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Highlights This paper presents an experimental examination of the compression demeanor of lightweight corrugated core composite (CCC) sandwich panel and corrugated core smart composites (CCSC) sandwich panels subjected to quasi‐static edgewise compression loading. The existence of shape memory alloy (SMA) wires and pre‐strain percentages of SMA are the indicators studied in this article. The fabrication procedure presented and the appraisement of the mechanical properties of the CCC and CCSC sandwich panels are expressed. The core geometry of samples is trapezoid corrugated made of aluminum. The facesheets are four layers of woven glass fiber/ epoxy laminated composite. For evaluation of the efficacy of the presence of SMA wires on mechanical specifications of sandwich panels, three SMA wires with various pre‐strain percentages (0%, 3%, and 6%) are embedded in each composite facesheet. Mechanical properties of all types of CCC and CCSC sandwich panels such as maximum force, critical damage force, specific strength, absorb energy, specific toughness, Young's modulus, and specific stiffness were evaluated. Results showed that the CCC sandwich panel has higher mechanical specifications than the CCSC sandwich panels with 0% and 3% pre‐strain. Also, increasing pre‐strained SMA wires improves all mechanical parameters of CCSC sandwich panels. CCSC sandwich panel with 6% pre‐strain has the highest compression properties than other sandwich panels. Maximum Force, Critical Damage Force, Specific Strength, Absorbed Energy, Specific Toughness, Young's Modulus, and Specific Stiffness of CCSC sandwich panel with 6% pre‐strain are 14.73 kN, 13.6 kN, 9.55 MPa/g, 26.61 kJ, 0.346 MJ/m3g, 4395 MPa and 0.61 kN/mm g, respectively. Lightweight CCC sandwich panel and CCSC sandwich panel manufactured. Compression behavior of CCC sandwich panel and CCSC sandwich panel evaluated. Pre‐strained SMA wires improves energy absorption of CCSC sandwich panels. Higher specific toughness was obtained with 6% pre‐strain SMA. Presence of SMA wires with no pre‐strain cannot improve the specific strength. [ABSTRACT FROM AUTHOR]

A 3D microvascular network which was generated by 3D printing method was within the composite specimens. Healing efficiency of the composites was investigated using mechanical tensile and creep tests. The experimental results revealed that despite mechanical properties degradation in the specimens due to the presence of the embedded network, significant healing efficiency can be obtained at both room and elevated temperatures by the presented healing method. The maximum healing efficiency of 89% was obtained in tensile strength for the specimens, which were healed for 7 days. Moreover, creep behavior of the self-healing specimens showed promising results and the healing efficiency was 83% in creep rupture time of the composites at 90 °C. [ABSTRACT FROM AUTHOR]

The response of laminated hybrid composite beam with embedded shape memory alloy wires subjected to impact of multiple masses is analytically investigated. Two degree of freedom spring-mass system and Fourier series are used in order to study the low velocity impact phenomenon on the resulting hybrid composite beam. A linearized contact law is chosen to calculate the contact force history. The effect of pseudo elasticity of wires as well as the recovery stresses generated in shape memory alloy wires due to shape memory effect is investigated. The beam is subjected to impactors with various masses, radii, and initial velocities. Impacts are occurred on the top and/or bottom surface of the beam. The effects of volume fraction of shape memory alloy wires, location of embedded wires, location of impacts and pre-strain in shape memory alloy wires on the contact force history and the deflection curve of the beam are investigated. The obtained results illustrated that embedding shape memory alloy wires in the laminated composite beam caused the deflection of the beam to occur more local at the points of impact, in comparison with the beams without shape memory alloy wires. Moreover, embedding 0.2 volume fraction of the shape memory alloy wires reduced the maximum deflection of the beam subjected to impact of 2 impactor masses by 57% and 3 impactor masses (on both sides) by 12%. Pre-straining the wires caused more reduction in deflection of the beam under impact loading. [ABSTRACT FROM AUTHOR]

The interfacial shear strength between the shape memory alloy (SMA) wire and epoxy matrix was evaluated experimentally using a single wire pull-out test. Moreover, the effect of pre-strain in SMA wires on the interfacial behavior was studied by pre-straining the SMA wires to 2% and 4% pre-strains. Experiments were conducted in both martensite and austenite phases of SMA. Results showed that pre-straining SMA wire in the martensite phase caused enhancement in interfacial shear strength due to recovery force generation. Further, 9.7% and 33% improvements in the interfacial shear strength were achieved at 2% and 4% of SMA pre-strain, respectively. However, the enhancement of interface behavior did not occur, when the SMA wires were subjected to pre-strain in the austenite phase. [ABSTRACT FROM PUBLISHER]

