Shear Punch Research Articles

Investigation of shear and tensile mechanical properties of ZK60 Mg alloy sheet processed by rolling and sheet extrusion

The microstructure, texture and mechanical behavior of two wrought ZK60 magnesium alloys were investigated by tensile test and shear punch test (SPT). The samples processed by hot rolling and the combination of hot rolling and sheet extrusion techniques. The mechanical properties of the alloys correlated to the microstructural characteristics and the texture. Microstructural analysis showed that extrusion transformed the equiaxed coarse grain structure of the rolled sample with an average grain size of 68 μm to a bimodal structure including very fine dynamically recrystallized (DRX) grains, having an average grain size of ∼2.8, and large elongated deformed grains. The sheet extrusion process improved the tensile yield stress, the ultimate tensile strength, the shear strength, and the tensile elongation to failure. The strength enhancement was attributed to the finer grain size and the change of the volume fraction of the secondary phase particles. It was demonstrated that extrusion could improve both strength and ductility at room temperature in wrought ZK60 alloy. Although the tensile ductility improved after extrusion, it was shown that deformability in SPT remains unchanged after extrusion. Microstructural observations show that in SPT the positive effect of the grain refinement on the ductility was compensated by the hindering effect of Mg4Zn7 particles on the glide of <c+a> pyramidal dislocations. This slip is a dominant mechanism of deformation during SPT due to the basal texture.

Effects of processing parameters on the fracture behaviour of cold roll bonded and accumulative roll bonded Al–Cu lamellar composites

Al–Cu composites were fabricated by cold roll bonding (CRB) and accumulative roll bonding (ARB) processes. The effects of different parameters were investigated on the failure mechanism of the composites. A scanning electron microscope (SEM) and an optical microscope (OM) were used to characterise the microstructures of the resulting composites. The peeled surfaces of the CRBed material revealed that micro-cracks were formed almost perpendicular to the rolling direction and caused the premature failure of the bonding during the peeling test. Also, tensile, microhardness and shear punch tests were conducted on the Al–Cu composites produced under different conditions. Failure analysis of the non-heat-treated composites revealed that the layers separated from the middle of ARBed specimens. However, these centre-line separations were alleviated in composites subjected to heat treatment, even though the initiation of inter-lamellar micro-cracks were observed due to the formation of intermetallic compounds for heat-treated specimens.

Characterization of piercing damage in CFRP cross-ply laminates after punch shear machining via impact loading

In industrial processes, piercing and trimming are essential because composite structures are usually manufactured in a near-net shape to reduce machining operations. Punching and shear cutting using out-of-plane shear loading are expected to increase productivity. Nevertheless, little is known about the effects of such operations on polymer-matrix composites. This study presents on the characterization of piercing damage in typical carbon fiber reinforced plastic (CFRP) cross-ply laminates [0°2/90°2]s after punching using quasi-static (QS) and drop-weight impact (DWI) loadings. During QS punching, the upper and lower ply interfaces delaminate due to the high shear stress to cut fibers and gradual shear deformation in the middle ply; however, during DWI punching at a low impact velocity, delamination of the lower ply interface can be reduced due to the localization of shear deformation, as compared to that in QS punching. Finally, the damage accumulation process during DWI punching is discussed.

Influence of high pressure torsion on microstructure evolution and mechanical properties of AZ80/SiC magnesium matrix composites

