Effects of Lap Configuration on Mechanical Properties and Composition Distribution of Three-layer Overlapped Laser Weldments on Al/Cu Dissimilar Materials

Battery cells are connected via bus-bars to meet performance requirements, such as power and capacity, and multiple layers of dissimilar materials functioning as anodes, cathodes, or bus-bars are overlapped and welded together. In laser welding, the formation of brittle intermetallic phases in the weld joint is inevitable and, in turn, deteriorates the mechanical properties. To obtain the desirable joint performance, appropriate welding parameters to avoid intermetallic phase formations and joint designs to release stress concentrations must be obtained. This study investigates the effects of lap configurations and process parameters on the tensile-shear load, T-peel load, and composition distribution when multi-layered joints of dissimilar materials are produced by laser welding. Two layers of 0.4 mm Al sheets were welded with a single 0.2 mm Cu sheet, which was emulated using electric vehicle battery interconnects. The results show that the penetration depth varied in accordance with the lap configuration even under the same heat input condition. The lap configuration and welding parameters influenced the composition distribution of the welds, as they altered the solidification rate, number of Cu/Al contact interfaces, and location of the high-density material. The failure load of the T-peel specimens was always lower than that of the tensile-shear specimens except for the Cu−Al−Al lap configuration. The T-peel load of the Cu−Al−Al lap configuration was similar to that of the tensile-shear load. When the stress-concentrated joint was homogeneous, it was more robust.

Study on the test load for the structural test of the flight-load condition of the external fuel tank for fixed-wing aircraft

In this study, for the purpose of conducting the structural tests for the verification of structural soundness of the flight-load conditions of the external fuel tank for the fixed-wing aircraft, the flight load acting on the external fuel tank was converted to test load and the suitability of the converted loads was verified. The loads imposed on the external fuel tank were expressed as the combination of the inertial load (based on the acceleration in the translational direction) and the tangential direction inertial load (based on the angular acceleration of the moment). To calculate the test load, the transfer function table was generated by calculating the shear load and moment based on the unit load. For this purpose, a transfer function table was established by dividing the external fuel tank into a few sections and calculating the shear load and moment generated by the unit shear load and unit moment in each section. In addition, the test load for each section was calculated by computing the established transfer function table and flight-load conditions. However, in actual structural tests, it is often not possible to impose a load in the same position as the point at which the shear load and moment are calculated. For this reason, the actual test-load positions had to be determined and the calculated test loads were redistributed to those positions. Then, the final test load plan was established by applying a whiffle tree to increase the efficiency of the test while also making it easier to apply the actuators. Finally, the suitability of the established test load plan was confirmed by comparison with the flight-load conditions.

Applicability of the 500°C isotherm method in determining the strength of reinforced concrete beams after fire

A procedure to estimate the residual bending moment and the shear load capacity after fire in reinforced concrete beams was evaluated. The calculation method is based on the 500ºC Isotherm Method, adopting the reduction coefficients proposed by Van Coile et al. (2014) for the steel yield strength. The proposed method validation was done from experimental results of 62 reinforced concrete beams available in the literature. It was possible to observe a good approximation of the analytical method with the experimental data. For the bending moment an average ratio M r ana / M r exp of 1.04 and standard deviation of 0.15 was found. For the shear force an average ratio V r ana / V r exp of 0.85 and standard deviation of 0.23 was found.

Experimental Evaluation of Tension and Shear Responses of Material Discontinuities in Origami-Based Sheet Metal Bending

Origami-based sheet metal (OSM) bending uses the origami concept to form a three-dimensional (3D) structures from a two-dimensional (2D) sheet by a series of bending operation. The OSM bending relies on a material discontinuity (MD) to perform the bending operation where the MDs are subjected to tension and shear load. Even though the OSM bending is a process that is simple, cost-effective, and easy to integrate into mass production, the understanding of the OSM bending mechanics is limiting its wide application. Particularly, the deformation behavior of MDs under tension and shear load remains unknown. Hence, this work investigates the response of MDs to these loads using the standard tension and shear tests. From the tests, critical values for two different ductile fracture criteria (DFC) are determined, and the possibility of a failure occurring in OSM bending is predicted. Results show that the load-bearing capability of the MDs is related to change in the effective cross-section area of a MD. Simple tension and shear tests can provide a simple procedure to predict failure in OSM bending. The impact of self-contact occurred under shear load influences maximum shear force and accuracy of failure prediction.

