Tearing Failure Research Articles

Seismic performance of external diaphragm joints of steel beam-to-CFST column encasing fiber reinforced polymer confined UHPC core

A novel composite column was introduced by integrating a concrete-filled steel tube column encasing a Fiber Reinforced Polymer (FRP) confined ultra high performance concrete (UHPC) core. In this paper, the seismic performance of four SCF-UHPC composite column-to-steel beam connections using external diaphragm joints was experimentally investigated under the quasi-static test. All specimens failed due to the formation of plastic hinges at the beams and the tearing failure on the beam flanges at the plastic hinge zone. The local buckling at the column end and the panel zone was observed for the specimens receiving the higher axial compression ratio. The increase of FRP tube thickness is more effective in improving the ductility and energy dissipation capacity of the joints than increasing the UHPC core diameter. On the contrary, increasing the UHPC core diameter led to better resistance to the shear deformation of the panel zone. The proportion of shear deformation to the total deformation of the panel zone and the strain distributions were investigated to determine the effect of each component. The composite column in the panel zone mainly carried the compression-bending effort, and the external diaphragm mainly took the shear effort. All joints were eventually classified as semi-rigid type joints, according to the initial rotational stiffness.

Association analysis between the distribution of surface physical characteristics and bonding performance of carbon fiber composites

AbstractEffects of plasma treatment distance on the adhesion properties of carbon fiber composites were investigated, and the association between the distribution of surface physical characteristics on the composites and their bonding properties was discussed. After plasma treatment at different distances, surface morphology of the bonding area was obtained and the roughness distribution model was established. The change in surface physical characteristics directly influences the wettability of the bonding surface and the tensile shear strength (TSS) of the bonded components. When the TSS showed an increase by 19.47% at the treatment distance of 15 mm, metallographic images indicated that the bonding layer was integrated with the composites and the joint in the component was dominated by cohesive failure. When the TSS showed a decrease by 30.72% at the treatment distance of 5 mm, metallographic images indicated that voids and delamination were introduced in the bonding layer and fiber tearing failure mode appeared in the plasma etched area. Moisture‐heat resistance of the bonded components was also considered and a noticeable increase in water absorption was observed in the case of excessive treatment at the distance of 5 mm, which was also related to the distribution of physical characteristics induced by the plasma treatment.Highlights Surface characteristic distribution of plasma‐modified composites was analyzed. State of resin and fibers on composite surface varied with the treatment distance. Semi‐annular plasma treatment traces appeared in the roughness distribution. The high roughness in the distribution played a key role in bonding properties. Performance degradation due to close treatment was also distribution‐dependent.

Experimental investigation on withdrawal resistance performance of nails in southern pine

The objective of this study is to evaluate the structural performance and withdrawal capacity of three types of nails embedded in southern pine (SP) framing members. Pull-out tests on 430 specimens were conducted until complete withdrawal occurred. Representative variables derived from practical wall-to-wall or wall-to-floor connections were considered, including nail type, nail diameter, embedment length, and nail direction. Results reveal that the failure modes of specimens depend on nail shank roughness. Smooth shank nails (SSNs) and concrete nails (CNs) mainly experience nail-wood interface sliding and wood fiber tearing failures, while zinc-coated helically threaded nails (ZHTNs) exhibit wood fiber shearing and tearing failures. As expected, the ultimate withdrawal capacity increased with greater embedment length, with the highest capacity of nails in the perpendicular-to-grain direction, followed by parallel-to-grain. The withdrawal load-slip relationships of nails in SP consist of three stages: linear-elastic rise, plunge, and failure stage for SSNs and CNs, while ZHTNs exhibit elastic-plastic behavior during the second phase. The modified Rafi model suggested in this study can be used to translate the withdrawal bond-slip relationships of nails in SP. Finally, a withdrawal resistance calculation equation for SP was put forward and validated, showing an average difference of 10.33% between theoretical and experimental values.

