Mixed-mode tensile/shear fracture of the additively manufactured components under dynamic and static loads

2021 ◽  
pp. 108185
Author(s):  
B. Ameri ◽  
F. Taheri-Behrooz ◽  
M.R.M. Aliha
Keyword(s):  
Mixed Mode ◽  
Shear Fracture ◽  
Tensile Shear ◽  
Static Loads

Loading Direction Versus Crack Propagation Path in a Lead-Free Single Solder Joint Sample

2008 ◽  
Author(s):  
Feng Gao ◽  
Jianping Jing ◽  
Janine Johnson ◽  
Frank Z. Liang ◽  
Richard L. Williams ◽  
...  
Keyword(s):  
Solder Alloy ◽  
Mixed Mode ◽  
Shear Fracture ◽  
Pure Shear ◽  
Shear Loading ◽  
Propagation Path ◽  
Mixed Mode Loading ◽  
Cohesive Failure ◽  
Loading Direction ◽  
Shear Component

In this paper, single solder joints (SSJs) were subjected to moderate speed loading (5mm/sec) in different directions, from pure tensile, mixed mode to pure shear. Fracture surfaces from different loading directions were examined both experimentally and numerically. It is observed that intermetallic compound (IMC) is formed between the solder alloy and the Cu pad, and failure typically occurs at or near the solder/IMC/Cu interfaces on the board side. Pure tensile loading typically leads to interfacial fracture along the IMC/Cu interface. Mixed mode loading usually results in a mixture of interfacial and cohesive failure with crack propagating in a zigzag fashion between the solder/IMC interface and the solder alloy. Loading with higher shear component tends to result in more cohesive failure of the solder alloy near the solder/IMC interface. Under pure shear loading, failure is almost always cohesive within the solder alloy near the solder/IMC interface.

scholarly journals Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 286 ◽  
Author(s):  
Lipeng Deng ◽  
Shuhan Li ◽  
Liming Ke ◽  
Jinhe Liu ◽  
Jidong Kang
Keyword(s):  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Load Capacity ◽  
Maximum Load ◽  
Fusion Welding ◽  
Tensile Shear ◽  
Friction Stir ◽  
Corona Ring ◽  
Spot Welded

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

AN EMPIRICAL RELATIONSHIP FOR ESTIMATING METALLURGICAL AND MECHANICAL BEHAVIOR OF RESISTANCE SPOT WELDED DP800 STEEL JOINTS

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Rajarajan C ◽  
Sivaraj P ◽  
Balasubramanian V
Keyword(s):  
Shear Fracture ◽  
Empirical Relationship ◽  
Testing Machine ◽  
Welding Current ◽  
Fracture Load ◽  
Peak Hardness ◽  
Tensile Shear ◽  
Nugget Zone ◽  
Resistance Spot ◽  
Increase With Increase

Similar joints of DP800 (Dual Phase) steel in lap joint configuration were fabricated using resistance spot welding (RSW) process. The process parameters were optimized using DOE (design of experiments) and the welds joints were fabricated using the obtained DOE matrix. The tensile shear fracture load (TSFL) of joints was evaluated using universal testing machine. Microhardness variations across the weld cross-section was recorded using Vickers’s microhardness tester. Microstructural features were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). From this investigation, it is understood that increase in welding current increases the nugget zone size and it led to increasing the degrease of softening in the HAZ. The tensile shear strength is found to increase with increase in welding current up to a certain limit and then it decreases. The microhardness profile shows a peak hardness in nugget zone and the hardness is lower in the HAZ. The softening of HAZ is mainly attributed to inter-critical heating during welding.

Experimental study of nanoelectroplating steel spot welding structure under impact tensile-shear loading

2021 ◽  
Vol 11 (7) ◽  
pp. 1207-1213
Author(s):  
Chunlei Fan ◽  
Huanran Wang ◽  
Dongfang Ma
Keyword(s):  
Dynamic Loading ◽  
Heat Affected Zone ◽  
Static Loading ◽  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Base Material ◽  
Shear Loading ◽  
Tensile Shear ◽  
Softened Zone

