalambides, available online at www.sciencedirect.com
Some additional issues:
1) Modeling Best Practices. This could be a catch-all. For instance: is the constitutive model of the adhesive material important?
2) Rates. How to handle the rate situation? Many standard tests are performed at slow rates. Drop testing of electronics is a common application – how to model the adhesive failure at high rates ?
3) Thermal. Thermally driven deformations and failure is another use case in the electronics industry. Having constitutive models for the substrate and adhesive that respond correctly to thermal changes is important.
4) Testing. What are the typical test performed ?
5) Calibration.
6) Crack Path ; Adhesive versus Cohesive failure.
7) Fracture Mode / Mode Mixity issues
8) Mesh Sensitivity / mesh dependence
9) Defects, Manufacturing variability