The effect of applying 1, 5 and 10 turns of high pressure torsion (HPT) as a severe plastic deformation technique on the microstructural evolution, hardness, tensile and shear strength of an as-cast AZ80-SiC magnesium matrix composite is investigated in the present study. The results show that HPT at room temperature refines the microstructure of the as-cast material having an average grain size of 176 ± 58.9 μm to a fine grain structure with average grain sizes of 4.2 ± 4.1 μm and 2.5 ± 2.1 μm in 5 and 10 turns HPT samples, respectively. In addition, ultra-fine grained regions (grain size <1 μm) with volume fractions of about 12, 27 and 31 vol% are obtained in the samples processed by 1, 5 and 10 turns of HPT, respectively. Based on microstructural observations, it is concluded that 5 and 10 turns HPT samples are almost similar in terms of grain size, recrystallized fraction, low-angle grain boundary fraction, and recovered parts. The ultimate tensile and shear (achieved from shear punch tests) strengths of the as-cast sample are improved by applying HPT due to grain size and texture hardening mechanisms. The highest strength values are obtained after performing the first HPT turn due to the more significant effect of texture hardening in comparison to the 5 and 10 turns HPT-processed samples. Similar to the strength results, the hardness of the as-cast material is also enhanced from 66 ± 6 HV to about 123 ± 3 HV through HPT processing.

The micro/macro mechanical approach of reinforced braid composite used in tribology

Self-lubricant composite is a flourish scope of technology that merits academic and industry attention, as it is a specific part which essentially employed in acute operation conditions. In the present study, the mechanical properties of the self-lubricating composite of two-dimensional (2D) and three-dimensional (3D) braid were investigated. The composites contained Polytetrafluoroethylene (PTFE) fibers as a lubricant and glass, carbon, and Kevlar as a reinforcement, hierarchically incorporated into the structure. In order to study the composite behavior as well as to determine the modulus and hardness of the sample, an indentation test, which is very similar in loading to abrasion tests, was applied. A microband test was also conducted to assess the adhesion between the resin and the PTFE fiber. Shear punch tests were performed to evaluate the total shear strength and impact test to estimate energy absorption and impact strength. The results showed that PTFE/epoxy matrix has poor adhesion. Composites with higher PTFE volume fraction had good energy absorption and, at the same time, low shear strength. The higher modulus of carbon composites was concerned.

Characterization of AA6111 aluminum alloy thin strips produced via the horizontal single belt casting process

ABSTRACT In this research, AA6111 aluminum alloy strips, 250 mm wide and ~6 mm thick, were produced via the horizontal single belt casting process. The strip microstructure was analyzed using optical and scanning electron microscopy, and the measured average grain size was 90 μm. This is significantly smaller than the average grain size of the products produced via direct chill (DC) casting route (i.e., 231 μm). An analysis of intermetallic compounds was also conducted using energy dispersive spectroscopy. These were observed to be distributed within and along the grain boundaries and are enriched in Mg, Si, and Cu. The shear punch test was performed to determine the ultimate tensile strength of the cast strip, which was observed to be 280 MPa. This value is significantly higher than the strength documented in the literature for DC cast products. A 3D profilometer was used to determine the top and bottom surface roughness of the as-cast AA6111 strips. The strip top surface was found to lie within 120 μm range, whilst the bottom surface roughness was less than 30 μm.

Effect of Mn addition on the microstructure, mechanical properties and corrosion resistance of a biodegradable Mg–Gd–Zn alloy

The effect of 0.5 and 1 wt% Mn additions on the microstructure, mechanical properties, and biocorrosion resistance of an extruded Mg–3Gd–1Zn (GZ31) alloy was investigated. Mn addition refined the grain structure so that the grain size decreased from 3.7 μm for the GZ31 alloy, to 2.3 μm for GZ31–1Mn alloy. Hardness measurements and shear punch tests (SPT) revealed that by adding 1 wt% Mn, the hardness, shear yield stress (SYS) and ultimate shear strength (USS) increased from 61 to 66 Hv, 102.0 to 128.5 MPa, and 142.8 to 152.4 MPa, respectively. The main mechanisms responsible for the improvement of mechanical properties were grain refinement and higher volume fraction of the second phase particles formed by Mn addition. Electrochemical impedance spectroscopy showed that the addition of 1 wt% Mn increased the overall corrosion resistance from about 515.4 Ω cm2 to 5883.6 Ω cm2. In addition, initiation of the inductive loop in the Nyquist diagrams of the Mn-containing alloys, in the lower frequencies in comparison to the base alloy, can be a sign of retarding the onset of pitting corrosion. The improved corrosion resistance of these alloys was due to the refined microstructure and formation of a more stable protective layer on the surface.