The tensile shear fracture behavior of solder joints under impact load influences the whole vehicle’s safety substantially. This paper takes the QP980 steel resistance spot welding (RSW) structure as the research object to study the tensile-shear fracture behavior of the RSW structure under tensile-shear loading. The microstructure observation of the welded spot shows that the metallographic structure is the martensite. The porosity defects in the melting zone are the primary defect reflecting the obvious plate-cracks on both sides of the nugget. The paper demonstrates the Vickers hardness test result of the spot-welded zone. According to the test, the micro-hardness distribution result shows that the higher the martensite, the greater the hardness. A softened zone emerges adjacent to the heat-affected zone on the welded base material interface. The quasi-static and dynamic tensile-shear tests on the QP980 steel RSW lap-joint specimens show that the fracture on the BM is adjacent to the welded spot under quasi-static loading but close to the heat-affected zone under dynamic loading. Under dynamic loading, the weld seam and softened zone of the welded spot have a direct influence on the fracture. On the recovered specimen’s fractured section, there are a large number of apparent dimples on the section of the BM under quasi-static loading and the section of the HAZ under dynamic loading with nucleation, growth, and aggregation of cavitation, resulting in ductile fracture.

Study of Shear Fracture Behaviours on 6061 Aluminum Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1145-1148
Author(s):  
Hao Zhu ◽  
Yang Zhang ◽  
Shen Wei Yu
Keyword(s):  
Shear Stress ◽  
Aluminum Alloy ◽  
Grain Boundaries ◽  
Shear Fracture ◽  
Tensile Shear ◽  
Shear Tests ◽  
Tensile Direction ◽  
6061 Aluminum Alloy ◽  
Shear Yield

The mechanics properties and fracture behaviors of 6061 aluminum alloy were investigated by the tensile shear tests and in-situ tensile shear tests with tensile shear specimen devised. The results indicate that a lot of slip bands parallel to tensile direction are produced on specimens’ surfaces. With shear strain rates increasing, the shear yield stress and shear ultimate stress of 6061 aluminum alloy remain constant basically, but the shear fracture strain decreased obviously. The grain boundaries of 6061 aluminum alloy are the weakest area and microcracks initiate at the grain boundaries parallel to tensile direction under shear stress. With shear stress increasing, the microcracks extend and coalesce. The fracture of specimens is due to coalescence or shearing between the microcracks.

scholarly journals Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Xin Dong ◽  
Hao Lu ◽  
Houxu Huang ◽  
Yiqing Hao ◽  
Yuanpu Xia
Keyword(s):  
Failure Mode ◽  
Shear Failure ◽  
Lateral Pressure ◽  
Shear Fracture ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Hydraulic Pressure ◽  
Tensile Shear ◽  
Continuous Growth ◽  
Shear Failures

AbstractWater-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

scholarly journals Investigation into the Effect of RFSSW Parameters on Tensile Shear Fracture Load of 7075-T6 Alclad Aluminium Alloy Joints

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3397
Author(s):  
Andrzej Kubit ◽  
Tomasz Trzepieciński ◽  
Elżbieta Gadalińska ◽  
Ján Slota ◽  
Wojciech Bochnowski
Keyword(s):  
Aluminium Alloy ◽  
Shear Fracture ◽  
Load Capacity ◽  
Fracture Load ◽  
Tensile Fracture ◽  
Welding Parameters ◽  
Tensile Shear ◽  
Optimal Amount ◽  
Average Value ◽  
Type Fracture

The aim of the investigations was to determine the effect of parameters of refill friction stir spot welding (RFSSW) on the fracture load and failure mechanisms of the resulting joint. RFSSW joints were made in 7075-T6 Alclad aluminium alloy sheets using different welding parameters. The load capacity of joints was determined under tensile/shear loadings. Finite element-based numerical simulations of the joint-loading process were carried out, taking into account the variability of elasto-plastic properties of weld material through the joint cross-section. The influence of welding parameters on selected phenomena occurring during the destruction of the joint is presented. The considerations were supported by a fractographic analysis based on SEM images of fractures. It was found that there is a certain optimal amount of heat generated, which is necessary to produce the correct joint in terms of its load capacity. This value should not be exceeded, because it leads to weakening of the base material and thus to a reduction in the strength of the joint. Samples subjected to uniaxial tensile shear load showed three types of failure mode (tensile fracture, shear fracture, plug type fracture) depending on the tool rotational speed and duration of welding. Prediction of the fracture mode using FE-based numerical modelling was consistent with the experimental results. The samples that were damaged due to the tensile fracture of the lower sheet revealed a load capacity (LC) of 5.76 KN. The average value of LC for the shear fracture failure mechanism was 5.24 kN. The average value of the LC for plug-type fracture mode was 5.02 kN. It was found that there is an optimal amount of heat generated, which is necessary to produce the correct joint in terms of its LC. Excessive overheating of the joint leads to a weakening of the base metal and thus a reduction in the strength of the joint. Measurements of residual stresses along the axis specimens showed the presence of stresses with a certain constant value for the welded area on the side of the 1.6 mm thick plate.

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