Maximum Tensile Load Research Articles

Comparative Study on Mechanical Joints of Aluminum Vibration Damping Sheet and 1.5 GPa HPF Steel sheet

In this study, the mechanical properties of aluminum vibration damping sheet and 1.5 GPa HPF steel sheet (SABC1470) dissimilar joining were evaluated. Joint methods of self piercing rivet (SPR), bolt/nut, flow drill screw (FDS), and blind rivet were compared to evaluate joint characteristic. In SPR Joining, buckling failure was occurred in SPR rivet caused by the strength of the 1.5 GPa HPF steel. So that, SPR hybrid joining was selected with a Al5052 alloy additional plate in lower sheet for formability and pre-hole processed on 1.5 GPa HPF steel in upper sheet. Through optimized of SPR die, the tensile shear load of the SPR hybrid joining was measured 7.53 kN. In FDS joining, failure of fastener was occurred due to the high strength of the 1.5 GPa HPF steel. FDS joining was available after pre-hole process on the 1.5 GPa HPF steel. However, delamination of the aluminum damping plate was observed and the tensile shear load was measured 3.14 kN. In bolt/nut joining, tensile shear load was measured depending on process variable (combination of plate, washer and tightening torque) and maximum tensile load was measured 5.43 kN. In blind rivet joining, the maximum tensile shear load was measured 3.64 kN, when the Al vibration damping sheet was placed on the upper plate. The large area of the blind rivet head released the concentration of stress on Al vibration damping sheet. As a result, SPR hybrid joining is considerable method because pre-hole processing is minimized and tensile shear load is higher than the other method.

Micromechanical approach to viscoelastic stress analysis of a pin-loaded hole in unidirectional laminated PMC

This paper aims to investigate the effect of viscoelastic behavior of polymer matrix of unidirectional fiber-reinforced laminated composite on stress distribution around the pin-loaded hole under tensile loading. The Laplace transform is used to prevent the integral form of matrix governing stress-strain relation. Applying a micromechanical model, all equilibrium equations for the fibers are written analytically in the Laplace domain. The numerical algorithm of Gaver–Stehfest is implemented, and the governing equations were solved at any given time to extract the concerned results in the time domain. The obtained results are validated against the Finite Element Method results obtained through ANSYS software. Moreover, a comparison of the results of this study at the time equal zero with elastic solutions of other references showed a good agreement. The results revealed that in the long term, the maximum tensile load in the intact fiber around the pinhole was enlarged and the tensile load in fibers far from the pinhole slightly was decreased. Moreover, the location of the maximum axial load that had occurred on pinhole edges was moved slightly toward the center over time.

Dissimilar laser welding of copper and aluminum alloys in multilayer configuration for battery applications

The joining process of copper and aluminum has become a key topic especially in the field of electro-mobility due to the fact that batteries, based especially on pouch Li-ion cells, are often manufactured in a way that involves joining together copper and aluminum tabs that constitute the anode and the cathode. Car manufacturers, in order to create more compact and performing batteries, are looking to stack more cells in small spaces and then weld the copper and aluminum tabs in multilayer configuration. However, welding those materials poses several challenges due to their differences in chemical and physical properties, such as melting temperature, thermal conductivity, and thermal expansion coefficient. One of the main challenges is represented by the formation of hard and brittle intermetallic compounds, which reduce both mechanical and electrical properties. The present paper addresses dissimilar laser welding of copper and aluminum in multilayer configuration by means of an infrared laser source equipped with galvanometric scanner optics, which allows us to obtain a spatial beam oscillation (circular wobbling) of the beam. The results confirmed that a larger wobbling amplitude does not enhance the properties of the connection. A maximum tensile load of about 1000 N and low electrical contact resistance were obtained with optimized parameters, while the presence of harder and brittle intermetallic compounds was reduced. Scanning electron microscope-energy dispersive x-ray spectrometer analysis confirmed the results obtained with the metallographic and mechanical tests.