This article deals with the study of low velocity impact response on sandwich plates with functionally graded face sheets. High-order sandwich plate theory is improved by considering the in-plane stresses of the core that usually are ignored in the analysis of sandwich structures. A new approach is used to reduce the equations of motion from 27 equations to 15 equations and then solving them for both unsymmetric and symmetric sandwich plates. The model is also checked by finite element simulation and by comparing with other references for validation. A parametric study is done for various geometrical and mechanical properties. [ABSTRACT FROM PUBLISHER]

Using an improved higher-order sandwich panel theory (IHSAPT), the dynamic response of a sandwich beam with arbitrary cores (foam or functionally graded materials) subjected to single impact at arbitrary impacted face sheet and arbitrary locations is studied. The formulation uses the first-order shear deformation theory for the composite face sheets and a polynomial description of the displacements fields in the core, which is based on the displacement field of the second Frostig's model. The unknowns are the coefficients of these polynomials in addition to the displacements of the various face sheets. It is assumed that the impactor impacted normally and simultaneously over the top or bottom face sheets. The impact force between the impacted face sheet and the impactor is treated as the internal force of the system and in this study, for the first time, in order to simulate the impact phenomena, two models are presented: first, the linearized spring–mass model with two degrees of freedom (simply called TDOF), which can be solved by a new analytical method; second, the modified Hertz's model, which uses the perfect form of contact law (perfect model). An impact problem of sandwich beam is first solved and the results obtained from TDOF and perfect models are validated by comparing them with the analytical and numerical results published in the literature and also together. The agreement between the results is quite good. Then, the effect of various types of FGM function and its power and core to beam thickness ratio on the dynamic behavior of sandwich beam are studied. [ABSTRACT FROM AUTHOR]

Experimental investigation of repeated impacts on aluminium plates is performed using drop weights impacting from either constant or variable heights. In repeated impacts of constant and variable heights, the effect of plasticity is noticeable on the specimens in the very first impact. The effect of strain hardening is observed at higher impact numbers. Stiffness of plates is decreased by initiation and propagation of cracks in the specimens. Finally, perforation and penetration occur at the ultimate consecutive impacts. Numerical simulations of repeated impacts are also conducted using continuum damage mechanics by Abaqus software. Lemaitre's model is used as the damage model, and the code is written in Vumat subroutine. The effect of initial uniaxial and biaxial tensile stress on the plates is considered in repeated impacts, and it is concluded that plates with initial tensile uniaxial stress at transverse edges have maximum values of contact force and absorbed energy. [ABSTRACT FROM AUTHOR]

A new improved high-order theory is presented for global and local buckling analysis of sandwich plates with soft orthotropic core. Continuity conditions for transverse shear stresses at the interfaces as well as the conditions of zero transverse shear stresses on the upper and lower surfaces of plate are satisfied. Overall buckling loads, as well as wrinkling loads, are obtained for various sandwich plates. Effect of geometrical parameters and material properties of face sheets and core are studied on the overall buckling and face wrinkling of sandwich plates. [ABSTRACT FROM PUBLISHER]

The present investigation focuses on modifying the strength of single-lap adhesively bonded joints under tension–torsion loading with the use of three-dimensional finite element (FE) modeling. A single-lap adhesively bonded joint is reinforced by fibers and analyzed by means of ABAQUS-6.9.1 FE code. The adherends are considered to be made of orthotropic materials, while the adhesive is neat resin or reinforced by various types of fibers. The carbon and glass unidirectional fibers are used for adhesive reinforcement. In the FE modeling, the behavior of all the members is assumed to be linear elastic. The ultimate bond strength is increased as the fiber volume fraction in the adhesive is increased. By changing the properties and the behavior of the adhesive from neat resin (isotropic) to fiber composite adhesive (orthotropic) and with various fiber volume fractions and by changing the orientation of the fibers in the adhesive region with respect to the global axes, the bond strength in tension–torsion loadings are changed. Also, the excessive adhesive layer is modeled and its effect on the joint strength is investigated. [ABSTRACT FROM PUBLISHER]

