Tensile Shear Load Research Articles

Dynamic deformation and fracture of brass: Experiments and dislocation-based model

In this work, we perform a comprehensive study of the dynamic deformation and fracture of brass, including Taylor tests with classical and profiled cylinders and ball throwing experiments reaching the strain rates of about (0.1−1)/μs, as well as atomistic and continuum-level numerical modeling. Molecular dynamics (MD) simulations are used to construct the equation of state (EOS) of brass and to study its fracture characteristics at shear deformation under negative pressure. An original model of fracture under combined tensile-shear loading is formulated, which takes into account both the accumulation of empty volume in the process of lattice loosening due to the lattice defect production in the course of plastic deformation and further mechanical growth of voids controlled by the dislocation plasticity. This atomic-scale model is transmitted to the macroscopic experiment-scale level and embedded into 3D dislocation plasticity model to describe the dynamic deformation and fracture of brass using the numerical scheme of smoothed particle hydrodynamics (SPH). A part of experimental data is used to find the optimal parameters of the dislocation plasticity model by means of the Bayesian global optimization method accelerated with the help of artificial-neural-network (ANN)-based emulator of the 3D model. Another part of experimental data is used to fit the fracture model parameter. The remaining experimental data, which are not used in the parameterization, are applied to verify the parameterized model. The developed physical-based model provides correct and meaningful description of the dynamic deformation and fracture of brass, while the developed formalized approach to its parameterization opens a way to wider use of this type of models in the engineering applications, including studies on dynamic performance and high-speed processing technologies.

A novel dissimilar resistance spot welding of Ti6Al4V alloy and 316L stainless steel via copper as interlayer by using optimal electrodes

A novel dissimilar resistance spot welding of Ti6Al4V alloy and 316L stainless steel was performed via copper as interlayer by using optimal electrodes. A significant improvement in nugget morphology being of less defects was achieved with increasing the copper interlayer thickness from 50 μm to 400 μm. Thinner interfacial reaction layers at both the nugget/titanium interface and the nugget/stainless steel interface and finer equiaxed dendritic grained structure at the inner nugget were formed with copper interlayer thickness of 300 μm compared with those without interlayer. The formation of TiCu and Ti2Cu was facilitated with the incorporation of Cu into the nugget, which effectively inhibited the formation of the brittle Ti–Fe intermetallic compounds including Fe2Ti. The nugget in the welded joint with copper interlayer in 300 μm thickness exhibited a far lower microhardness than that of the interlayer-free welded joint, and the average microhardness reduced to 604 HV in the inner nugget, which was about 36% lower than that of the interlayer-free welded joint. The tensile shear load of the welded joint exhibited an increased tendency with increasing interlayer thicknesses from 50 μm to 300 μm, and the maximum tensile shear load of 6.3 kN was obtained with the interlayer thickness of 300 μm, which was ∼97% higher than that of the interlayer-free welded joint. The welded joint with copper interlayer exhibited hybrid ductile and fragile fractured characteristics. The work would provide a facile and cost-effective method to achieve a reliable welded joint of Ti alloy and stainless steel.

Microstructure and performance of joint of Al/Cu welded by resistance element welding with an auxiliary gasket

A 1060 commercial-purity aluminum and T2 pure copper plates with a thickness of 2 mm were welded by using resistance element welding with an aluminum rivet and auxiliary gasket. The interfacial microstructure was analyzed, and the tensile shear load of the joint was tested. In the joint welded, a layer of Al2Cu adjacent to the copper and the eutectic structure of Al2Cu + (Al) near the nugget region were formed at the interface of Al/Cu. The tensile shear load of the joint increased first and then decreased with the increase of welding current, and it reached the maximum of 2.24 kN when the welding current was 26 kA. The results reveal that the application of the auxiliary gasket not only promote the thickening of the nugget, but also achieve the joining between the rivet leg and the upper plate when resistance element welding of Al/Cu is performed.

Quantitative Study of Predicting the Effect of the Initial Gap on Mechanical Behavior in Resistance Spot Welding Based on L-BFGS-B.

