Failure loads for model adhesive joints subjected to tension, compression or torsion

Strength, stability and size effects in the brittle behaviour of bonded joints under torsion: theory and experimental assessment

“…As a consequence a general formula to predict the brittle failure load for a tubular or non‐tubular bonded joint with or without tapered adherends can be obtained. This formula generalizes an analogous formula already presented in the literature 8 and experimentally validated for tubular bonded joints. The greater sensitivity to brittle collapse is emphasized for the non‐tubular geometry if it is compared with the tubular one (especially in the case of tapered adherends).…”

“…Equation (5) has been already presented and verified experimentally in the work by Gent and Yeoh 8 for tubular joints in the case of G 1 I 1 → ∞. In that paper a better estimate of the torsional moment, considering the frictional contribution to the work of detachment due to the shrinking of a tube subjected to torsion, is also presented.…”

“…Although this is intuitively obvious for beams (which typically are metallic), this is not the case for the adhesive, which is more likely to show a non‐linear behaviour. However, if the adhesive film is considered to be under torsion (tubular joint) and not subject to tension, the statistical theory of the rubber 8 shows how its behaviour can be considered to be substantially linear elastic. On the contrary, in the case of a non‐tubular joint, the stress state in the adhesive is basically normal.…”

“…A very general formula has been obtained by means of the Griffith 9 energy balance and applying linear elastic fracture mechanics 10–16 . It is supposed that the crack propagation at the interface between the two adherends takes place in the adhesive at the point of highest stress concentration in Mode I 8 . An energy balance is formulated for a small growth of the debonding: changes in the strain energy of the joint and in the potential energy of the loading device are equated to the characteristic energy needed for debonding.…”

Carbon nanotube dry adhesives with temperature-enhanced adhesion over a large temperature range

“…12). While the detailed derivation is given in Supplementary Equations 1–9 (Supplementary Discussions), equation (1) gives the enhancement factor at a specific temperature ( T ) as a function of the pull-out work associated with the asperities at T defined by l ( T ) and the fractional area of holes with CNT strand embedded in per unit area of surface, ϕ (where, ϕ = nπa 2 , ranging from 0 to 1, and there are n holes per unit area of the surface):18…”