Crack growth properties in granite specimens consisting non-persistent joint under punch shear through test

Experimental and numerical methods were used to investigate the effect of echelon notchs on the shear behaviour of joint’s bridge area in granite. A punch-through shear test was used to model the granite cracks under shear loading. Granite samples with dimension of 20 mm×150 mm×40 mm were prepared in the laboratory. Within the specimen model and near the edges, four edge notches were provided. Nine different configuration systems were prepared for notches. In these configurations, the length of each notch was taken as 3 cm, 4cm and 5 cm. Assuming a plane strain condition, special rectangular models were prepared with dimensions of 100 mm×100 mm using particle flow code in two dimensions. similar to those for joints configuration systems in the experimental tests i.e. 9 models with different rock bridge lengths and rock bridge joint angle were prepared. The axial load was applied to the punch through the central portion of the model. This testing showed that the failure process was mostly governed by the rock bridge length and rock bridge angle. The shear strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the shear behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the rock bridge angle. The strength of samples decreases by increasing the joint length. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.

Punch shear test for quantitative evaluation of bone defect repair in Wistar rat tibia

IntroductionBone healing is a complex process influenced by biological and mechanical factors that restores the injured bone's load bearing function. Qualitative methods are usually employed to assess this repair process. This study presents a method of quantitative evaluation of bone repair in circular defects produced in the medial proximal metaphysis of the tibia of rats by means of punch shear tests (PST). ObjectiveTo describe and test a mechanical punch shear test designed to quantify over time the regeneration of bone defects produced in Wistar rats’ tibiae. Material and methodsIn seven experimental groups, 3.2 mm in diameter and 1.5 mm deep defects were drilled on the medial surface of both proximal tibial metaphyses of the animals, just below the joint surfaces. The animals of an additional group were maintained with intact tibiae. After one, two, three, four, six, eight and 12 weeks of follow-up, the animals were sacrificed and the tibiae removed. After removing the soft tissue, the tibial proximal metaphyses were embedded in epoxy resin and cut with a diamond cutting blade, in order to obtain bone slices with equal thickness. The PST were carried out in a universal testing machine and the maximum shear forces were measured. ResultsThe forces increased as a function of the follow-up time in the period of one to three weeks (p <0.001); from this follow-up time on, there were no statistical significant differences between the groups, including the intact tibiae. ConclusionThe test method proved to be suitable to quantitatively assess bone regeneration in monocortical defects produced in the proximal metaphysis of rat tibia within one and three weeks after defect production.

Local formability assessment of AHSS steels with shear cut tensile tests

As an alternative to the ISO16630 hole expansion test, the punched tensile test is increasingly popular for edge crack characterization of AHSS advanced high strength steels. In this investigation the reduction of area as well as thickness reduction at fracture in the vicinity of left/right sample edge fracture sides has been determined by means of light optical microscopy according to the Hance local formability test methodology for 10% to 40% cutting clearance in (both sided) sheared cut vs. spark eroded or milled edge conditions. An edge crack index has been defined based on the tensile sample fracture shape. Local formability tensile properties based on area reduction or average thickness reduction are more sensitive to edge condition than Axx fracture elongation values. The determination of the reduction of area at fracture is however challenging due to projection issues. The % thickness reduction at minimum thickness as well as at left/right thickness in cut edge vicinity may offer some additional information about edge crack initiation and final fracture. The shear punch edge quality (punch and die tool wear, target vs. actual clearance) should be closely monitored for accurate reproducible testing results.

