Tensile Stress State Research Articles

Degradation Mechanism of Silver Sintering Die Attach Based on Thermal and Mechanical Reliability Testing

This article investigates the degradation mechanism of sintered silver (s-Ag) layer in silicon carbide (SiC) die attach by means of thermal shocked test (TST) and nine-point bending test (NBT). TST can thermally provide out-of-plane deformation with s-Ag die layer, whereas NBT developed by the authors can mechanically provide the out-of-plane deformation. Two types of Ag paste (NP: nanopaste and NMP: nano- and micropaste) are employed, which are sintered with 300 °C for 10 min under 60-MPa pressure for SiC die attach. TSTs are conducted under thermal cyclic loading between −40 °C and 150 °C with trapezoidal waveform for 60 min per a cycle. NBTs are conducted under cyclic mechanical loading between 0 and 300 N with triangle waveform for 3 min per a cycle at 150 °C. Scanning acoustic tomography (SAT) evaluates the die-attach delamination during TST and NBT, which starts from the edge of the die. Cross-sectional scanning electron microscopy (SEM) observation demonstrates that mechanical cracking and material aging in s-Ag layer coexist after TST under the −40 °C to 150 °C conditions only. A damage parameter (DP) proposed in this study works well to fit the delamination area ratio in the cracking and cracking-aging specimens separately after 1000 cycles. Molecular dynamics (MD) simulation and classical pore growth discussion suggest that pores can grow under only tensile stress state at high temperature, which would have given rise to the difference between the two degradation mechanisms.

Virtual element method for mixed-mode cohesive fracture simulation with element split and domain integral

We present a computational framework for mixed-mode cohesive fracture simulation based on the virtual element method (VEM). To represent an arbitrary crack path, the element splitting scheme is developed on a polygonal mesh to capitalize its flexibility in element shape. For the accurate evaluation of a crack-tip stress field and crack propagation direction, the virtual grid-based stress recovery scheme is tailored for VEM in conjunction with the maximum strain energy release rate criterion. The mixed-mode fracture examples are illustrated to validate the accuracy and robustness of the proposed computational scheme. Numerical results demonstrate that the domain integral method with the stress recovery scheme captures an accurate crack path without oscillation under the biaxial tensile stress state. Furthermore, the computed cracks using the element splitting scheme show that smooth and curved patterns on polygonal elements are in good agreement with the experimental results.

Validation of the Crack Mode-Changing Stress in Circular Tunnels Under Generalized Triaxial Tensile Stress States

In the past century, mining depths have increased profoundly from a few hundred meters to several kilometres following improvements in drilling techniques and instrumentation methods. In highly-stressed tunnels, the predominant failure mechanism of underground rock is controlled by stress-induced fractures parallel to the excavation boundaries in terms of spalling failures or, in some severe cases, a violent slab ejection that forms a V-shaped notch around the excavation walls. Such failures can seriously affect production and shut down the operation temporarily or even permanently. To better characterize, predict, and prevent these catastrophic failures, many laboratory tests and scaled model tunnels have been conducted under uniaxial and biaxial loading conditions, with limited studies also available under true triaxial stress states. This paper extends the previous studies on the impact of true triaxial loading conditions on the spalling failure in high porosity sandstone and investigates further the validation of a new Crack Mode-Changing Stress (CMCS) parameter, defined as the minimum principal stress required to change rock fracturing from splitting to a sliding failure mode. The results revealed that the minor principal stress can significantly affect the propagation of the stress-induced fractures of spalling failure along the tunnel sidewall.

Analysis of the cause of destruction of the repair welded joint of a coiled tubing pipe

The article presents the results of studies of the destruction of coiled tubing after repair with the formation of a transverse weld using fusion welding without subsequent heat treatment. The design features of the repair welded joint are considered. A description of the operating conditions of the tubing is presented – ambient temperature, working fluid temperature, pressure, working fluid flow rate, number of round trips, as well as the characteristics of the working environment containing chloride salts, hydrochloric acid solution and gaseous nitrogen (with a high percentage oxygen content). To determine the cause of the failure and identify the corresponding defects, the method of visual-measuring control, determination and analysis of the results of measurements of the hardness and chemical composition of the material of the pipe and weld, mechanical tests were used. Particular attention was paid to fracture analysis, detection of defects in the form of pores, as well as metallographic studies of the microstructure of the welded joint. The ability to use manual arc welding for pipe repair in case of failure, as well as the identification of possible defects obtained during the repair and operation of coiled tubing, allows you to more quickly repair equipment and ensure an increase in its service life, eliminating unwanted downtime. The use of additional heat treatment and well-prepared surfaces for welding by cleaning and degreasing has a significant impact on the quality of the welded joint and leads to minimal formation of defects (pores, microcracks) that affect the further operation of the equipment as a whole, operated under tensile stress conditions during repeated static bending coiled tubing.

