Single Lap Composite Joints Research Papers (original) (raw)

In this study, a novel reinforcing method for glass-fiber reinforced composites, which consists of interadherend glass fibers (IAF) that get through the composite adherend like a pin, was investigated experimentally and numerically. Two types of joints were investigated. One is the traditional single lap joint without inter-adherend (Type A) and the other is Type B in which the fiber pin was used. Static tensile tests were performed at ambient environment in accordance with ASTM standards. In the numerical analysis, ANSYS 12.0 software package was used. The results show that the fibers improve the ultimate strength and damage tolerance of composite joints. In addition, the numerical results show a good agreement with the experimental ones.

- by and +1
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- Engineering, Mechanical Engineering, Composite Materials and Structures, FEA with ANSYS

Two-dimensional (plane-stress and plane-strain) theoretical models are presented for stress analysis of adhesively bonded single-lap composite joints subjected to either thermal or mechanical loading or a combination thereof. The joints consist of similar/dissimilar orthotropic or isotropic adherends and an isotropic adhesive interlayer. The governing differential equation of the problem is obtained using a variational method which minimizes the complementary strain energy in the bonded assembly. In this formulation, through-thickness variation of shear and peel stresses in the interlayer is considered. Both shear and normal tractionfree boundary conditions are exactly satisfied. Peel and shear stresses obtained from plane-strain analytical models considering a homogeneous adhesive interlayer are in close agreement with those of the finite element predictions. A systematic parametric study is also conducted to identify an ideal set of geometric and material parameters for the optimal design of single-lap composite joints.

- by Siddharth Tampi
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- Composites, Composite Materials, Adhesive, Single Lap Composite Joints

The composite structural members are highly used in the following applications such as aerospace, automobiles, marine, architecture etc., has attracted extensive attention in the past decades. A numerical and experimental study was carried out to identify the ultimate strength and failure modes of Bonded-single lap joints, Riveted-single lap joints and Hybrid-single lap joints at two different layers (3&4 Layer). In our project work, the effect of bonded, riveted, hybrid lap joints at different layer is analyzed in ANSYS and compared with the experimental test. ANSYA FEA tool has been utilized to investigate the stress distribution characteristics of a composite single lap joint under tensile loading. The experimental results are compared with FEA results using ANSYS. Our objective is to investigate the characteristics of failure modes and strength of composite single lap joints at two different layers with zero-degree fiber orientation using ANSYS.

Adherend surface treatment prior to bonding is pivotal for efficient assembly or repair of carbon fiber reinforced polymer (CFRP) composites. The effect of CFRP surface treatment has gathered much attention in the literature but reported test results on fatigue performance are less prevalent. The effect of surface treatment was extended in this work to cover the static and also fatigue strength of single-lap bonded joints. Surface treatments of manual sanding, grit blasting, and peel-ply plus grit blasting were produced and their surface roughness and energy were measured. The sanding treatment produced the lowest static strength but the best static strength retention at one million cycles with 55.4%, compared to 50.3% for peel-ply plus grit blasting, and 47.5% for grit blasting. The failure surfaces of the fatigued sanding specimens were the most uniform, mostly of cohesive failure mode for static and low-cycle fatigue, progressing to thin-layer cohesive for high-cycle fatigue.

- by Rene Roy
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- Composite Materials and Structures, Composites, Composite Materials, Surface Roughness

In this study, a novel reinforcing method for glass-fiber reinforced composites, which consists of inter-adherend glass fibers (IAF) that get through the composite adherend like a pin, was investigated experimentally and numerically. Two types of joints were investigated. One is the traditional single lap joint without inter-adherend (Type A) and the other is Type B in which the fiber pin was used. Static tensile tests were performed at ambient environment in accordance with ASTM standards. In the numerical analysis, ANSYS 12.0 software package was used. The results show that the fibers improve the ultimate strength and damage tolerance of composite joints. In addition, the numerical results show a good agreement with the experimental ones.

- by Volnei Tita and +1
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- Engineering, Mechanical Engineering, Composite Materials and Structures, Numerical Analysis

The present paper investigates experimentally and numerically the impact of a spherical water droplet onto a stationary sessile one lying onto a substrate. The experiments were performed with two different film thicknesses, three different We numbers and two surface contact angles (two substrates, aluminium and glass). For this purpose a CCD camera was used and the corresponding qualitative and quantitative characteristics regarding the time evolution of the phenomenon, such as the diameter and height of the evolving crown, were obtained by image analysis. The aforementioned investigation was extended applying also the V.O.F (Volume Of Fluid) numerical methodology for the prediction of the temporal evolution of the phenomenon, so as to identify important characteristics of the induced flow field, not easy to be measured. This permits the in depth understanding of the governing flow laws, which resemble to those in the case of a droplet impact onto shallow films. The governing Navier-Stokes equations are solved both for the gas and liquid phase coupled with an additional equation for the transport of the liquid interface. An unstructured numerical grid is used along with an adaptive local grid refinement technique, increasing the numerical accuracy along the liquid-gas interface with the minimum computational cost. The numerical model is validated against the corresponding experimental data showing a good agreement. The regimes of deposition and splashing are identified as a function of We number and of the maximum thickness of the steady film, which is affected by the surface wettability properties. Moreover, following an analysis of the controlling parameters describing the temporal evolution of the lamella spreading, the role of We and Oh numbers as also of the wetting contact angle were identified, providing analytical expressions for the main dimensions characterizing the phenomenon.

An innovative, hybrid joining technology (HYPER) is investigated. Metal-composite single lap coupons, reinforced with additively manufactured metallic pins, are subjected to high-cycle fatigue. A backface strain technique is used to identify damage initiation/growth and an ultrasonic inspection method is also used to help characterise failure. Fatigue life curves are generated and it is found that there is a discrete change in failure mode when load severity is reduced. High severity testing results in pin fracture above the pin root -similar to that observed during a previous static test programme. However, for high-cycle fatigue, at low loads, pins are torn from the adherend and cracks propagate through the stock material below the pin microstructure. It is proposed that this results from a change to the pin load mixity as joint rotation increases. Coupon failure is controlled and repeatable (for a given load severity) due to the sacrificial role of the pins and there is no significant damage to the composite adherend. Hence, it is believed that HYPER joints not only have excellent mechanical strength, compared to benchmark tests with bonded joints, but also offer greater potential for in-service repair than conventional, mechanically fastened joints.

The single adhesive joint has many applications in the shipbuilding industry, where it offers the advantage of joining materials (adherents) with different properties and characteristics using an adhesive. However, one disadvantage of this type of joint is the stress concentration at the ends of the joint, which directly affect the adhesive. Another disadvantage is the possible difference between the coefficients of thermal expansion of the adherents of the joint. Through compilation and classification of the formulas found in various publications, this study presents a state-of-the-art review of an adhesive single-lap joint that can be used in marine applications. It will consider the types of materials used as the adhesive and as the adherents, the possibility of varying the thicknesses of the adherents and the thickness of the adhesive, and the recommended design factors for each proposed methodology. This study proposes formulas to estimate the stresses for joints with balanced thicknesses and extrapolates the results for nonbalanced joints; also, an equation is derived to calculate the minimum overlap joint length for ship lengthening, allowing the design process to be simplified. The results are expected to facilitate the design of single-lap joints in marine applications, such as reinforcing composite panels and lengthening of hulls and superstructures.