Stress-Function Variational Method for Accurate Free-Edge Interfacial Stress Analysis of Adhesively Bonded Single-Lap Joints and Single-Sided Joints

Large free-edge interfacial stresses induced in adhesively bonded joints (ABJs) are responsible for the commonly observed debonding failure in ABJs. Accurate and efficient stress analysis of ABJs is important to the design, structural optimization, and failure analysis of ABJs subjected to external mechanical and thermomechanical loads. This paper generalizes the high-efficiency semi-analytic stress-function variational methods developed by the authors for accurate free-edge interfacial stress analysis of ABJs of various geometrical configurations. Numerical results of the interfacial stresses of two types of common ABJs, i.e., adhesively bonded single-lap joints and adhesively single-sided joints, are demonstrated by using the present method, which are further validated by finite element analysis (FEA). The numerical procedure formulated in this study indicates that the present semi-analytic stress-function variational method can be conveniently implemented for accurate free-edge interfacial stress analysis of various type of ABJs by only slightly modifying the force boundary conditions. This method is applicable for strength analysis and structural design of broad ABJs made of multi-materials such as composite laminates, smart materials, etc.

Pressure-deformation relations of elasto-capillary drops (droploons) on capillaries

An increasing number of multi-phase systems exploit complex interfaces with interfacial stresses of multiple origins. Despite growing efforts, simple and reliable experimental characterisation of the interfacial properties remains a challenge,...

Interfacial Stresses of a Coated Square Hole Induced by a Remote Uniform Heat Flow

This paper presents an analytical solution of a coated square hole embedded in an isotropic infinite plate under a remote uniform heat flow. Based on conformal mapping, analytic continuation theorem and the alternation technique, temperature and stress functions are derived in a compact series form. Results of temperature contours and interfacial stresses are validated using the finite element method. The comparison indicates the high accuracy of the proposed method. Numerical results of both the interfacial normal and shear stresses for different properties and geometric parameters of a coated layer are provided in a graphical form. The results indicate that the interfacial stresses are highly dependent on the thermal expansion coefficient, thickness of the coating layer and shape factor of the coated square hole. In conclusion, the interfacial shear stresses exhibit a significant increase at the corners with abrupt geometrical changes, which would cause the delamination of the coating layer system. Furthermore, increasing the thickness of the coating layer and the shape factor results in a higher interfacial stress.

Comparison of elastic properties of different shaped particle reinforced composites using micromechanics and finite element method

In this work, differently shaped carbon nano-sized allotropes reinforced composite properties are estimated and interfacial stresses are calculated and compared to get the best carbon reinforcement. Carbon nanopowder, carbon nanotubes, nanographene and Buckminster fullerenes are selected as these materials have different shapes and reinforcement of these materials in the aluminium matrix will give different properties. The comparative studies are performed by using the Micromechanics and Finite element method. The longitudinal, transverse modulus, Poisson’s ratio are estimated along with the interface stresses between the constituents of carbon power/Al matrix composite, fullerene/Al matrix composite, CNT/Al matrix composite and graphene/Al matrix composite. From this work, it is found that the longitudinal modulus of the composite will be higher by using CNT or Graphene reinforcement and carbon particle or Buckminster fullerene reinforcement will give high transverse modulus than CNT and graphene reinforcement. The interfacial stresses generated between the reinforcement and the Aluminum matrix will be less by using carbon nanopowder than the other allotropes consider for the studies. This work will give an idea of the selection of nanoreinforcement of composite material in the perspective of elastic properties and interfacial stresses.