Research of Mechanical Properties of the Aluminium Alloy Amag 6000 Under the Plane Stress State Conditions

Today's demands directly encourage to utilize the light alloy materials in industrial production. In the automotive industry, there is an increasing tendency to reduce the total weight of the car and thus also the weight of the individual car-body parts. A correct description of the material deformation behaviour with respect to the different stress states is very necessary for the own possibility to use these materials in the production. This paper describes a measurement of the mechanical properties and deformation behaviour of aluminium alloy Amag 6000 under the plane strain conditions. Thus these properties are monitored and evaluated by means of the plain strain tensile test. In this case, the plane strain is achieved by the shape concept of the testing specimen, which is loaded by the uniaxial tensile stress state using a standard testing device. The determined mechanical properties and the resulting stress-strain curves of the material under the plain stress state can be further used at defining material models for a more accurate description of the material deformation process during the sheet metal forming process.

Effect of condylar chondrocyte exosomes on condylar cartilage osteogenesis in rats under tensile stress.

Background: Functional orthoses are commonly used to treat skeletal Class II malocclusion, but the specific mechanism through which they do this has been a challenging topic in orthodontics. In the present study, we aimed to explore the effect of tensile stress on the osteogenic differentiation of condylar chondrocytes from an exosomal perspective. Methods: We cultured rat condylar chondrocytes under resting and tensile stress conditions and subsequently extracted cellular exosomes from them. We then screened miRNAs that were differentially expressed between the two exosome extracts by high-throughput sequencing and performed bioinformatics analysis and osteogenesis-related target gene prediction using the TargetScan and miRanda softwares. Exosomes cultured under resting and tensile stress conditions were co-cultured with condylar chondrocytes for 24h to form the Control-Exo and Force-Exo exosome groups, respectively. Quantitative real time PCR(RT-qPCR) and western blotting were then used to determine the mRNA and protein expression levels of Runx2 and Sox9 in condylar chondrocytes. Results: The mRNA and protein expression levels of Runx2 and Sox9 in the Force-Exo group were significantly higher than those in the Control-Exo group (p < 0.05). The differential miRNA expression results were consistent with our sequencing results. Bioinformatics analysis and target gene prediction results showed that the main biological processes and molecular functions involved in differential miRNA expression in exosomes under tensile stress were biological processes and protein binding, respectively. Kyoto Gene and Genome Data Bank (KEGG) pathway enrichment analysis showed significant enrichment of differentially expressed miRNAs in the mTOR signaling pathway. The differentially expressed miRNAs were found to target osteogenesis-related genes. Conclusion: These results suggest that stimulation of rat condylar chondrocytes with tensile stress can alter the expression levels of certain miRNAs in their exosomes and promote their osteogenic differentiation. Exosomes under tensile stress culture conditions thus have potential applications in the treatment of Osteoarthritis (OA).

Dependence of residual thermal stress in cermets on the sintering technique

The effects of representative sintering techniques on the residual thermal stress (RTS) in the as-prepared cermets were investigated using the WC-Co composites as an example. The real processing parameters of the spark plasma sintering (SPS) and sinter-hot isostatic pressing (Sinter-HIP) techniques were introduced to quantify RTS and its mechanisms. The real microstructures of cermets were used in the models for evaluation of RTS distributions in different phases. The macro-mesoscale coupled calculations indicated that during the cooling of both the SPS and Sinter-HIP processes, the WC phase of the sintered cermets has a state of compressive stress, while Co phase has a tensile stress state. The internal stress magnitude of both phases increases linearly with the decrease of temperature. There are larger temperature and displacement fields in the SPSed cermets compared to those prepared by Sinter-HIP. The stress accumulation in the SPS process is faster than that in the Sinter-HIP by 30%. The RTS in the SPSed cermets is highly concentrated at the acute dihedral angles of WC/Co interfaces, which tends to promote the face-centred cubic (fcc) to hexagonal close-packed (hcp) martensitic transformation of the Co phase.