Microstructure, texture, and mechanical properties of the extruded and multi-directionally forged Mg–xGd alloys

The microstructural and textural evolutions as well as room-temperature mechanical properties of three binary Mg–Gd alloys with 1, 2, and 3 wt% of Gd were studied in the as-extruded condition and after two, four, and six passes of multi-directional forging (MDF). Microstructural observations of the extruded samples were indicative of partial dynamic recrystallization resulting in bimodal grain structures comprised of elongated un-recrystallized patches and fine recrystallized grains. After six passes of the MDF process, the fraction of the un-recrystallized regions decreased because of dynamic recrystallization, and thus, relatively uniform microstructures were achieved in all alloys. The greater fraction of the un-recrystallized patches and the finer grains in the recrystallized regions of the Mg–3Gd alloy confirmed the more pronounced retardation of recrystallization via solute drag mechanism at the higher Gd concentrations. Evaluation of crystallographic texture revealed that by applying the MDF process, the conventional fiber texture of the extruded condition was replaced with a new randomized texture, in which the basal planes had a tendency to rotate at angles of lower than 90° to the transverse direction. Mechanical properties were evaluated using shear punch testing (SPT) and the results showed that with increasing the number of MDF passes in each alloy, the achieved finer grain structure was responsible for improving the shear strength. In addition, increasing the Gd content of the alloys resulted in finer grain size, more solute atoms, and higher fraction of Mg 5 Gd second phase particles, all of which led to the enhancement in shear strength.

Evaluation of the Mechanical Properties of Precipitation-Hardened Martensitic Steel 17-4PH using Small and Shear Punch Testing

Evaluation of the Mechanical Properties of Precipitation-Hardened Martensitic Steel 17-4PH using Small and Shear Punch Testing

High temperature effect on quasi-static and low velocity impact behaviors of advanced composite materials

In this study, the effect of ambient temperatures on the punch shear and low-velocity impact behavior of S2 glass fabric and carbon-kevlar hybrid fabric reinforced epoxy composites was investigated. The quasi-static tests (QST) were performed by using a Universal Shimadzu Tensile Testing Machine with various crosshead speeds. Low-velocity impact (LVI) tests were also carried out by using the CEAST Fractovis Plus impact test machine at different impact energies. Flat-nose impactors with a cylindrical punch diameter of 12.70 mm were mounted to the test machines. Both tests have been carried out at various temperatures. After the experiments, the load-displacement, the absorbed energy-impact energy/crosshead speed and punch shear strength graphs are plotted. From the obtained results it can be said that, in penetration cases of low-velocity impact and quasi-static tests, absorbed energy and punch shear strength values show similar behavior for hybrid carbon-kevlar/epoxy at each temperature except for 80 °C while these values are different from each other for S2 glass/epoxy at all temperatures.

Insight into the effect of weld pitch on the microstructure-properties relationships of St 37/AISI 316 steels dissimilar welds processed by friction stir welding

This research aims to evaluate the effect of weld pitch on the microstructure and properties of St 37/AISI 316 steels friction stir welds. The microstructure and microtexture of the samples were studied by means of electron backscatter diffraction analysis. The mechanical behaviors of the weldments were also investigated by microhardness, shear punch testing, and uniaxial tensile testing. In addition, the corrosion behavior of the welds was also evaluated. It was observed that the weld pitch of 0.0830 or 0.0625 mm/rotation resulted in producing defect-free welds with acceptable tensile strength level. Moreover, hardness and shear strength of the weld zone were improved up to 57% and 74%, respectively as compared to the base metals. It was due to the grain refinement which occurred within the stir zones by activating the dynamic recrystallization mechanism. Initial texture components of the base metals were replaced by recrystallized texture components in the stir zones. Orientation of grains in the stir zones was found to be highly dependent on the weld pitch. Regarding the corrosion resistance, the obtained results revealed that stir zone of St 37 steel was the weakest part of the weldments. Overall, the weldment employing the weld pitch of 0.0625 mm/rotation was found to achieve superior microstructural features and optimum properties.

