Fiber reinforced polymer (FRP) composites, exhibit tremendous potential to supersede conventional materials in various manufacturing sectors due to their extra-ordinary properties. Nevertheless, a ...few obstacles hinder the application and promotion of FRP, among which poor connection performance is reviewed in this present paper. In order to overcome the shortcomings of traditional joining technology, hybrid (bonded/bolted) joining technology emergesprominently and becomes a hot research area with immerse engineering importance. Moreover, with the complexity of the design for hybrid joints (HJs), the finite element modeling (FEM) has become the main research method, which assists applications of HJs by systematic selection of parameters for efficient manufacturing. This review paper summarizes an up-to-date progress in FEM analysis for composite HJs, and it covers: modeling about numerical damage of HJs(consists of FRPs modeling, adhesive modeling and bolt modeling), simulation for manufacturing of HJs (consists of bonding technology, drilling process and installing fasteners) and simulation for the mechanical performance of HJs (including substrates geometry, adhesive parameters, multi-fasteners configuration, fastener-hole fit conditions and clamping force). Additionally, the existing numerical methods in literature are analyzed in detail followed by remarks on the current scope in the designing of HJs. This general review of simulation analysis methods for composite HJs not only helps to discover future research possibilities, but also provides an extensive guideline for new researchers to implement the simulation of HJs successfully and accurately.
Friction riveting has emerged out as a promising candidate for joining polymers to metals, since it is energy efficient, fast and eco-friendly without material wastage and pre and post processing and ...cleaning. For sustainable manufacturing of car ports, automobile panels and aircraft structures, there is a need for joining of polycarbonate to AA 6063 using friction riveting technique. Hence in the present work, Polycarbonate/AA 6063 combination is joined employing friction riveting with a new slotted end rivet. Microstructural examination reveals a visible deformation during the penetration of AA 6063 rivet that provides excellent anchoring. Decision tree is an exploration approach that is applied on friction riveting experimentation data and it has derived meaningful information out of testing data to reach the maximum possible tensile load carrying capacity by a friction riveted joint within the production constrains. The maximum tensile load of 5.75 kN can be achieved when rotational speed, friction time and depth of friction riveting are kept above at 2050 rpm, 37.5 sec and 9 mm respectively. It is helpful in industries during selection of different combination of process parameters to obtain the desirable joining strength.
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•Successful joining of dissimilar Polycarbonate to AA 6063.•Friction riveting with new slotted end rivet profile.•Decision tree approach, for judicial selection of processing conditions.•Micro-structural investigation on bonding mechanism at the interface.
Mechanical performance together with progressive failure process and failure modes of riveted, adhesively bonded and hybrid joints connecting CFRP and aluminum alloy with various overlap length were ...investigated. Experimental results showed that hybrid joints presented superior performance in terms of peak load and energy absorption, which increased by up to ~380%, 434% and ~19%, 56% respectively compared with solely riveted and bonded joints. Typical failure evolution photographs were taken with high speed camera for analyzing progressive failure process. Final failure modes of hybrid joints included rivet shear fracture, CFRP compressive deformation, adhesive failure, cohesive failure and light-fiber-tear failure.
•Hybrid joint exhibited two different stages in progressive failure process to prevent catastrophic failure.•Hybrid joints showed superior mechanical performance in terms of peak load and energy absorption.•Failure evolution photographs were recorded with high speed camera for detailed progressive failure analysis.•Various failure modes were analyzed regarding to three different joining methods.
This paper presents an experimental and numerical investigation in the static strength enhancement of composite laminate Single Lap bonded Joints (SLJ), reinforced by pins made of Uni-Directional ...(UD) fibre reinforced plastic composite materials. Bonded lap joint specimens were experimentally tested in tension to obtain the failure loads and failure modes. The specimens were subsequently benchmarked against the hybrid version of the joint resulted from the introduction of composite Pins. The Pin reinforcement enhanced the hybrid single lap joint strength by an average of 19.1% increase. Numerical models generated were used for correlation with the experimental results. Numerical and experimental results observation indicated that increased strength of the hybrid bonded/Pinned joint was partly attributed to the load sharing between the adhesive and the Pin past the adhesive failure initiation as well as to the enhanced out-of-plane bending stiffness after the Pin introduction on the lap joint. Numerical investigations were performed as well with hybrid SLJ reinforced by composite pins versus designs employing metallic Pins. The simulations showed that for the investigated lap joint design parameters, the hybrid metallic pin joint failed at a higher failure load. Nevertheless, the hybrid joint utilizing the composite Pin could benefit from the enhanced corrosion resistance properties. In the case of applying a larger composite Pin diameter and/or rearranging the fibre orientation in the Pin, the hybrid SLJs could potentially achieve higher strength characteristics before the adhesive bond ultimate failure in relation to the steel Pin, as well as resulting to additional weight saving up to 46.9%.
In the multi-material lightweight design of structural components for the automotive industry, the joint between different materials plays a significant role in reducing vehicle weight without ...compromising performance or safety. Conventional technologies to mechanically join metals and carbon fibre reinforced polymers result in either drilling a hole in the composite material or increasing the weight of the part because of the fasteners employed. This work presents a new, simple, cost-efficient and non-weight penalizing mechanical joining technology for metal sheets and fibre reinforced polymer prepregs. It consists of a single-step punching process where the metallic sheet is completely perforated, but the prepreg is not. The punch pushes the carbon fibres through the hole in the metal sheet with no or minimal fibre breakage, generating a mechanical interlock which, in turn, increases the shear strength and absorbed energy of the co-cured joint.