Void Formation and Crack Propagation in a Cr–Mn–N Metastable Austenitic Stainless Steel During Bending

Microstructure evolution via deformation‐induced martensitic transformation, void formation, and crack propagation is investigated in a metastable austenitic Cr–Mn–N stainless steel for up to 90° bending using a combination of electron backscattering diffraction and parent grain reconstruction. Stress–strain heterogeneity and stress triaxiality studied using finite‐element analysis reveal that the inner and outer radii are in approximately uniaxial compressive and tensile stress states, respectively, with the outer radius showing higher values for von Mises and principal stresses and equivalent strain. Voids are observed at both austenite/α′‐martensite and α′/α′‐martensite interfaces. Parent grain reconstruction applied to the 90° bending sample reveal that the cracks at α′/α′‐martensite interfaces tend to propagate predominantly along intergranular parent austenite grain boundaries. It is also found that both intragranular and intergranular cracks in parent austenite tend to propagate between α′‐martensite child–child grains comprising the same crystallographic packets. This is the first study of its kind to comprehensively show this phenomenon. A representative example of intergranular crack propagation within a ‖normal direction (ND)‐oriented parent austenite grain is also demonstrated.

Effect of Plasma Nitriding on Structure and Properties of Titanium Grade 2 Produced by Direct Metal Laser Sintering

AbstractThis article presents the effect of an Indirect Plasma Nitriding process on the microstructure and properties of Titanium Grade- 2 samples manufactured by Direct Metal Laser Sintering Method (DMLS). It was determined, based on morphological analysis that the physical and chemical phenomena occurring at the surface during nitriding has a decisive effect on surface roughening. Phase and stress analysis shown the nitrided layer produced in a pure nitrogen at 760 °C and containing TiN + TiN0.30 + Ti2N is under compressive stress and its characteristic of a high hardness and Young Modulus as compare to Grade 2 titanium samples produced only by DMLS technique (without nitriding). Static tensile stress carried out at room temperature show that the nitrided samples containing TiN + TiN0.30 + Ti2N have much lower yield (YS0.2) and tensile strength (UTS) compared to the not nitrided samples. Tests carried out in Ringer’s solution, using impedance and potentiodynamic methods at temperatures elevated to 36.6 ± 0.3 °C to simulate human-’s’ body temperature, show that nitriding increased corrosion resistance of the alloy.

Experimental and Numerical Investigation of the Tensile Performance and Failure Process of a Modified Portland Cement

A better understanding of the tensile performance and tensile failure mechanism of cement paste is significant in preventing rock reinforcement failure. Therefore, this paper aims to reveal the tensile performance and failure mechanism of a modified Portland cement: Stratabinder HS cement. To achieve this objective, the split tensile test was conducted on specimens followed by simulating the failure mechanism numerically. The results indicated that the water–cement rate significantly influenced the tensile performance of the cement paste. When the water–cement rate increased from 0.35 to 0.42, the tensile strength declined from 1.9 MPa to 1.5 MPa. It was also observed that vertical tensile failure constantly occurred regardless of the water–cement rate. During the testing process, tensile cracks and shear cracks occurred. The increasing rate in the number of specimen cracks was dependent on the tensile stress state. Before the tensile stress reached the peak, the crack quantity increased slightly. After the peak, the crack quantity increased dramatically. During the vertical loading process, horizontal tensile stress occurred in the specimen. This horizontal tensile stress zone showed a diamond shape. The higher the tensile stress is, the larger the area of the horizontal tensile stress zone. When the tensile strength was reached, horizontal tensile stress mainly concentrated at the vertical centre of the specimen. This finally led to tensile failure of the specimen. This paper indicated that the water–cement rate was the key factor in evaluating the tensile strength of the Stratabinder HS cement.

