35 years of standardization and research on fracture of polymers, polymer composites and adhesives in ESIS TC4: Past achievements and future directions

Since its first meeting in 1985, ESIS TC4 has held regular semiannual meetings with between 15 and 35 participants, has organized a series of conferences (the first in 1994, then triennial since 1999) and has developed six ISO test standards on the fracture of polymers, polymer composites and adhesives with another two currently going through ISO standardization and ballots, and several more under development. The activities have also resulted in publications, including two books and two review papers. Initial activities focused on round robins providing test methods for determination of fracture properties for, e.g., technical data sheets, quality assurance, materials selection, or materials development and optimization and materials modelling. These procedures defined standard specimens, test rigs and test conditions. For polymers, standards for specific ranges of loading rate and for composites and adhesively bonded joints, procedures for different loading modes and mode mixes were developed. Recently, standard composite specimens with unidirectional fiber orientation were shown to overestimate the delamination resistance of multidirectional laminates under cyclic fatigue loading. First round robin data from the environmental stress cracking tests show the potential for discriminating between the different susceptibilities of polymers to environmentally induced fracture. Future activities will include elastomeric materials, simulation and modelling in combination with experiments or prediction of fracture behavior. Another topic of recent interest concerns digital tools, e.g., image analysis, automated data acquisition, data fitting and analysis. Guidelines on how to best reduce extrinsic scatter and eliminate human errors will improve the data quality.