Tensile behavior of FRP bar butt joints built with new FRP sleeves

This paper reports a comprehensive investigation on the tensile behavior of FRP bar butt joints built with new FRP sleeves. The simplified bond-slip constitutive relationship between FRP bars and bonding medium was firstly established by using the existing research results. Based on five proposed assumptions, the stress–strain analysis of the FRP bar butt joint was performed on the FRP bar, bonding medium and sleeve under tensile load. The bond-slip behavior and the shear force between FRP bars and bonding medium were discussed in detail. According to the stress–strain analysis, the key design parameters of the FRP sleeve and the anchor length of FRP bars were determined, which is also verified by comparing test data. According to the design parameter and anchor length, two types of FRP sleeves with two different internal structures and lengths were designed, and then these FRP sleeves were made of GFRP by professional manufacturers. In addition, the axial tensile tests were conducted on a total of 10 BFRP bar butt joints, GFRP bar butt joints and CFRP bar butt joints which are connected by the proposed GFRP sleeves. Based on the test results, the failure modes of various FRP bar butt joints built with GFRP sleeves were observed, and the corresponding tensile load–displacement curves, maximum tensile load and strain were analyzed. Finally, it is found that all fractures occur on the connected FRP bars instead of the GFRP sleeves, which indicates that various FRP bars can be effectively connected by the two types of GFRP sleeves. The load–displacement curves of the GFRP sleeves exhibit a small linear elastic deformation before the FRP bars rupture. The maximum elongated length of the GFRP sleeves is only 13% of the maximum tensile displacement of FRP bar butt joints uner tensile load, while the maximum circumferential strain of GFRP sleeves is about 41.72% of their corresponding longitudinal strain.

Effect of Rotational Speed, and Dwell Time on the Mechanical Properties and Microstructure of Dissimilar AA5754 and AA7075-T651 Aluminum Sheet Alloys by Friction Stir Spot Welding

In the current study, the effects of dwell time and rotation speed on the mechanical properties and microstructure of friction stir spot welded joints of dissimilar aluminum sheet alloys were investigated. Aluminum AA5754 and AA7075-T651 alloys were selected as the work piece. The joint quality, microstructural evolution and mechanical behavior of the welded regions were considerably affected by the welding parameters. The results obtained that rotation speed and dwell time play an important role on welding quality of aluminum sheet. The microstructure images showed the dwell time and rotation speed has great effects on pin penetration and hook deformation. Maximum tensile shear load 806.3 N was produced at 1000 rpm and 2 s dwell time, while the tensile shear load reduced around 25 % with longer dwell time 5 s and high rotation speed 1400 rpm. Moreover, the welding joint microhardness was improved by the decrease of dwell time and increase of rotation speed.

Characteristics of ultrasonic spot welding of Cu/Ni dissimilar metals

ABSTRACT With increasing clamping pressure, the bond density increases, the effective thickness decreases, and the plastic deformation at the Cu side near the welding interface regions below the sonotrode tip peak and valley increases; the maximum lap shear tensile load is obtained at the clamping pressure of 0.5 MPa. In the case of the Cu/Ni joint prepared at the clamping pressure of 0.5 MPa, evident mutual diffusion and nanoscale wave-like pattern appear in the Cu/Ni interfacial area, bonding between Cu and Ni sheets is formed by the interdiffusion of the parent elements. Plastic strain distribution and temperature on weld cross-section were simulated employing finite element analysis.