A Comprehensive Investigation of Deep Drawing Processes for a 2-Inch Diameter Dop-pipe Cap: Numerical and Experimental Analysis

The persistent challenges in material forming processes arise from recurrent issues encountered during the deep drawing process, particularly involving cracks and deviations from standard thickness dimensions. This article investigates the deep drawing process using both experimental and numerical methodologies. The experimental approach employs a 40-ton capacity power press machine, while the numerical method utilizes the ABAQUS student version software. SPCC-SD (JIS G3141) is the selected material for producing a Dop-pipe 2-inch diameter pipe cap in both approaches. Noteworthy findings include the highest positive and negative correlations observed in elements E 46 and E 48, with values of 0.715 and -0.933, respectively. Minimal disparities, averaging around 4.6% for all components, were evident between the experimental and numerical methodologies. The numerical approach yielded predictive results identifying potential issues in elements E 47 and E 48. This observation did not reveal instances of tearing failure but instead showcased an increase in thickness due to a higher axial force between the dies and punched-in components. The study successfully and accurately predicted product thickness for all components, presenting a contrast with outcomes obtained through the experimental method. Furthermore, this research advances the deep drawing process, extending its applicability to broader material forming applications and ultimately enhancing overall production process efficiency.

An effective micro-arc oxidation (MAO) treatment on aluminum alloy for stronger bonding joint with carbon fiber composites

The micro-arc oxidation (MAO) treatment was used in this study to modify aluminum (Al) alloys to improve bond strength with carbon fiber reinforced polymer (CFRP). Various porous surfaces of Al alloy with better hardness, roughness and wetting were created. Void defects were reduced via using resin pre-coating (RPC) technique to guide high-viscosity epoxy into the holes, CNTs fiber bridging was constructed to improve bonding interface and epoxy adhesive layer. Combined treatments of “Na2SiO3 + KOH solution” MAO, RPC and introducing CNTs on Al alloy surface yielded 21.34 MPa, up to 156.1% increment over base strength. Original de-bonding failure on Al alloy surface was altered into dominant fiber tearing failure of CFRP composites, indicating the reinforced bond strength and stronger adhesive joint. MAO was the first try and proved as a feasible treatment for bond strength improvement, which could provide an alternative to manufacture high-performance Al-CFRP composites in industrial production.

Shear mechanism and strength calculation of steel shear keyed dry joints in precast segmental bridges

Precast concrete segmental bridges (PCSBs) are prone to weakness at the joints. To ensure accurate positioning and effective force transmission between segments, steel shear keyed joints were designed in the present study. A comprehensive investigation was also conducted into the shear performance of such joints, drawing on existing experimental research and theoretical analysis, so as to facilitate more comprehensive understanding of the shear mechanism and calculation methods involved. The results reveal that the steel shear keyed joint effectively transmitted shear force through the contact pressure between the steel key and concrete, aided by confining pressure. The steel keyed joint was also found to possess high shear capacity and exhibit good ductility. A mechanical model of the steel shear keyed joint was constructed, and the shear mechanism and failure modes were revealed, including shear failure of the steel key, local compression failure of concrete, and tearing failure of concrete. Finally, the present authors suggest that the shear failure of the steel key should be used as the basis for the shear resistance design of steel shear keyed joints, which can be calculated according to the formula ( The strength of concrete around the steel key should also be checked.

Damage constitutive model and numerical simulation of in-plane tear failure for architectural fabric membranes

Tearing failure is the key factor affecting the safety of tension fabric structures, but there is a lack of material damage models and numerical methods needed to simulate tearing failure. This paper investigates the macroscopic damage model of architectural fabrics and the numerical simulation method for its tearing failure. Firstly, based on the incremental stress update scheme, theoretical descriptions of the material model considering the nonlinear elastic damage behavior are presented. Then, the influence of stiffness softening laws and the mesh schemes are investigated, and the advantages of easy implantation and good precision of the proposed model are validated by comparison with the cohesive element model embedded in ABAQUS. Compared with the experiment results and theoretical model, the predicted results are in good agreement for various crack length cases, and the nonlinear variation mechanism of tearing residual strength is revealed. Also, the effect of the tensile strength and fracture energy are discussed, and it is found that the crack tip blunting effect causes the linear elastic fracture mechanics not applicable.