Theoretical Analysis for Stability Evaluation of Rock Mass Engineering Structure under Combined Compression-Shear Loading: A Case Study of Inclined Pillar

An inclined pillar is a typical support structure under compression and shear loads for underground mining. The shear load caused by the inclination of the ore-body affects the bearing capacity of the pillar. At present, there is no systematic investigation on the influence of shear load on the stress state evolution and bearing capacity of the inclined pillar. Additionally, there is still a lack of effective evaluation of the bearing capacity of the inclined pillar in the presence of additional shear load. In this research, the theoretical analysis method is used to solve these problems. First, the compressive and shear load components on the inclined pillar were calculated by the tributary area method, and the average stress state of the inclined pillar, considering the influence of the shear load, was characterized by a series of generalized stress circles. The factors that affect the shear load, such as the area extraction ratio, the inclination of the ore-body, and the in-situ stress ratio, were analyzed, and it reveals that there are three kinds of stress paths of the inclined pillar and their trajectories are straight line, circle, and curve, respectively. Then, a shear strength model was proposed to evaluate the bearing capacity of inclined pillars. The expression of this model is multiplied by a vertical pillar strength model and a dimensionless coefficient that is named the contribution factor of shear load (CFSL). Some cases of inclined pillars were employed to verify the rationality of this model. Finally, the factors that affect the bearing capacity of pillars were analyzed. This investigation presents that the shear load affects the stress path and determines the bearing capacity of the pillar. Therefore, the shear load should not be neglected in pillar design and stability analysis.

Musculoskeletal biomechanics of patients with or without adjacent segment degeneration after spinal fusion

Study design A retrospective, single center, case-control study was performed. Objective The present study employed patient-specific biomechanical modeling to find potential biomechanical differences after spinal fusion at L4/5 in patients with and without subsequent development of adjacent segment disease (ASD). Methods The study population comprised patients who underwent primary spinal fusion at L4/5 and were either asymptomatic during > 4 years of follow-up (CTRL; n = 18) or underwent revision surgery for ASD at L3/4 (n = 20). Landmarks were annotated on preoperative and follow-up lateral radiographs, and specific musculoskeletal models were created using a custom-built modeling pipeline. Simulated spinal muscle activation and lumbar intervertebral shear loads in unfused segments were analyzed in upright standing and forward flexion. Differences between the pre- and postoperative conditions were computed for each patient. Results The average postoperative muscle activity in the upright standing posture was 88.4% of the preoperative activity in the CTRL group (p < 0.0001), but did not significantly change from pre- to postoperatively in the ASD group (98.0%). The average shear load magnitude at the epifusional joint L3/4 during upright standing increased from pre- to postoperatively in the ASD group (+ 3.9 N, +/− 17.4 (n = 18)), but decreased in the CTRL group (− 4.6 N, +/− 23.3 (n = 20); p < 0.001). Conclusion Patient-specific biomechanical simulation revealed that spinal fusion surgery resulted in greater shear load magnitude and muscle activation and therefore greater forces at the epifusional segment in those with ASD compared with those without ASD. This is a first report of patient-specific disc load and muscle force calculation with predictive merits for ASD.

Appraisal of Anchor Arrangement and Size On Sand-Geogrid Interaction In Direct Shear

Soil – reinforcement interaction is a major factor in the analysis and design of reinforced earth structures. In current research the effects of attaching elements of different size and numbers as anchors on enhancement of interaction at soil - geogrid interface under direct shear conditions were studied. Poorly and well graded sands (SC & Sf), a high density polyethylene geogrid, anchors with three different size and numbers (layouts) and clamping length of 2cm from shear surface were used. Samples were prepared dry at a relative density of 80% in a 30×30cm direct shear box and subjected to normal pressures of 12.5, 25 and 50kPa with the shear load applied at a rate of 1mm/min. Results of the assessment show that anchored geogrids improve shear resistance at interface mainly due to mobilization of passive soil resistance that is significantly influenced by the magnitude of the normal pressure and the number and size of anchors. Interaction enhancements achieved varied between a minimum of 8% and a maximum of 42%.

ACTIVITY TO PREVENT EMERGENCY SITUATIONS OF CASCADE TYPE OF SPREADING RELATED TO SOIL LANDSLIDE

Landfills for solid waste with liquidation energy-intensive technological equipment, due to emergencies of the cascade type of distribution associated with the landslide of landfills, pose a man-made environmental hazard. Experimental studies to determine the effect of humidity, density, temperature of landfill soils on the stability of slopes on landslides have shown that with increasing humidity and temperature, the resistance of the array to displacement decreases. The lower the density, the greater the ability to penetrate and saturate with moisture, which creates additional shear load. According to the results of experimental research, a method of prevention of cascade-type emergencies related to landfill landslides at the landfill with liquid energy-intensive technological equipment has been developed to prevent the consequences of danger from escalating from site to higher levels of distribution. The method consists of measures "before" and "after" the fact of moving the landslide.