Due to wide spread application of adhesive T-joints in various industries, a review of properties and strength of their fracture modes under static and dynamic loadings is required. By defining the ability of failure in the joint material and fracture of adhesive in the numerical model, fracture modes of sandwich T-joints have been investigated. This paper presents numerical results on the performance of sandwich T-joints subjected to static tensile, static transverse, and dynamic transverse loading. The results of available experiments in the literature have been used to validate the detailed numerical models capable of simulating the damage processes observed. In general, the failure load predicted by the finite element (FE) analysis is within 5% of the experimental results. [ABSTRACT FROM PUBLISHER]

The mechanical properties of adhesive joints are very sensitive to temperature and these types of joints which are subjected to high temperature, lose their strength. Therefore, the improvement of adhesive joints' thermal resistance is highly desired. In this study, creep phenomena in single-strap adhesive joints are considered and the effect of reinforcing the joints by shape memory alloy (SMA) on the creep behavior and the lifetime of the joints are studied experimentally. The effects of temperature and wires volume fraction on the joints creep behavior are also considered. For this purpose, several single-strap adhesive joints are reinforced by SMA in the shape of wires. The epoxy used in the adhesive joints is Araldite 2015 and NiTi shape memory wires with various volume fractions ranges from 0.5% to 2% are embedded into the adhesive. The creep tests are conducted at temperatures of 100 °C, 120 °C and 135 °C which all are above the glass transition temperature of the adhesive. By using SMA wires, a significant improvement in the adhesive joints creep properties could be achieved. [ABSTRACT FROM AUTHOR]

In this study, a high-order model for the analysis of circular cylindrical composite sandwich shells subjected to low-velocity impact loads is presented. The sandwich shell is composed of two composite face sheets and a transversely compliant core. The impact behavior of the cylindrical composite sandwich shells is described by a high-order sandwich shell theory. The interaction between the impactor body and the sandwich shell is approximated using a spring mass model. The present analysis is based on an iteration procedure, and yields analytic functions describing the contact force history. The contact force is considered to be distributed uniformly over a contact patch, the size of which depends on the magnitude of the impact load as well as the elastic properties and geometry of the impactor. Finally, the obtained results have been compared with the available experimental results, and a good correlation has been found. [ABSTRACT FROM PUBLISHER]

In order to reduce the maximum peel and shear stress concentrations in the adhesive layer, a smart adhesively bonded scarf joint system was developed by surface bonding of piezoelectric patches onto a typical scarf joint. The forces and bending moments at the edges of the developed smart joint system can be adaptively controlled by adjusting the applied electric field on the piezoelectric patches, thus reducing the peel and shear stresses concentration in the adhesive layer. In order to verify the effect of surface bonding of piezoelectric patches in smart scarf adhesive joints, an analytical model was developed to evaluate the shear stress distribution and to predict the peel stress. It was established that the piezoelectric patched joint could reduce the stress concentrations at the scarf joint edges. The influence of the electric field and the effects of the scarf angle and the adherend Young's modulus on the peel and shear stresses were investigated. It was found that the effect of scarf angle is more significant at higher angles to raise the stresses. The effect of the electric field on the shear stress is more significant than on the peel stress. [ABSTRACT FROM AUTHOR]

This study was intended to characterize the mechanical properties of nanoclay filled epoxy adhesive single lap joints under both static (tensile) and dynamic (impact) loadings. The nanoclay contents were 1, 3 and 5 wt% of epoxy resin (Araldite LY5052). The nanoclay particles were dispersed in the epoxy resin by a stirring device and then the mixture of resin and clay particles was subjected to sonication using an ultrasonicator. Glass/epoxy composite adherends were fabricated and used to study the behavior of epoxy adhesive bonded joints. The composite adherend surfaces were prepared according to ASTM D2093. According to ASTM D3165, the properties of the reinforced adhesive in shear were obtained by tension loading of single lap joint specimens. Also, the joints were subjected to in-plane and out-of-plane Charpy impact tests. The results showed that the adhesive joints with 1% nanoclay particles had the maximum strength in tensile loading and the highest values of Charpy impact energy were found for the joints with adhesives filled with 3% nanoclay particles. [ABSTRACT FROM AUTHOR]

In order to reduce the influence of the maximum peel and shear stress concentrations in the adhesive layer, a smart adhesively bonded single lap joint system was developed by surface bonding of piezoelectric patches onto a typical single lap joint. The forces and bending moments at the edges of the developed smart joint system can be adaptively controlled by adjusting the applied electric field in the piezoelectric patches, thus reducing the peel and shear stresses concentration effect in the adhesive layer. In order to verify the effect of surface bonding of piezoelectric patches in smart single lap adhesive joints, an analytical model based on shear lag assumptions was developed to evaluate the shear stress distribution and to predict the peel stress. For this purpose, the beam on elastic foundation (BOEF) approach in the adhesive layer was used. It was established that the piezoelectric patched joint could reduce the stress concentrations in the lap joint edges. The influence of electric field, location, and size of the piezoelectric patches in the single lap joint was also investigated. [ABSTRACT FROM AUTHOR]