Quasi-static penetration behavior of fiber-reinforced polypropylene and acrylonitrile butadiene styrene matrix composites

The quasi-static punch shear behaviors of thermoplastic composites with different polymer matrices and fiber types were investigated. This study was also focused on how much energy absorption capability can be increased by low fiber fractions. Maleic anhydride grafted polypropylene (MA-g-PP) and acrylonitrile butadiene styrene (MA-g-ABS) were used as the matrix material. One layer of aramid, carbon and glass fiber plain weave fabrics was used as the reinforcement material. Quasi-static punch shear test (QS-PST) was applied to the samples to understand the penetration behavior of the samples. The damaged areas were investigated and related to force-displacement curves. The results showed that the neat form of MA-g-PP exhibited 158% more energy absorption than the neat form of MA-g-ABS. In the samples containing one layer of fabric, the highest improvement was observed in the aramid fabric-reinforced MA-g-ABS matrix composites. Aramid fabric increased the energy absorption at a rate of 142.3% in comparison to the neat MA-g-ABS, while carbon fiber fabric and glass fiber fabric increased it by 40% and 63.52%, respectively. Aramid fiber fabric provided no significant improvement in the energy absorption in the MA-g-PP matrix composites, while carbon and glass fiber fabrics contributed to energy absorption at a rate of 48% and 41%, respectively.

Microstructure and Mechanical Properties of Spark Plasma Sintered Nanocrystalline TiAl-xB Composites (0.0 &lt;x&lt;1.5 at.%) Containing Carbon Nanotubes

This paper investigates the effects of minor additions of carbon nanotubes (CNTs) and boron on the structure and mechanical properties of nanocrystalline TiAl intermetallic compound. Nanocrystalline TiAl-xB(0.0 < x < 1.5 at.%) composites containing 1 wt.% CNT were synthesized by mechanical alloying and spark plasma sintering. Microstructure and mechanical properties of samples were evaluated using a scanning electron microscopy, energy-dispersive x-ray spectroscopy, elemental mapping, differential scanning calorimetry, Vickers hardness measurement, and shear–punch test. The findings of the current study show that milling up to 40 h results in the formation of Ti(Al) solid solution. Further milling up to 60 h is associated with a complete amorphization of the structure. Results also show that spark plasma sintering leads to the transformation of Ti(Al) solid solution into a mixture of Ti3Al, Ti2Al, and TiAl intermetallic compounds. Minor additions of boron and CNTs cause a significant grain refinement. The addition of the latter significantly improves the elongation as well. The implications of boron/CNT additions for the microstructure of TiAl and how it correlates with the mechanical properties are thoroughly discussed in this paper.

Dielectric spectroscopy and structural characterization of nano-filler-loaded epoxy resin

This work outlines the characterization of epoxy resin [Bisphenol A-(epichlorhydrin): epoxy] and hardener [[Formula: see text](3-dimethylaminopropyl)-1,3-propylenediamine] with various inorganic nano-fillers. Dielectric characterizations of epoxy, hardener, neat epoxy (epoxy + hardener) and nano-epoxy (nano-filler + neat epoxy) composites loaded with 1 wt.% of inorganic nano-fillers (SiO2, Al2O3, TiO2 and ZnO) were carried out using precision LCR meter, over the frequency range of 1 kHz–2 MHz at a constant temperature of 300.15 K. The structural information of nano-fillers, neat epoxy and nano-epoxy composites was understood by Fourier transform infrared spectroscopy and by XRD. Moreover, hardness and shear strength (shear punch) were also determined in order to gain additional information about the mechanical properties of epoxy composite. Influence of inorganic nano-fillers on the dielectric properties, structural chemistry and mechanical properties of neat epoxy composite is discussed thoroughly in this study.