The initial gap (IG) is frequently occurring in the process of resistance spot welding (RSW) for automotive body-in-white structures. It is an inevitable challenge that the RSW with IG can negatively impact the welding quality, subsequently reducing the structural integrity and safety of the vehicle. This research aims to study the influence of the IG on RSW mechanical behaviors based on the refined finite element model (FEM) of RSW with different IGs under tensile shear load. The influence of six types of IGs on the peak load and fracture modes of RSW of plates with similar thicknesses of 1.0 mm and 1.5 mm is investigated through FEM and experiments. To quantify the influence of the IG on the RSW's deformational behavior, a prediction model is introduced to predict the peak load of RSW with different IGs. The prediction model is locally optimized through the Limited memory Broyden Fletcher Goldfarb Shanno (L-BFGS-B) optimization algorithm. Based on the prediction model, the relationship among the peak load values of the tensile shear specimens, the IG, and the mechanical behavior of the RSW is revealed. The results show that the IG has an obvious influence on the peak load values of RSW under tensile shear load, and the fracture modes are both the pull-out fracture (PF) mode. The peak load values of the RSW's tensile shear specimens are decreased with the increment in the IG. Finally, the prediction model can accurately predict the peak load for various IGs, with errors of no more than 3%.

Microstructure and properties of Mg/Ti joint welded by resistance spot welding with an aluminum interlayer

Magnesium alloy AZ31B and titanium TA2 were welded by resistance spot welding technology employing an interlayer of aluminum foil and asymmetric electrodes. The microstructure of the joint was observed, with an analysis conducted on the impact of welding current and welding time on the tensile shear load of the joint. During the welding process, the aluminum interlayer melted and blended with the molten magnesium alloy, leading to the formation of a eutectic layer consisting of Mg17Al12 and (Mg) in close proximity to the welding interface. As the increasing of welding current or the extending of welding time, there was an initial increase followed by a slight decrease in the tensile shear load of the AZ31B/TA2 joint. At a welding current of 16 kA, the tensile shear load of the joint achieved the maximum, which was approximately 6.48 kN. The findings suggest that it is effective to use an aluminum foil as an intermediary to regulate the metallurgical reaction at the interface and utilize nonsymmetrical electrodes for thermal compensation in the resistance spot welding between titanium and a magnesium alloy.

Experimental behavior and fracture prediction of a novel high-strength and high-toughness steel subjected to tension and shear loading tests

In this study, laboratory testing and numerical simulation methods are used to investigate the mechanical behavior and perform fracture prediction of a novel high-strength and high-toughness steel with a negative Poisson's ratio (NPR) effect under combined tensile-shear loading conditions. A test device capable of meeting different tensile-shear combination test angles is designed and manufactured, wherein the mechanical experiments on the NPR (Negative Poisson's Ratio) steel specimens are carried out at various testing angles. Q235 steel and MG400 steel are used as experimental control groups. The results show that the mechanical deformation of NPR steel is significantly better than that of Q235 steel and MG400 steel. Its tensile-shear test curve has no yield plateau and it has quasi-ideal elastic-plastic mechanical properties. The loading direction gradually changes from tension-dominated to shear-dominated as the tension-shear angle increases, and the strength and deformation of the specimens show a decreasing trend. Based on the laboratory test results, a finite element numerical model of NPR steel is established. A series of numerical simulations are carried out under the conditions of different tension and shear angles and the average stress triaxiality and fracture strain data are obtained. The fracture data of NPR steel are fitted using the Johnson-Cook fracture criterion, and the Johnson-Cook fracture parameters under the tensile-shear test conditions of NPR steel are thus obtained. The numerical simulation verifies that the fracture model can accurately predict the tensile-shear fracture behavior of NPR steel.

Interfacial microstructure and mechanical property of dissimilar resistance spot welded joint of TC4 titanium alloy and 316L stainless steel with nickel interlayer