Charpy impact tests were conducted on repaired notched aluminum specimens and the absorbed energy and fracture behavior of the specimens were investigated. The aluminum specimens contained a single-edge notch and were repaired with a metal sheet, composite, and fibre metal laminate (FML) hybrid composite patches on one of the side faces of the specimens. Some of the specimens were repaired on two sides. A metal sheet, laminated glass fibre reinforced polymer (GFRP), and carbon fibre reinforced polymer (CFRP) composite and FML patches with three and five layers were used to repair the aluminum specimens. The metal patches were made by phosphor-bronze, the composite patches were composed of woven glass and woven carbon fibre laminates, and the FML patches were fabricated from a combination of woven glass or woven carbon fibre laminates with phosphor-bronze metal sheet. The aluminum specimens had three different notch lengths. The results showed that the specimens repaired with FML patches of the same number of layers, irrespective of fibre type, absorbed almost the same energy level. The results also showed that the notched specimens repaired with single and double-sided FML patches with carbon fibre absorbed more energy than the other specimens. Generally, as the notch length increased, the absorbed energy by the notched aluminum specimen with or without any patch decreased. The effective role of patching in the repaired specimens was found to be substantial with the bigger notch lengths. [ABSTRACT FROM AUTHOR]

In this article, the response of rectangular smart hybrid composite plate subjected to low velocity impact is studied and the effect of some geometrical and material parameters on the response of the composite plate embedded with shape memory alloy (SMA) wires is investigated. The interaction between the impactor and the composite plate is considered in the impact analysis. The SMA wires are embedded within the layers of the composite laminate. The effect of the SMA wires on contact force history, deflection, in-plane strains and stresses of the structure was studied. The classical first-order shear deformation theory (FSDT) as well as the Fourier series method is utilized to solve the governing equations of the composite plate analytically. The interaction between the impactor and the plate is modeled with the help of two degrees-of-freedom system, consisting of springs-masses. The Choi's linearized Hertzian contact model is used in the impact analysis of the laminated hybrid composite plate. The simultaneous application of the FSDT, Fourier series method, springs-masses and Choi's linearized contact model helps to get a complete model and more accurate result and save computational time and effort for the analysis of the composite structures subjected to the transverse impact. The results indicated that some of the geometrical and material parameters like the volume fraction, the orientation and the through thickness location of the SMA wires, the longitudinal to transverse elastic modulus ratio of the plate and the material type of composite medium are some of the important factors affecting the impact process and the design of the structures. [ABSTRACT FROM AUTHOR]

In this study, the potential of superelastic shape memory alloy (SMA) wire to enhance the tensile strength of a glass fibers reinforced epoxy composite was evaluated. Composite specimens with one embedded SMA wire fabricated with hand‐layup method. The specimens were placed under tensile loading (pre‐tension) and unloaded before ultimate tensile strength. The pre‐tension amounts were 65, 75, and 85% of ultimate tensile strength. After unloading, SMA wire wants to transform to the austenite phase and recover its primary shape and a large amount of compressive stress will be released over the composite specimens. Results show that the ultimate tensile strength for specimen with 75% pre‐tension was 32% higher than the composite without pre‐tension. This pre‐tension has the best effect on ultimate tensile strength and pretension of specimens before ultimate tensile strength leads to higher tensile strength due to the high superelasticity of the SMA wires. POLYM. COMPOS., 39:E2454–E2459, 2018. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Impact is among the important loading scenario which is required to be addressed for fibre reinforced plastics (FRP) materials in ground or space vehicle applications. The failure behaviour of FRP materials under impact loading is a complex process and a detailed analysis of various mode of failure is necessary. In this paper the failure behaviour of laminated carbon fibre reinforced plastic (CFRP) composite structures under impact loading is investigated by conducting numerical simulations using the explicit finite element analysis ANSYS LS-DYNA software [1]. The impact responses and failure behaviours are being investigated by performing a parametric study and sensitivity analysis in which impact velocity, number of plies, incident angle, friction between contacted surfaces, impactor mass and the geometry are varied in separate cases. The FE model is validated by comparing the numerical results with other published results and good correlations are achieved. [ABSTRACT FROM AUTHOR]