Comparative Analysis of Molded and Drilled Holes in Jute Fiber Reinforced Plastic Laminates

ABSTRACT Natural Fiber Reinforced Composites (NFRCs) are an important class of materials that have the potential to facilitate the global goals of sustainability and environment protection. In order to fully realize the potential of these materials, it is important to ascertain their good quality and cost-effective manufacturing. Although the primary manufacturing techniques for fabricating the products based on NFRCs are well developed, their secondary manufacturing in terms of machining and joining still requires extensive research efforts. Drilling induced damage is the major cause of rejection of composite products with holes. In the current experimental investigation, the efficacy of producing the holes during the molding stage has been investigated. The mechanical performance of the molded holes has been compared with the drilled holes in jute fiber reinforced epoxy/polyester composite laminates, in terms of open hole, filled hole, and bearing tests. The values of the maximum tensile load recorded during the tests have been compared and it has been found that the molded holes perform better than the drilled holes for both types of materials (jute/epoxy, jute/polyester). Also, the load extension curves suggest that the molded holes undergo larger extension as compared to the drilled holes.

Effects of Al-Si Coating on Static and Dynamic Strength of Spot-Welded Hot-Stamping Steel Joints

Al-Si is the most popular coating used to prevent oxidation on the surfaces of hot-stamped steel sheets during the heating process. However, like other coatings, it affects the strength of the spot welds in joining the hot-stamped steel parts. In this study, the effects of Al-Si coating on the tensile strength of the resistance spot-welded joints in hot-stamped steel are discussed. Two types of 1.8 mm hot-stamped steel, in uncoated and Al-Si coated forms, were resistance spot-welded, and the tensile shear behavior of the welded joints was studied in both static and dynamic tests. To do this, a special fixture for impact tensile shear tests was designed and fabricated. In the case of the Al-Si coated steel, the presence of the molten Al-Si over the fusion zone, especially its aggregation in the edge of the weld nugget, caused a decrease in the maximum tensile load capacity and a failure of energy absorption in static and dynamic tests, respectively. Additionally, it increased the probability of changing its failure mode from pull out to interfacial fracture in the dynamic test. This study shows that the tensile strength behavior of the welded joints for the Al-Si coated hot-stamped steel is lower than the uncoated steel during static, and especially dynamic, force.

The experimental study of CFRP interlayer of dissimilar joint AA7075-T651/Ti-6Al-4V alloys by friction stir spot welding on mechanical and microstructural properties

AbstractThe present study focused on two dissimilar metal alloys: AA7075-T651 and Ti-6Al-4V alloys with additional carbon fiber-reinforced polymer (CFRP) as an interlayer were welded together by friction stir spot welding (FSSW). The effect of welding parameters (rotational speed and dwell time) and carbon fiber-reinforced polymer on mechanical and microstructural properties of a weld joint was investigated. The obtained results explore the parametric effects on mechanical properties of the weld joint. The maximum tensile shear load 2597.8 N was achieved at the rotational speed of 2,000 rpm and dwell time of 10 s. While at the same rotational speed, 54.7% reduction in the tensile shear load was attained at shorter dwell time of 5 s. Therefore, dwell time plays an important role in the tensile shear load of a weld joint. The scanning electron microscope (SEM-EDS) results show the formation of intermetallic compound of Ti3Al and Ti-Al-C that significantly affect the mechanical and microstructural properties of the weld joint. Moreover, the effect of the rotational speed on micro-hardness was found at significant than dwell time. The micro-hardness of the weld joint increase by 18.90% in the keyhole rather than the stir zone and the thermomechanical affected zone, which might be due to the presence of ternary (Ti-Al-C) intermetallic compound.

Joint Properties of Aluminum Alloy and Galvanized Steel by AC Pulse MIG Braze Welding

In response to global environment and fuel efficiency regulations aiming to reduce CO2 emissions, multi-material structures that use lightweight materials are currently being developed to realize the weight reduction of vehicles in automotive manufacturing. The dissimilar welding of aluminum alloy to steel has great importance, but it is still challenging due to their widely varying thermo-physical properties and the formation of intermetallic compounds. This study aimed to investigate the effect of process parameters on the wettability, mechanical properties, and microstructure in AC Pulse MIG welded joints of AA6061-T6 and galvanized steel sheets. A parametric study on torch aiming position and welding current with EN ratio variation was performed to optimize the process parameters. The result showed that the amount of metal deposition increased with EN ratio. When the EN ratio was higher, the wire feeding speed increased and the heat input process lowered. Moreover, the wetting length increased, ranging from 6.6 to 8.4 mm, and the wetting angle increased from 31.2 to 67.6°, respectively. As a result of the tensile shear test, the maximum tensile shear load of dissimilar welded joints produced at 70 A with a 20% EN ratio was approximately 8.8 kN. From the result of scanning electron microscopy with energy-dispersive spectrometry, FeAl3 IMC was observed at the joint interface, and the IMC layer thickness decreased with EN ratio at 70 A.