Dissimilar materials of TC4 titanium alloy and 316L stainless steel were joined by means of resistance spot welding with nickel interlayer in different thicknesses. A significant enhancement in terms of nugget morphology quality with less defects was achieved for the welded joints with nickel interlayer compared with that without interlayer. With increasing the nickel interlayer thickness from 50 μm to 300 μm, the effective nugget diameter increased gradually from ∼4.8 mm to ∼5.2 mm, which was lower than that of the interlayer-free welded joint being ∼5.9 mm. A thinner intermetallic compound layer with dual-layered structure features with thickness of ∼11 μm was formed at the nugget/titanium interface in the welded joint with nickel interlayer compared with that of the interlayer-free welded joint, meanwhile an intermetallic compound layer with thickness of ∼3 μm was formed at the nugget/stainless steel interface, which exhibited serrated structure features. The introduction of nickel interlayer in the welded joint could suppress the formation of the brittle Ti–Fe intermetallics such as Fe2Ti, and facilitate the formation of TiNi, Ti2Ni and TiNi3. A more homogeneous current density distribution and a lower peak temperature (1809 °C) during welding were achieved via employing nickel interlayer. With increasing nickel interlayer thickness from 0 μm to 300 μm, the tensile shear load of welded joints experienced an increased tendency first and then decreased, meanwhile the maximum tensile shear load of 3.7 kN was obtained with the interlayer thickness of 200 μm, which was 61% higher than that of the interlayer-free welded joint.

Experimental and numerical research for the failure behavior of the dieless clinching joints

In this work, the failure behavior of dieless clinching joints for AA5052-H32 aluminum alloy under cross tension and tensile shear loading conditions was investigated by experimental and simulation methods. Firstly, The VUMAT subroutine for the N–H shear-modified GTN model (Proposed by Nahshon and Hutchinson, a modified GTN model considering hole shear effects) was written. Subsequently, the conventional and shear parameters calibration was accomplished. A finite element model (FEM) for the failure process of dieless clinching joints based on the N–H shear-modified GTN microscopic damage model, elimination of large deformation mesh distortion and consideration of the material hardening history was established. In addition, the deformation, damage and destruction processes of the joint under two loading conditions were analyzed. And macro/microfracture analysis of the failed joints was performed to further reveal the failure behavior. The results show that the established FEM of the failure process agrees well with the experimental results and failure modes are consistent. The model accuracy in predicting the tensile and shear loads is 91.9% and 92.7%, respectively. This provides a reference for the process design and joint arrangement of the dieless clinching joints in practical applications.

In‐situ polymerizable thermoplastic and bio‐epoxy based composites for offshore renewable energy applications

AbstractThis study evaluates various quasi‐static mechanical properties of an in‐situ polymerizable thermoplastic and a bio‐based thermosetting composite comprising of non‐crimp fabric reinforcement for potential use in the next generation of Offshore Wind and Tidal Power platforms. Mechanical properties are characterized under tensile, flexural, in‐plane shear and interlaminar shear loading. Results reveal that the evaluated properties differ based upon matrix type. Fractographic evidence from scanning electron microscopy is used to explain the differences observed and was generally consistent in terms of revealing cohesive failure at the fiber‐matrix interface for the thermoplastic composite and contrasting adhesive failure for the thermosetting composite. For glass fiber reinforcement, the thermoplastic composite is superior in terms of flexural 90° properties (+20%) while the thermosetting composite performed better in flexure 0° in terms of both strength (+15%) and modulus (+25%). In terms of interlaminar shear, the thermosetting composite exhibited higher strength (+14%) while Tensile and in‐plane shear properties are similar for composites of both resin systems. Overall, neither composite is superior in terms of overall mechanical properties and both matrices show promise as a stepping stone towards the use of more sustainable constituents in offshore structures.Highlights Quasi‐static mechanical performance and failure analysis of relatively sustainable composites are presented. Failure analysis indicate cohesive failure of the thermoplastic based composite and interfacial failure of the thermosetting based composite. Proposed composites are benchmarked against the composites manufactured using conventional resins. Overall, both matrices show promise as a stepping stone towards more sustainable offshore structures.

Numerical simulation and experimental investigation of resistance spot welding with initial gap under tensile shear load

In the resistance spot welding (RSW) process of body structures, the initial gap (IG) occurs frequently. The RSW with IG impact welding quality, and subsequently reducing the structural safety of the whole vehicle. An equivalent displacement method (EDM) is proposed, and a refined finite element model (FEM) is established to accurately simulate the mechanical responses of the RSW with IG under tensile shear loading. This research chose 3 IGs (0 mm, 3 mm and 5 mm) of RSW for investigation. First, a true stress-strain curve of base metal (BM) is obtained by uniaxial tensile test, and hardness of the 3 zone is obtained through hardness test. Then, the stress-strain curves of heat-affected zone (HAZ) and fusion zone (FZ) are fitted from those of BM based on relationship between Vickers hardness and tensile strength. Then, the refined 3D FEM of RSW with initial gaps are established based on EDM. Finally, the model is nonlinear analyzed and compared with the experiment. The results show that the force and displacement curves obtained through simulation are highly consistent with the ones obtained through experiments with the maximum mean integrated relative error (MIRE) is 7.42 %. The average error of the maximum load-bearing capacity is 1.05 %, and the maximum error is 2.58 %. The failure modes are both button pullout, attributed to the relatively low strength of BM. And cracks occur in BM near HAZ and penetrate along the sheet thickness direction. These findings show that numerical simulation of RSW with IG, based on the EDM, effectively reflects its mechanical properties and failure behaviors.

