Evaluating the localised through-thickness load transfer and damage initiation in a composite joint using digital image correlation

• Published in: Composites. Part A, Applied science and manufacturing Vol. 61; pp. 224 - 234
• Main Authors: Crammond, G., Boyd, S.W., Dulieu-Barton, J.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2014; Elsevier
• Subjects: Applied sciences; B. Adhesion; B. Stress concentration; D. Mechanical testing; D. Non-destructive testing; E. Joint/Joining; Exact sciences and technology; Forms of application and semi-finished materials; Laminates; Polymer industry, paints, wood; Technology of polymers; E. Joint/Joining; D. Mechanical testing; B. Stress concentration; B. Adhesion; D. Non-destructive testing; Laminate; Butt joint; Epoxy resin; Mechanical properties; Tensile property; Digital image; Experimental study; Mineral fiber; Double strap joint; Composite material; Deformation measurement; Through thickness property; Non destructive method; Adhesive joint; Glass fiber; Fracture mode
• ISSN: 1359-835X; 1878-5840
• DOI: 10.1016/j.compositesa.2014.03.002

Experimental analysis of the stresses and strains in a glass fibre polymer composite double butt strap joint using digital image correlation (DIC) is described in the paper. Initially the strain fields through the thickness of the joint are derived from DIC measurements, capturing the effect of the initiation and development of cracks in the joint up to failure. It is demonstrated that the relatively small strains developed in the through-thickness direction are critical in the development of damage in the joint at the geometric discontinuity between the adherends. An experimental methodology is established to perform DIC at the mesoscopic scale, enabling accurate, high spatial resolution analysis of the small through-thickness strains around the discontinuity. The DIC enables the strains to be evaluated, their development monitored and hence establish their contribution to the failure process. To determine the full-field stresses in the joint experimentally derived materials properties are used. From component stress maps principal stresses maps are derived, which clearly show where the damage is initiating and its subsequent growth in the composite adherends until final failure of the joint.