Mechanical Response Analysis of Asphalt Pavement Structure with Embedded Sensor

Long-term and real-time monitoring of asphalt pavement can be carried out by using embedded sensors to perceive and predict structural damage during pavement operation period, so as to avoid sustained development of damage. However, the influence of embedded sensors on the mechanical properties of asphalt pavement structure and the structural optimization of sensing elements needs to be further studied. Based on the finite element numerical simulation method, static load model and three-point bending test mode were conducted with three “pavement-sensor” coupling model without sensor, with embedded I-shape sensor, with embedded corrugated-shape sensor. Three simulated conditions were studied comparatively of the sensing element embedding effect on the mechanical response of asphalt pavement structure. Results show that the sensing elements embedded with the two structures have a certain influence on the stress and strain field of asphalt concrete. Within the range of 60–100 mm the asphalt mixture is in a state of tension; the stress values increase with depth and show a maximum tensile stress state at the bottom of the beam. In the compression zone, the strain of the I-shape sensing element embedded is closer to that of the strain without the sensing element embedded. Along the axis of the two sensing elements, the axial strain of the I-shape sensing element is smoother and uniform, which ensures the deformation coordination in the road state. The optimal length L of the sensing element is 14 cm, the diameter φ of the sensor is 10 mm, and the I-beam length GL is 10 cm.

Effects of nitrogen flux and RF sputtering power on the preparation of crystalline a-plane AlN films on r-plane sapphire substrates

A-plane aluminum nitride (AlN) with high quality is crucial to fabricate high-performance non-polar deep-ultraviolet optoelectronic devices. In this work, we prepared crystalline a-plane AlN films on r-plane sapphire substrates by combining reactive magnetron sputtering and high temperature annealing (HTA). The effects of N2 flux and radio frequency (RF) sputtering power on the crystal quality, the surface morphology and the in-plane stress state of a-plane AlN films were comprehensively investigated. The results suggest that the properties of high temperature annealed a-plane AlN (HTA-AlN) films positively depend on the initial states of the sputtered AlN (SP-AlN) films. Increasing the N2 flux or the RF sputtering power can improve the crystalline quality of SP-AlN films by reducing the kinetic energy of deposited particles, which facilitates a-plane AlN deposition. A higher N2 flux smoothens the surface morphology due to the relieved bombardment effect, which is confirmed by the enlarged in-plane tensile stress state. However, a higher sputtering power leads to a rougher surface because of the accelerated deposition rate. With optimized sputtering parameters, a high-quality a-plane HTA-AlN template was obtained with full width at half maximum values of (11–20) plane x-ray rocking curves as low as 1188 and 1224 arcsec along [0001] and [1–100] directions, respectively. The surface presents an ordered stripe-like morphology with a root-mean-square value of 0.79 nm. Our work provides a convenient and effective strategy to prepare high quality a-plane AlN templates and accelerate the versatile application of non-polar deep-ultraviolet light-emitting diode devices.

Resetting of zircon inclusions in garnet: Implications for elastic thermobarometry

Abstract Elastic thermobarometry of host-inclusion systems for back-calculating pressure (P) and temperature (T) conditions of inclusion entrapment relies on the assumption that the hostinclusion rheology is purely elastic. In this study, we have explored both the elastic and non-elastic behavior of zircon-in-garnet (ZiG) systems by in situ Raman spectroscopy at high T and ambient P. We show that upon heating, plastic relaxation takes place immediately after the zircon inclusions experience tensile stress conditions with respect to a free crystal at the same T. On subsequent cooling, the inclusions develop a new stress state, and thus the inclusion pressures have been reset from those corresponding to their original entrapment. Resetting of inclusion pressures therefore strongly depends on the exhumation P-T path. This explains why elastic thermobarometry using ZiG systems is reliable when applied to low-P high-T rocks where the cooling path after inclusion entrapment passes quickly into the compression domain of the inclusion. On the other hand, high-P rocks exhumed along quasi-isothermal paths take zircon inclusions into the tensile domain where they are reset until significant cooling commences at low P. ZiG systems in ultrahigh-P rocks therefore commonly indicate pressures on clockwise exhumation paths instead of the conditions of original entrapment.