Strength Optimisation of Hybrid Bolted/Bonded Composite Joints Based on Finite Element Analysis.

A finite element analysis (FEA) was conducted to examine the behaviour of single-lap quasi-isotropic (QI) and cross-ply (CP) hybrid bolted/bonded (HBB) configurations subjected to tensile shear loading. Several critical design factors influencing the composite joint strength, failure conditions, and load-sharing mechanisms that would optimise the joining performance were assessed. The study of the stress concentration around the holes and along the adhesive layer highlights the fact that the HBB joints benefit from significantly lower stresses compared to only bolted joints, especially for CP configurations. The simulation results confirmed the redundancy of the middle bolt in a three-bolt HBB joint. The stiffness and plastic behaviour of the adhesive were found to be important factors that define the transition of the behaviour of the joint from a bolted type, where load sharing is predominant, to a bonded joint. The load-sharing potential, known as an indicator of the joint's performance, is improved by reducing the overlap length, using a low-stiffness, high-plasticity adhesive, and using thicker laminates in the QI layup configuration. Enhancing both the ratio of the edge distance to the hole diameter and washer size proves advantageous in reducing stresses within the adhesive layer, thereby improving the joint strength.

Discussion on ultimate resistance formulas of high-strength bolts under tensile-shear coupling loading

Bolted connections are one of the key connection configurations in steel structures. The ductile fracture prediction is one of the challenges in the structural integrity evaluating of steel structures. To guarantee the safety of steel bridge in connections, an accurate assessment of the ultimate resistance of high-strength bolts under combined tensile-shear loads is necessary. However, the impacts of various parameters on high-strength bolts under combined tensile-shear loads are not sufficiently analysed in the existing references. Hence, in this paper, the validated mesoscale critical equivalent plastic strain (MCEPS) method is used to evaluate the ultimate resistance of high-strength bolts with different bolt grades, bolt diameters, bolt types, hole clearance, and preload force when the bolts are exposed to combined tensile-shear loading. The simulation results are compared to existing design specifications. Finally, the formula modifications in the existing design standards are proposed based on statistical analysis on numerical parametric results.

Significant improvement in tensile shear properties of friction stir lap welded nano TiB2/2024 Al composite joints via a novel tool pin geometry design

A novel designed tool pin with two shoulders and pins (stepped pin, S-pin) was performed to fabricate the friction stir lap welded nano-TiB2/2024 Al composite joints for the interface migration optimization and tensile shear strength improvement purposes. Compared with the conventional tapered pin (T-pin) joints, broken and dispersedly distributed hook, significantly restrained cold lap were observed in the S-pin joints. Submicron or hundreds of nanometers grains were detected in the stir zone (SZ), which should be attributed to the existence of nano-TiB2 hindering the movement of grain boundaries and limiting the growth of recrystallized grains. A wedge-shaped microhardness distributions of the S-pin joints were found, which would be better for the joint bearing capacity. Tensile shear loads of the S-pin joints were much higher than those of the T-pin joints. The optimal average tensile shear strength, 7.3 kN or 484 N/mm, were obtained when the S-pin was performed, dominantly fracturing in the heat affected zone (HAZ) rather than the SZ.

Effects of the processing parameters and laser textures in friction stir spot welding of Al alloy and polyimide joints

In this paper, friction stir spot welding (FSSW) technology was introduced to join 7075 Al alloy to polyimide (PI) sheets. The effects of the FSSW parameters and laser textures on the microstructure and tensile shear load of the Al/PI joint were studied. The optimum FSSW parameters were the rotation speed of 2400 r/min, the plunge depth of 0.4 mm, the dwell time of 20 s, and the plunge speed of 10 mm/min. The tensile shear load of the joint increased owing to the laser textures in the Al alloy surface. Cross-sections showed that the mechanical locking was found between the Al alloy and PI. The XPS results revealed that no chemical bond were formed at the welding interface after laser textures. The joining mechanism of Al 7075 and PI was main the mechanical locking.