Retention of a telescopic overdenture on customized abutments after the simulation of 1 year in function.

Telescopic implant-retained overdentures are considered one of the most common treatment modalities for edentulous patients. The aim of the study was to evaluate the retention of a BioHPP (biocompatible highperformance polymer) telescopic overdenture supported by customized abutments made from 2 different materials after the simulation of 1 year in function. Twelve models of a completely edentulous mandible were three-dimensionally (3D)-printed. Two implants and 2 groups of customized abutments - group Bio: BioHPP (n = 6) and group Ti: titanium (n = 6) - were used to support BioHPP telescopic overdentures. A vertically dislodging force was applied to each denture until its separation before and after 240,000 cycles of chewing simulation and 1,440 iterations of cyclic dislodgement for the simulation of 1 year in function in order to measure maximum tensile loads needed to dislodge the overdenture. Student's t test and the paired t test were used for the statistical analysis (α = 0.05). The initial and final retentive forces of the Ti group were significantly higher than in the case of the Bio group. A significant decrease in the retentive forces within the 2 groups after chewing simulation was observed and it was higher in group Ti; however, there was no statistically significant difference between the 2 groups. The retentive force values for implant-retained telescopic overdentures significantly decreased after the simulation of 1 year of overdenture use. Both BioHPP and titanium are considered suitable abutment materials to retain telescopic overdentures.

Effects of Processing Variables on the Mechanical Behavior of Thermoplastic Polypropylene/Glass Composite Reinforced with Weft-knitted Fabric with Various Layups

In this study, the tensile and bending properties of thermoplastic composites reinforced with weft-knitted fabrics have been investigated in various production conditions. The hot-pressing method was performed to produce the composites samples from Co-mingled polypropylene/glass weft-knitted fabric, which manufactured using the side-by-side polypropylene and glass yarns. The effects of heating time, cooling rate, and processing temperature as the processing variables parameters and the composites variables such as weight fraction of fiber and layup on mechanical behaviors were investigated. One-way ANOVA test was performed to analyze some data statistically. The rate of cooling has a significant effect on the composites’ mechanical behaviors. With increasing the cooling rate, the maximum tensile load, stress at samples’ failure, and maximum bending load increased by about more than 30 %, 105 %, and 233 %, respectively. The maximum tensile load of samples in the wale direction was more than that in the course direction. The maximum tensile load of samples with a weight fraction of 44 % was about 93 % higher than that with the 22 wt.%. The optimum values of processing variables to achieve the best mechanical performance of samples were the temperature of 200 °C, 6 minutes of heating time, and the faster cooling rate.

Multiaxial deformation behavior of aluminum alloy 6061 subjected to fire damage

Aluminum alloy AA6061 is of interest to the US Navy for ship structure applications due to its light weight, ease of manufacturing, corrosion resistance and strength. However, response to complex loading subsequent to fire damage presents a concern for practical applications. The purpose of this study is to evaluate the effect of fire damage on the microstructure and material response of AA6061 with applied tensile, torsional, and combined loading. Fire exposure was simulated in a controlled environment and testing under multi-axial loading conditions was carried out on virgin and fire damaged samples to evaluate mechanical response. Because of the non-circular sample cross-section, a three-dimensional digital image correlation technique was used to capture the evolution of local strains over the gage length of a deforming specimen subjected to tensile and/or torsional loading. Additionally, microstructure was investigated by electron backscatter diffraction at target cross-section locations subsequent to fire exposure and/or mechanical testing. Results indicate a 60–70% strength reduction with fire exposure. Fire exposed samples achieved higher maximum tensile load during combined loading compared to pure tensile loading. Microstructure was relieved by fire exposure while mechanical loading reveals strain-induced grain refinement. With sample geometry leading to stress concentrations, a deviation from yield values predicted by conventional yield criteria was observed; multi-axial stress-strain data can be of help in assessing the state of aluminum alloy structures after fire exposure.