Hybrid joints have potential to improve the joint strength and efficiency compared to the bonded or bolted joint. Several studies have been performed to understand the influence of various design ...parameters on the hybrid joint strength. However, very few studies have been reported on the complex failure mechanism of the hybrid joint. In this study, a detailed analysis is carried out to understand the failure mechanism of the hybrid joint in Carbon fiber reinforced plastic (CFRP) laminate having 0/+45/90/−45s layup sequence under tensile loading both experimentally and numerically. Analysis of a simple bonded and bolted joint configurations are also included for comparison purposes. The acoustic emission (AE) technique is utilized for the damage assessment and the 3D digital image correlation (DIC) technique is used to capture the whole field strain around the bolt region. A detailed fractographic study using a digital optical microscope is also carried out to critically ascertain the presence of different damage modes. An in-house instrumented bolt is realized to measure the load transfer through it upon loading. A finite element based progressive damage model (PDM) along with the cohesive element is also developed to predict the damage evolution and failure mechanism for all the joint configurations.
•Tensile and cross tensile responses of CFRP/Al blind riveted-bonded hybrid joints were investigated.•Original defects of the joints with two different locking modes were observed through SEM.•Joints ...with locking mode of RC showed better mechanical properties in both tensile and cross tensile tests.•Developed FE models could replicate the adhesive failure behaviors and identify the damaged areas.
The application of riveted-bonded hybrid joints between dissimilar materials in vehicle structures has attracted increasing interest. This study aimed to investigate into the responses of blind riveted-bonded hybrid joints connecting carbon fiber reinforced plastic (CFRP) and aluminum alloy (Al) subjected to tensile and cross tensile loads. Joints with two different locking modes were fabricated, and their micro topographies were observed through scanning electron microscope (SEM). The experimental failure modes, force responses and mechanical properties of these joints were analyzed and compared, then numerical models were established for further exploring the failure mechanisms. The results showed that the imperfections of RC joint (CFRP placed on protruding head side) were fewer than that of RA joint (Al placed on protruding head side). RC joints showed superior mechanical properties. The energy absorption of RC joints was 14.20 % higher than that of RA joints in tensile tests. The peak force, failure displacement and energy absorption of RC joints were 21.67 %, 9.59 % and 44.48 % higher than those of RA joints in cross tensile tests, respectively. The simulation results were consistent with the experimental counterparts, with errors limited to 8 %. These numerical models can effectively replicate the failure behaviors and identify damaged areas of the specimens.
Hybrid reinforced concrete steel (RCS) frames consisting of reinforced concrete (RC) column and steel (S) are used frequently in practice for mid-to-high-rise buildings. RCS frames possess several ...advantages from structural, economical and construction view points compared to either traditional RC or steel frames. One of the key elements in RCS frames is the beam-to-column joint. This paper suggests a design method to evaluate the mechanical behaviour of a novel type of exterior RCS beam-column connection in which a steel profile totally encased into a RC column is used to connect the beam through the steelwork part of composite section. The proposed design model is developed considering experimental test results and finite element (FE) analyses. In the first part of the paper, an experimental investigation on the static behaviour of the hybrid joint is presented. Four full-scale specimens were tested under monotonic loading. The primary differences between the specimens are the concrete class and the anchorage length of the embedded steel profile in the RC column. The experimental results indicated that the overall behaviour of the specimens was significantly affected by the shear panel deformations of the embedded profile. Next, a finite element model was created. The FE model predictions compared favourably against experimental tests and confirmed the order of yielding/cracking of joint components. Finally a design method based on Eurocodes 2, 3 and 4 is proposed to determine the initial rotational stiffness and the bending resistance of the joint.
•Experimental tests on hybrid steel beam to RC column joints with encased steel profile.•Limited impact of long encased steel profile on mechanical characteristics.•Order of yielding/cracking of components evaluated experimentally and by finite elements.•An Eurocode model for the initial rotational stiffness and bending resistance.
Though aircraft joints conventionally employ either mechanical fastening or adhesive bonding, the hybrid bolted/bonded joint has recently appeared as an alternative with possible superior ...performance. A key aspect of the hybrid joint design is the load-sharing between the bolts and the bond, and performance can benefit from using a flexible adhesive. While the static properties of flexible epoxy adhesives are covered in the literature, the properties under cyclic loading are not fully understood. This study investigates the mechanical properties of flexible epoxy adhesives under cyclic loading and the corresponding effect on composite hybrid joints. This study is twofold. First, cyclic tensile tests on the bulk adhesive investigate the evolution of the adhesive stress/strain. The results show that the modulus and yield stress progressively decrease due to the accumulation of plastic deformation. As the load cycles continue, the stress/strain response converges limiting this accumulation. Subsequently, cyclic tension-tension tests are performed on hybrid joints. Attributed to the aforementioned behaviour of the adhesive properties, the bolt load-sharing is observed to progressively increase until a convergence is reached. This paper provides the understanding on the evolution of the mechanical properties of flexible adhesives under cyclic loading and further confirms their potential in hybrid joint applications.
Most studies usually use load-displacement curve or post-failure analysis to understand the mechanical behaviour of hybrid bonded-bolted (HBB) joints. While load sharing in HBB joints is the crucial ...design parameter and it is important to capture strain field changes or failures under real-time loading conditions. Therefore, two-dimensional digital image correlation (2D-DIC) technique is applied to experimentally investigate the behaviour of bonded and HBB composite joints under quasi-static tensile loading. A flexible epoxy paste adhesive is used. The bonded joint had a hole in the centre to determine the effect of the difference between the stress concentration due to the existence of the hole and the additional stress around a hole due to installation of the bolt. The strain fields around the bolt in a HBB joint and around the open hole in a bonded joint were compared accurately. The DIC technique was able to effectively and rapidly measure the strain field and identify the onset of failure around the fastener during the tests. Finally, the advantages and disadvantages of the DIC technique compared to the classical similar techniques for characterizing the composite joints are briefly explained.
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