Structural behaviour of Cold‐Formed Steel back‐to‐back welded sections subjected to longitudinal shear

AbstractThe current study focuses on understanding the behaviour of flare v‐groove welds on back‐to‐back connected Cold‐Formed Steel welded sections (G300) subjected to longitudinal shear. A novel welding technique called Cold Metal Transfer (CMT) welding was used for fabrication with copper‐coated steel welding wire as a filler metal (ER70S‐6). This mode of welding has the advantage of controlled material deposition compared to the spray or globular mode of welding. Lap shear tests were carried out on unlipped channels including thickness of the weld, and length of the weld. The weld geometry was observed under an optical microscope after polishing and chemical etching of the weld cross‐section, as American Iron and Steel Institute (AISI) design standard provides no specification on thickness of flare v‐groove welds for CMT welding process. In general, the lap shear specimens failed in plate tearing failure mode and brittle fracture of weld at the weld contours. Additionally, the appropriateness of AISI's shear design strength equations for flare v‐groove welds was verified and preliminary design guidelines are provided addressing the lacunae in AISI design standard.

The influence of welding speed on nanosecond laser welding of AZ31B magnesium alloy and 304 stainless steel

Nanosecond pulse laser welding was performed on AZ31B magnesium alloy and 304 stainless steel to investigate the impact of welding speed on the joining process. The temperature field of the magnesium/steel laser welding process was simulated using COMSOL software. The findings revealed that a welding speed of 10 mm/s resulted in significant spattering and larger porosity defects in the joint due to excessive heat input. However, when the welding speed was increased to 30 mm/s, these defects disappeared, and the porosity decreased to a minimum, leading to an increased bonding area at the interface. As the speed increased, the heat input decreased, making it more challenging for the porosity to escape from the molten pool and resulting in the formation of larger pores. The shear force test results indicated that the highest shear force was 298.7 N at a welding speed of 30 mm/s. The reduction in porosity and greater penetration depth of the magnesium alloy contributed to the desired mechanical performance. Additionally, the fracture modes were classified as button pullout failure (BPF), base material tearing failure (BTF), and interface failure (IF). The outermost weld seam served as the initial fracture path for both BPF and BTF modes, with BTF ultimately fracturing in the steel base material during tearing. Oxide inclusions, porosity, and the angle of distortion contributed to the fracture path of IF.

3-ply self-drilling screw connections for centre-sheathed steel shear walls

Design provisions for the shear resistance of double shear (3-ply) cold-formed steel screw connections are not provided by the existing CSA S136 and AISI S100 Standards. The resistance of the mid-ply layer of screwed double shear connections was investigated to determine whether the use of the bolt bearing provisions was a reasonable substitute. Forty-eight individual normal ductility steel connections with fastener diameters between 4.17 mm and 5.49 mm and inner sheet thicknesses between 0.36 mm and 1.09 mm, as used for previously constructed centre-sheathed shear walls, were tested. Bearing damage and a combination of bearing and tearing failure were observed. The strengths of the connections tended to increase as displacement progressed due to expansion of the bearing area. When a displacement limit of 6.35 mm was enforced, the tested strengths of the screw connections were a reasonable match to the bolt bearing provisions. The resistance factor ϕ for the double shear screwed connections was identified to be 0.54 (LRFD) and 0.43 (LSD).