Stress-Affected ORR on Stainless Steel

Oxygen reduction reaction (ORR) is an important cathodic reaction that often drives galvanic corrosion. In atmospheric environments, this reaction is responsible for accelerated corrosion from enhanced transport associated with discontinuous electrolytes. In load bearing structures, galvanic couples are subject to mechanical stresses that often necessitates these dissimilar metal unions. Greater understanding of mechanical stress effects on fundamental reactions of galvanic corrosion, such as ORR, is important from a forecasting perspective for improved prediction of component lifetimes and service requirements. Furthermore, extension of this behavior to confined, concentrated electrolytes is important to understand stress effects in atmospheric environments.This work reports the impact of tensile stress upon oxygen reduction reaction (ORR) for stainless steel fastener materials. Chronoamperometry was used to observe and quantify the influence of tensile stress profiles on ORR under NaCl droplet electrolytes. NaCl was utilized as a seawater proxy at concentrations of 0.6 M NaCl and 4.6 M NaCl, the latter corresponding to 80% relative humidity, which is near the deliquescence point for NaCl. The ORR current was shown to increase with tensile stress and displayed reversible behavior with simple stress profiles. Deoxygenated experiments were performed to isolate ORR contributions from oxide dynamics. Details of current transients during strain ramping are used to demonstrate these features are distinct from the ORR current shift observed during static tensile stress. Polarization experiments were performed during static tensile holds in the elastic and plastic regime for greater insight of stress effects on reduction kinetics. EIS and Mott-Schottky experiments were conducted to gain insight into the oxide behavior.

Hydrogen Embrittlement Behavior of Plastically Pre-Strained and Cathodically Hydrogen-Charged 316H Grade Austenitic Stainless Steel

In this work, the effects of electrochemical hydrogen charging of 316H grade austenitic stainless steel were investigated in order to characterize its hydrogen embrittlement (HE) resistance. The as-received 316H material was in a fully recrystallized (solution-annealed) material condition. The susceptibility to HE of the studied material was evaluated by determination of the embrittlement index from the results of conventional uniaxial tensile tests of nonhydrogenated and hydrogen-charged test specimens. The study was focused on the effects of two selected plastic pre-strain levels of tensile specimens on their resulting HE resistance. The selected pre-strains corresponded to the tensile stress conditions within the “yield stress–ultimate tensile strength” (YS–UTS) range and directly at the UTS point. The obtained embrittlement indices for the presently used pre-straining and hydrogen charging conditions indicated that the HE of the studied material states was small. However, it was revealed that the observed degradation of deformation properties of plastically pre-strained and hydrogen-charged materials was mainly caused by gradual plasticity exhaustion due to tensile straining, which well correlated with the observed effects indicated by electron backscatter diffraction analyses and indentation hardness measurements.

Comparative Studies on Shear Failure Behaviors of U71Mn Rail Steel at High Strain Rates Using Hat-Shaped Specimens

Abstract The shear failure behaviors of U71Mn rail steel are investigated by quasi-static and dynamic compression tests utilizing two different hat-shaped specimens: S1 which combines shear and compressive stress states and S2 which combines shear and tensile stress states. A split Hopkinson pressure bar is used to acquire shear stress–strain curves at various initial temperatures and shear strain rates, and it is found that a lower shear strain rate is observed in hat-shaped specimen S1 than that in hat-shaped specimen S2 under the same impact pressure. Scanning electron microscopy is employed for observing the microstructures of specimens. The results indicate that the hat-shaped specimen S1 is difficult to form voids and dimples. Moreover, as far as the hat-shaped specimen S2 is concerned, the number of voids reduces with the rising shear strain rate, and no voids appear on the fracture surface at the shear strain rate of 36,000 s−1. Furthermore, the creation of voids is aided by a rise in initial temperature. The factors affecting the formation of adiabatic shear bands are explored based on the numerical simulation, which suggests that the magnitude of the temperature gradient plays a crucial role in the generation of adiabatic shear bands.

Electrochemical/Microstructural Studies on the Corrosion of Prestressed Steel Strand in Concrete with Naturally Ingressing Chlorides

The occurrence of environmentally assisted cracking (EAC) is as dependent on the aggressiveness of the environment as the susceptibility of the material and the presence of static tensile stresses. However, the influence of the environment has not been adequately considered in past investigations on EAC mechanisms of prestressing strands. This study utilizes various characterization techniques to evaluate the surface/bulk deterioration of corroded pretensioned concrete (PTC) specimens after natural chloride exposure (by diffusion through cover concrete). Corroded strands in two PTC prism specimens (3,000 mm × 150 mm × 200 mm) were characterized using electrochemical impedance spectroscopy (EIS) and other microanalytical techniques. The EIS and scanning electron microscope (SEM) images obtained after 1 y and 2 y of exposure revealed a negligible residual protectiveness of the passivated surface (although the concretes possessed high resistivity). Raman spectra, SEM, and x-ray computed tomography images of extracted corroded strands also provided unique insights into the pattern of corrosion propagation in PTC systems subjected to realistic chloride exposure. Microcracks in the bulk metal beneath flat-bottomed corrosion pits revealed the possible EAC at low chloride levels expected in service (&amp;lt;0.6% by weight of binder). The findings serve as a basis to define chloride-induced passive-to-active transition as the end of risk-free service life of PTC structures, and for considering it as the limit state for both service life design and corrosion assessment to avoid the onset of EAC.