Friction stir spot welding of AA5052 with additional carbon fiber-reinforced polymer composite interlayer

AbstractIn this study, similar aluminum alloys AA5052 with additional carbon fiber-reinforced polymer composite (CFRP) interlayer were selected to investigate the effect of welding parameters (rotational speed and dwell time) on the mechanical properties, joint efficiency, and microstructure of friction stir spot weld joint. The maximum tensile shear load was 1779.6 N with joint efficiency of 14.6% obtained at rotational speed of 2,000 rpm and 2 s dwell time, which is 39.5% higher than the value at low rotational speed 850 rpm and 2 s dwell time. Meanwhile, the maximum microhardness 58 HV was attained in the keyhole region at rotational speed of 2,000 rpm and dwell time of 5 s, which is 22.4% higher compared to low rotational speed. The SEM-EDS results reveal the presence of intermetallic compounds (Al–Mg–C), which enhance the intermetallic bonding between elements.

Preparation and biological characteristics of a bovine acellular tendon fiber material.

Acellular tendon matrix is an ideal substitute for constructing tissue engineering ligaments, but using detergents causes damage to collagen and fibrin during the process of decellularization. In this study, fresh tendons were lyophilized and separated into fresh tendon fiber (FTF) bundles, and then the cellular components in FTF were removed to prepare acellular tendon fiber (ATF) without adding chemical detergent. H&E staining and DAPI fluorescence microscopy showed no nucleus and DNA residue. Compared with FTFs, the DNA content of ATFs was significantly lower without the collagen content change before and after decellularization. The microstructure of collagen fibrils in ATFs was intact under scanning electron microscopy (SEM), and the maximum tensile load and elastic modulus between FTFs and ATFs were not statistically different. The ATF bundles were cultured with SD rat tenocytes for 72 hr and cells attachment to fiber surfaces were observed under SEM. ATF bundles were then implanted into paraspinal muscles, and histological analysis showed fibroblast-like cells within the ATFs and was similar to the control group (fresh tendon autograft) in morphology. H&E staining showed that the number of lymphocytes and plasma cells in ATF was less than that in fresh tendon autograft. ATF bundles were twisted into linear fiber materials by hand, of which the maximum breaking strength was similar to silk with same diameter. These findings demonstrated that ATFs retain their original fibril structure and mechanical properties after decellularization by trypsin and pancreatic deoxyribonuclease without detergent. Lyophilized ATFs linear fiber material provides the possibility of preparing personalized ligament and other tissue engineering scaffolds.

Characterization of Polypropylene Sheet Friction Stir Spot Welded Joint

A study to determine the effect of rotational speed and geometric shape of a tool on the mechanical properties of polypropylene joint using the FSSW technique has been carried out. A polypropylene sheet was cut into pieces with a dimension of 150 x 30 x 5 mm. A medium carbon steel bar was machined to fabricate welding tools. Two types of devices with shoulder angles of 0° and 5° were prepared, while the other parametric geometries were the same. While the friction stir spot welding (FSSW) process has been carried out at variations of rotational speeds of 985, 1660, and 2350 rpm, the other welding process parameters, such as tool plunge rate, dwell time, and delay time, were considered constant. The tensile shear load capacity, macrostructure, hardness, and failure mode of the joint results were then evaluated. The results revealed that using a pin tool with a shoulder angle of 5° achieved a maximum tensile shear load capacity at a rotational speed of 2350 rpm with a result of 2253 N due to its wider nugget area. The load capacity increased with the increase of rotational speed. A pin tool angle of 15° with a shoulder angle of 5° may be suggested for the tool’s chosen geometry.