Assessment of Durability Properties of Reclaimed Asphalt Pavement Using Two Rejuvenators: Waste Engine Oil and Asphalt Cement (60-70) Penetration Grade

The production of asphalt pavements using Reclaim Asphalt Pavement (RAP) has achieved economic and environmental benefits. However, one of the main challenges when using untreated RAP in pavement construction is the hardness of the binder due to aging. The purpose of this study is to recycle and restore damaged asphalt using two types of regenerative agents: Waste Engine Oil (WEO) and Asphalt Cement (AC (60-70)) Penetration Grade. Five ratios (1, 1.5, 2, 2.5 and 3) % of both types of regenerators were added to the RAP, separately, for the purpose of regeneration. Marshall Test was performed on the regenerated samples in order to obtain the optimum ratios for the regenerative additives, which will be adopted in subsequent tests, which include; indirect tensile strength (ITS), tensile strength Ratio (TSR) and Duple Punch Shear Strength Test (DPSST) to evaluate the performance of regenerated RAP mixes and compare them with the original RAP. The results indicated that (1.5 and 3) % are the optimal ratios for (WEO and AC (60-70)), respectively. In addition, the results of the performance tests indicated that the regenerated RAP mixes are better than the original RAP in terms of cracking resistance, stripping resistance and resistance to moisture damage, as well as achieving the specification requirements for the surface course. It can be concluded that rap recycling using (WEO and AC (60-70)) is an effective process that reduces paving costs, reduces environmental pollution and leads to gain sustainable paving.The first section in your paper

Microstructure and superplasticity of Mg–2Gd–xZn alloys processed by equal channel angular pressing

Abstract Microstructure, mechanical properties and superplastic behavior of Mg–2Gd–xZn (x = 0, 1, 2 and 3 wt%) alloys were investigated after extrusion and equal channel angular pressing (ECAP). After only 2 passes of ECAP, a homogenous fine-grained microstructure with a grain size of 2.33 μm and a high fraction of high-angle grain boundaries of 84% were formed in the Mg–2Gd–3Zn (GZ23) alloy, while 4 ECAP passes were necessary to create such a structure in the other alloys. This was attributed to the higher solute drag effect in the other alloys, retarding dynamic recrystallization (DRX). Although DRX occurred more easily in the GZ23 alloy, the final DRX grain size was slightly coarser compared to the other alloys. Shear punch testing (SPT) showed that grain refinement during ECAP leads to a slight increase in the shear yield strength of all studied materials after 2 ECAP passes, which was mostly balanced by texture softening caused by the shear texture component and grain growth after 4 ECAP passes. Contrary to the other alloys, the GZ23 alloy exhibited superplastic behavior after a lower number of ECAP passes. In addition, the superplastic temperature for GZ23 was 648 K, which was lower than the 673 K observed for the other alloys. The m-values of ~0.45–0.5 and activation energies of 98–114 kJ/mol suggested grain boundary sliding (GBS) controlled by grain boundary diffusion as the dominant deformation mechanism in the superplastic regime. This was confirmed by microstructural observations.

Effects of pre-heat treatment of the consumable rod on the microstructural and mechanical properties of the friction surfaced Al-Cu-Mg alloy over pure aluminum

In this study, the effects of the traverse speed and the pre-heat treatment of the AA2024 consumable rod on the mechanical and microstructural properties of the friction surfaced coating over AA1050 aluminum are investigated. The mechanical and microstructural properties of the coatings are characterized using optical and scanning electron microscopy, macrotexture measurement using X-ray diffraction, and the shear punch test. The results show that in both coatings fabricated by solid solutionized and T3-treated consumable rods, by increasing the traverse speed, the deposition rate decreases, leading to a reduction in the volume of the deposited material. Moreover, the T3 heat treatment of the consumable rod results in a smaller grain size in the coating. Regardless of the consumable rod's pre-heat treatment conditions, the size of the Al2CuMg precipitates in the coating increases by increasing the traverse speed. Friction surfacing using a solid solutionized consumable rod increased and decreased the shear and recrystallization texture in the coating, respectively. The smaller grains, fine precipitates, and a stronger recrystallization texture in the coatings fabricated by T3-treated consumable rod led to higher levels of strength and hardness in these coatings.