A multifunctional rock testing system for rock failure analysis under different stress states: Development and application

The stress state in a rock mass is complex. Stress redistribution around underground excavation may lead to various failure modes, including compressive-shear, tensile-shear, and tensile failures. The ability to perform laboratory tests with these complex stress states is significant for establishing new strength criteria. The present paper introduces a new rock testing system with “tensile-compressive-shear” loading functions. The device includes bi-directional and double-range hydraulic cylinders, auxiliary loading equipment, and roller rows that can perform direct compressive-shear tests, direct tensile tests, and direct tensile-shear tests. The testing system provides maximum vertical and lateral loading forces of 2000 kN and allows testing cubical rock specimens with dimensions of 0.5 m × 0.5 m × 0.5 m. The performance of the testing machine was evaluated by testing a rock-like material based on cement mortar under compressive-shear, tensile, and tensile-shear stress states. The failure process and deformation characteristics were monitored during loading using acoustic emission (AE) transient recorder, piezoelectric AE sensors, a high-speed camera, and a thermal infrared camera. The failure mechanism was investigated by analyzing AE counts, AE amplitude, strain, and temperature changes on the rock specimen surface. The test results confirmed that the testing system could successfully simulate the abovementioned stress path. The AE counts and amplitude responses were influenced by different failure modes. The temperature response during the compressive-shear test indicated the development of a high-temperature band on the rock specimen surface. In contrast, a negligible temperature change was observed during the tensile and tensile-shear tests. The newly developed multifunctional rock testing system allows laboratory tests under various failure modes. The monitoring results of multiple variables during rock failure tests provide valuable information on failure characteristics. • Develop a novel rock testing system with tensile-compressive-shear loading function. • Investigate the failure behavior of rock-like specimens under different stress states. • Analyze the various attributes response characteristics in different failure modes.

Stress Dependence on Relaxation of Deformation Induced by Laser Spot Heating.

This paper deals with a non-destructive analysis of residual stress through the visualization of deformation behaviors induced by a local spot heating. Deformation was applied to the surface of an aluminum alloy with an infrared spot laser. The heating process is non-contact, and the applied strain is reversible in the range of room temperature to approximately +10 °C. The specimen was initially pulled up to elastic tensile stress using a tensile test machine under the assumption that the material was subject to the tensile residual stress. The relaxation behaviors of the applied strain under tensile stress conditions were evaluated using contact and non-contact methods, i.e., two strain gauges (the contact method) and a two-dimensional electronic speckle pattern interferometer (non-contact method). The results are discussed based on the stress dependencies of the thermal expansion coefficient and the elasticity of the materials.

Investigation of block shear strength of high strength steel bolted connections

This study presents an experimental and numerical investigation of block shear strength of high strength steel (HSS) bolted connections under double shear. A total of 16 HSS (grades Q690 and Q960) and eight mild steel (MS) (grade Q345) bolted connection specimens with various geometric configurations were tested and failed in block shear failure mode. The test and finite element (FE) analysis results confirmed that the block shear failure is a combination of fracture of the net tension plane and yielding of the effective shear plane, which is located between the net and gross shear planes. The effects of material properties (such as ductility and tensile-to-yield strengths ratio (fu/fy)) of steel materials on the block shear strength were comprehensively investigated based on the validated FE models. It was found that the tensile stress across the net tension plane could be fully developed irrespective of the steel grade due to effective stress redistribution along the net tension plane and the beneficial effect of the biaxial tensile stress state. However, the shear stress magnitude along the shear plane is influenced by the ductility and fu/fy ratio of steel materials and the length of the shear plane. The low ductility and fu/fy ratio of HSS materials did not allow for effective stress redistribution along the long shear plane and the shear yielding could only partially develop along the shear plane at the ultimate state. For the HSS specimens with short shear planes, the shear stress could develop up to the shear yield strength in general. Finally, the accuracy of the existing design equations in various design codes (i.e., prEN 1993–1–8: 2021, ANSI/AISC 360–16, and CSA S16–19) and relevant literature for predicting the block shear strength of bolted connections was evaluated and design recommendations were provided.