T-peel Joints Research Articles

Locus of failure of T-peel joints formed between aluminium and various adhesives

Joints were made by bonding pretreated aluminium alloy L61 either a one-part epoxide, a two-part epoxide or a two-part polyurethane. The joints were then immersed in water at 60°C for periods up to 119 days before being broken in a T-peel test. After a phosphoric acid anodisation treatment the one-part epoxide and the polyurethane clearly failed cohesively within the adhesive. When viewed with a magnifying glass or a low powered microscope, the other systems (chromic acid etch/one-part epoxide, chromic acid etch/two part polyurethane, phosphoric acid anodisation/two-part epoxide) gave apparent interfacial failure. Auger electron spectroscopy was used to determine the true locus of failure. Three distinct failure modes were found, namely interfacial failure, cohesive failure within the adhesive and failure within the oxide.

Development of cohesive fatigue cracks in T-peel joints: Gilchrist, M.D. and Smith, R.A. Int J Adhesion and Adhesives (Jan. 1993) 13 (1), 53–57

Development of cohesive fatigue cracks in T-peel joints: Gilchrist, M.D. and Smith, R.A. Int J Adhesion and Adhesives (Jan. 1993) 13 (1), 53–57

Static Strength and Fatigue Performance of Aluminium-Adhesive T-Peel Joints

Numerical predictions of the tensile stresses within adhesively-bonded aluminium T-peel joints have established where critical fatigue defects are likely to initiate and propagate to fracture. These predictions of maximum stress correlate directly with static strength measurements of such joints. The results presented within this article elucidate the region of cohesive crack initiation, its subsequent direction of propagation and the relative duration of the different stages of fatigue crack growth. Separate stages of embedded, surface and through-width fatigue growth of cohesive defects with a T-peel joint are identified and compared. In this manner the fatigue life of typical bonded aluminium-epoxy T-peel joints has been established from the first stages of crack initiation to final joint fracture. It has been shown that joint static and fatigue strengths are maximized by having a maximum amount of adhesive within the fillet region of the joint.

Fatigue Growth of Cohesive Defects in T-Peel Joints

Abstract This paper uses 2D and 3D finite element models to predict the stresses within bonded and weld-bonded T-peel joints. Epoxy adhesive is modelled as a homogeneous layer providing a perfect bond between aluminium adherends. Knowledge of the critical tensile stresses enables the likely region of fatigue crack initiation to be predicted. The long term reliability and durability of a joint depend directly on its fatigue strength. This research elucidates the region of cohesive crack initiation, the subsequent direction of crack propagation and the relative duration of the different stages of fatigue crack growth. The various stages of embedded, surface and through-width fatigue growth of cohesive defects within a T-peel joint are compared. This establishes fatigue life from crack initiation to final joint fracture for typical bonded and weld-bonded T-peel joints.

Development of cohesive fatigue cracks in T-peel joints

This paper uses two- and three-dimensional finite element models to predict the stresses within bonded and weld-bonded T-peel joints. Epoxy adhesive is modelled as a homogeneous layer providing a perfect bond between aluminium adherends. Knowledge of the critical tensile stresses enables the likely region of fatigue crack initiation to be predicted. The long-term reliability and durability of a joint depend directly on its fatigue life. This research elucidates the region of cohesive crack initiation, the subsequent direction of crack propagation and the relative duration of the different stages of fatigue crack growth. The various stages of embedded, surface and through-width fatigue growth of cohesive defects within a T-peel joint are compared. This establishes fatigue life from crack initiation to final joint fracture for typical bonded T-peel joints.