Understanding the mechanisms behind ultrasonic vibration in resistance spot welding of aluminum and steel

An ultrasonic-assisted resistance spot welding process, which can improve the quality of aluminum/steel spot-welded joints, has been developed. However, the mechanism of the thermal-electrical-mechanical behavior caused by the ultrasonic longitudinal vibration to welding process has not been clarified. In this study, the role and impact mechanisms of ultrasonic longitudinal vibration during the welding process to form joints were confirmed by combining the microstructural characterization of the formed joints with the signal analysis of the process, as well as the analysis of the independent finite element numerical calculation results. Additionally, the interface metallurgical reaction behavior, welding defects, fracture behavior, and joint strength characteristics of ultrasonic-assisted aluminum/steel resistance spot welding joints were comprehensively analyzed, and the results indicated that the sizes of the aluminum/steel nuggets decreased. It could be attributed to the competition among multiple ultrasonic effects. Specifically, ultrasonic vibration decreased the contact resistance between the aluminum/steel sheets, whereas the acoustic cavitation and acoustic streaming effects increased the electrical conductivity of molten steel and thermal conductivity of molten aluminum, respectively. Moreover, ultrasonic vibration promoted the radial creep of molten and near-molten aluminum, which expanded in the effective bonding area between the two workpieces. Furthermore, ultrasonic vibration effectively reduced the thickness of the intermetallic compound layer (<3.0 µm), concurrently inhibited the formation of interfacial welding defects. Finally, the peak tensile-shear load of aluminum/steel joints is significantly increased under multiple ultrasonic optimization mechanisms.

Parameter optimization, microstructural and mechanical properties of fiber laser lap welds of DP1200 steel sheets

In this research, the effects of laser power, laser welding speed and laser incidence angle were evaluated in terms of weld geometry, microstructure, microhardness, fracture surfaces and tensile shear load in fiber laser welding joints of DP1200 steel sheets. Response Surface Methodology (RSM) was utilized to derive mathematical relationships between the process parameters and the tensile shear load after the tensile test. The optimum combination of process parameters was a laser power of 2800 W, a laser welding speed of 40 mm/s, and a laser incidence angle of 70°. A thermal camera was used to record the laser welding process, and the cooling rates were evaluated by analyzing this data. The influence of cooling rate upon microstructure phase formation for DP1200 steel is investigated, with continuous cooling transformation (CCT) diagrams. Also, post-welding stress and displacement were simulated by Simufact Welding software. At high heat input (55.79 J/mm) occurred coarse dendritic martensitic lath growth while at low heat input (37.6 J/mm) fine dendritic martensitic structure was observed in the weld zone was obtained owing to the high rate of cooling. The microstructure consists of full martensite at a higher than 10 °C/s cooling rate. The findings reveal that the phases in FZ and HAZ, the morphology and martensite/bainite constituents differed related to the heat input and laser incidence angle, which ultimately affects the joint’s microhardness, fracture dynamics and tensile shear load.

Enhanced formation quality and tensile shear load of 7B04 aluminum alloys lap joint by impacting flow friction stir lap welding

Avoiding the upward-bending hook is a highly pressing and challenging task in the field of similar aluminum alloys friction stir lap welding (FSLW). To enhance formation quality and then obtain the welded lap joint with high tensile shear load, a novel impacting flow FSLW (IF-FSLW) process based on the X-shape reverse-threaded pin was proposed in this study. Three welding tools with different tool geometry parameters were developed to analyze how the locations of the materials accumulated zone (MAZ) influenced the joint formation and the joint loading capacity, and 7B04 aluminum alloys were chosen as research subject. Results showed that the horizontally-impacting and vertically-impacting effects of MAZ on and above the original lap interface made the hook respectively present the forky structure at the end and the downward-bending morphology, and the horizontally-impacting effect of MAZ made the stir zone (SZ) have a protruding morphology near the MAZ. Under the tensile fracture mode, the IF-FSLW joint under configuration A had a greatly heightened tensile shear load under the combined actions of the downward-bending hook and the enlarged SZ. The tensile shear load of IF-FSLW joint reached 8.62 kN/mm under the reasonable combination of tool geometry parameters and welding process parameters. The IF-FSLW process by the X-shape reverse-threaded pin provides an effective way to obtain a superb-strength lap joint of aluminum alloys.