Дослідження неметалевої композитної базальтової арматури періодичного профілю та перспективи її застосування

Дослідження неметалевої композитної базальтової арматури періодичного профілю та перспективи її застосування

Effects of welding parameters on tensile properties and fracture modes of resistance spot welded DP1200 steel

Abstract In this study, the maximum tensile shear load bearing capacity and fracture modes of resistance spot welded DP1200 steel were investigated, and the tensile shear properties of the joints were evaluated. The effects of different welding parameters on tensile shear properties, fracture modes, microstructure, microhardness, and heat affected zone softening were examined. Weld processes were performed by using 2 to 6 bar electrode pressure as well as 5 and 7 kA weld currents. The microstructure of resistance spot welded materials was evaluated, and the hardness profiles were determined. Experimental results showed that welding current and electrode pressure had a significant effect on the load-displacement characteristics of DP1200 welds. Three different fracture modes were observed in the tensile shear loads. It was also observed that the expulsion had a negative effect on the tensile shear properties.

The effect of Zn coating layer on the microstructure and mechanical properties of friction stir spot welded galvanized DP590 high-strength steel plates

Friction stir spot welding was successfully applied to the 1.4 mm thick galvanized DP590 dual-phase steel plates using a W-Re alloy rotating tool. During welding, a constant rotation speed of 800 rpm and a dwell time of 3 s were used and the tool penetration depth was ranged from 0 to 0.9 mm in order to study the flowing behavior and distribution of the Zn element in the joints. It was revealed that different forms of Zn were present along the interface. For example, there were Zn aggregates at the edge of the bonded interface, and there were droplet-like Zn particles along the partially bonded interface. Layers of accumulated Zn also existed outside the weld nugget. No obvious Zn element was detected inside the entire stir zone away from the interface. With the increase of penetration depth, the size of martensite in the stir zone increased from 8 to 14.2 μm. When the penetration depth was less than 0.6 mm, the shear tensile tests of the FSSW joints showed that the existence of Zn at the hook-like interfaces reduced the mechanical properties of the joints. However, when the penetration depth was larger than 0.6 mm, no noticeable effect of Zn was found for the joints with straight interfaces and a higher shear tensile load could be reached. The maximum shear tensile load was about 21.35 kN through the plug failure mode when a bonded interface of 1.9 mm was formed at a penetration depth of 0.8 mm.

Investigating the fatigue and mechanical behaviour of 3D printed woven and nonwoven continuous carbon fibre reinforced polymer (CFRP) composites

This paper evaluates the mechanical properties of woven continuous carbon fibre composites printed by additive manufacturing (AM). Comparison mechanical test studies (tensile, flexural and fatigue) were carried out with two nonwoven AM printed composites (unidirectional and multidirectional fibres), along with those of both a woven composite, as well as a composite reinforced using chopped carbon fibres. Compared with the 17 MPa tensile strength obtained for the chopped fibre composite, the average strength of unidirectional (nonwoven), multidirectional (nonwoven) and woven fibre composites were 39, 13 and 19-fold higher, respectively. The tensile strength of the woven composites was 52% lower than that attained by the unidirectional (nonwoven) fibre composites; and 38% higher than the multidirectional (nonwoven) fibre composites. A comparison was also made between the flexural and fatigue performance of the unidirectional (nonwoven) and woven fibre composites. The flexural strength of the latter was approximately 39% lower than the nonwoven composites, however, the load bearing capacity of woven fibre was superior. This performance difference was supported by the fatigue testing results. At 70% of maximum tensile load capacity after 2 × 105 cycles, the nonwoven composites failed, while the woven composites continued to perform until a level of 85% of maximum load capacity was reached. The superior fatigue strength of the AM fabricated woven carbon fibre composites, demonstrates their potential for use in high cyclic load applications.