Prediction of stress in the adhesive layer of a T peel specimen NPL has a long history of materials modelling. In recent years some of this modelling work has involved the use of finite element analysis (FEA). FEA is a useful tool, which allows the prediction of deformation behaviour, along with the visualisation of various parameters such as stress and strain distributions. Within the materials research area at NPL finite element analysis has been used routinely for a range of applications such as:

• modelling deformation behaviour of adhesives and adherends
• assessing the validity of test specimens/procedures
• a tool to asses the effect of geometric changes (parametric studies)
• predicting stess/strain concentrations - a way of predicting failure?

Without accurate materials data, finite element predictions can be meaningless. At NPL we have a wealth of knowledge regarding materials testing, enabling us to produce accurate materials property data for inclusion in FE analyses.

Prediction of moisture uptake in the adhesive layer of a lapjoint subject to water immersionTo optimise the output from finite element analyses, the relevant materials model must be used, along with accurate materials properties. Much of the modelling work within the adhesives area has concentrated on choice of materials models and accurate calculation of materials parameters to enable predictions of both deformation behaviour and stress/strain.

Types of adhesives studied include flexible and rubber-toughened adhesives, which require different materials models and data. NPL reports, measurement notes and Good Practice Guides have been produced on the modelling of adhesive materials.

Related Research

• Materials Models and Data for FE Analysis of Adhesives
• Data for Elastic-Plastic Materials Models
• Data for Hyperelastic Materials Models
• NPL Cavitation Model
• Creep Modelling of Adhesives
• Knowledge based design of plastics
• Adhesives Modelling publications

For more information: Louise Crocker