Extrinsic-Riveting Friction Stir Lap Welding of Al/Steel Dissimilar Materials.

To obtain high-quality joints of Al/steel dissimilar materials, a new extrinsic-riveting friction stir lap welding (ERFSLW) method was proposed combining the synthesis advantages of mechanical riveting and metallurgical bonding. SiC-reinforced Al matrix composite bars were placed in the prefabricated holes in Al sheets and steel sheets, arranged in a zigzag array. The bars were stirred and mixed with Al sheets under severe plastic deformation (SPD), forming composite rivets to strengthen the mechanical joining. SiC particles were uniformly dispersed in the lower part of the welding nugget zone (WNZ). The smooth transition between the SiC mixed zone and extrinsic-riveting zone (ERZ) ensured the metallurgical bonding. The maximum tensile shear load of the joints reached 7.8 kN and the maximum load of the weld per unit length was 497 N/mm. The fracture occurred at the interface between the rivets and steel sheets rather than the conventional Al/steel joining interface. Moreover, ERFSLW can prolong the service life of joints due to three fracture stages. This method can be further extended to the welding of other dissimilar materials that conform to the model of "soft/hard".

The Pre-Heating Effect for Porosity Control during the Laser Welding of Galvanized Steel Sheets

Recently, for the high performance of automobiles, the application ratio of zinc-coated steel sheets with excellent corrosion resistance has been increasing. However, it is difficult to achieve sound welds, as porosities form from zinc during welding. In this study, a laser welding process, with the addition of a pretreatment step to conventional laser welding, was devised to improve weld quality by eliminating pores caused by zinc in the welds. Laser welding was performed on the overlapping joint of hot-dip galvanized steel sheets (SGARC 340, Hyundai Steel., Suncheon-Si, Jeollanam-do, Republic of Korea), with a thickness of 1.2 mm in the upper sheet and 0.9 mm in the lower sheet, and the welding characteristics were investigated by varying the laser power and focal position. Compared to conventional laser welding, the three-step laser stitch welding process significantly reduced the degree of spatter generation and welding defects. Additionally, it increased the tensile–shear load by approximately 37%. Moreover, the reduction in the zinc component of the three-step laser stitch welds was confirmed through SEM-EDS analysis. These findings contribute valuable information for securing high-quality welding joints and effectively addressing zinc-coated steel sheet welding quality issues in the automotive and industrial sectors.

STUDYING THE STRENGTH OF DISSIMILAR JOINTS OF AISI 430 AND 301 STAINLESS STEEL WELDED AT DIFFERENT WELDING PARAMETERS

Investigating the best welding parameters for resistance spot welding joints between AISI 430 and AISI 301 stainless steels was the primary focus of this study. This research involved welding samples of these stainless steel types using various welding parameters. Ferritic stainless steel (AISI 430) and austenitic stainless steel (AISI 301) were subjected to resistance spot welding, and different welding conditions were applied to produce a range of samples. The study specifically analyzed the influence of the welding current (2.5, 3.1 and 3.7) kA and welding time (40, 70 and 100) ms on the joining capability of these stainless steels. To determine the best welding parameters, microhardness measurements and tensile-shear tests were performed on the welded materials. The results indicated that increasing the welding current and welding time led to an increase in the tensile load. The maximum tensile-shear load 2036 N was observed at 3.7 kA and 100 ms. However, after a salt spray test (48 and 96) h, a serious decrease in the tensile load from 2036 N to 750 was observed at the high current 3.7 kA and time (70 and 100) ms. At 3.1 kA and 70 ms before and after the salt test, its value remained relatively constant, and the corrosion resistance of the weld joint was at the best level. The microhardness of the heat-affected zone increased, reaching its maximum point (for 3.1 kA and 70 ms: 347.3 HV and for 3.1 kA 100 ms: 369 HV) in the fusion zone. Moreover, the increase in the welding time and current was associated with an increase in the nugget size. The maximum nugget size was 3.61 mm at 3.7 kA and 100 ms.