Experimental and numerical investigation of the prefabricated steel–concrete open-web composite floor with embedded chords

To reduce the height and improve the installation efficiency of novel prefabricated steel-concrete open-web composite floor (SOF), a developed SOF was proposed. A full-scale (9.0 m × 9.0 m) laboratory test and detailed parametric finite element (FE) analysis were conducted to explore the load-bearing capacity, typical failure modes, load-displacement relationship, and strain variations at key locations of the structure. The experimental findings indicated that the concrete slab and upper chord exhibited good composite behavior, and no interfacial failure was observed between the concrete slab and the T-section. The joint diaphragm welds failed in tension due to insufficient capacity of the bottom chords, while web members continued to transfer axial tension, resulting in local tearing failures outside the plane. Further finite element analysis illustrated the damage evolution of the concrete slab and steel grids. Moreover, the mechanical properties of the structure were found to be relatively insensitive to the changes in geometric parameters across the different locations. The conclusions drawn from this study can be utilized as reference for the design and analysis of spatial composite slab structures.

The mechanical performance evaluation of recombinant bamboo with weakened metal connections under low-cyclic loading

ABSTRACT Tearing failures often occur at the bolt position of the recombinant bamboo beam under a large bending moment and shear force due to its poor compressive strength perpendicular to the grain. In this study, three H-shaped weakened connections were designed to explore the mechanical performance of the recombinant bamboo frames under low cyclic loading. The weakened forms of the web were selected as variables, including elliptical, rhombic, and arc holes. Load-displacement hysteresis curves, skeleton curves, stiffness degradation, ductility analysis, equivalent viscosity damping coefficient, and failure modes of the recombinant bamboo frame with three weakened connections were compared and analyzed. The results show that the weakened connections achieved the purpose of the outward movement of the plastic hinge. The moment and shear force will lead to the stress concentration of connection with the rhombic hole, and buckling failure of connection with the arc hole is easy to occur. Comparatively, the ultimate bearing capacity and energy-dissipating capacity of connection with the elliptical hole are the best among the three weakened connections. In conclusion, the weakened shape and position have a great influence on seismic performance.

Research on mechanical clinching process for dissimilar aluminum alloy sheets with inclined surface

In this work, dissimilar aluminum alloy sheets with inclined surfaces were joined by flat-clinching process. Three types of aluminum alloy sheets, namely AA1060, AA5052 and AA6061, were employed to produce six types of clinched joints. Further, the mechanical properties of all clinched joints were investigated experimentally. Moreover, the failure evolution process and energy absorption capacity of clinched joints under static loading were also evaluated. From the experimental results, more outstanding performance of mechanical properties was observed for the joints made by the upper sheet with higher tensile strength. A new type of failure mode, never reported in previous studies, appeared in failed AA6-1 joint, which is termed as pull-off tearing failure mode. It is found that both in terms of safety and bearing load the material with higher tensile strength is more suitable for the upper layer when joining dissimilar aluminum alloy sheets with inclined surface by flat-clinching process. The process proposed in this work is particularly suitable for the joining the thick sheet and for the industrial occasion which requires a flat surface on both sides of the connected sheets after joining. This work is contribute to expand the case in industrial practice of the mechanical clinching process and improve the joined quality of the clinched joint.

Deformation mechanism analysis of steel artificial controllable plastic hinge in prefabricate frame

The concept of structural recoverability has become a vital performance objective in structural seismic design. A novel performance-recoverable beam-column connection device, steel Artificial Controllable Plastic Hinge (ACPH), was proposed to achieve structural function restoration after earthquakes. The bending-shear decoupled prefabricated ACPH is composed of a pin-hinged connection bearing shear force, and two sets of replaceable energy dissipation plates providing flexural resistance. The weakening ratio effect of the energy dissipation plate on the ACPH seismic performance was experimentally explored by three specimens. The results indicated that the ACPH had excellent hysteresis behavior, as well as superior ductility. Moreover, the ACPH yield mode was the compression yield of the energy dissipation plate. The failure mode was the tearing failure in the weakened area of the energy dissipation plate. The pin-hinged connection was barely deformed throughout the working process, which guarantees the ACPH repairability and attains the goal of ACPH damage control. Besides, based on the component method, the deformation model and deformation calculation formula of ACPH were proposed, which considered the deformation effects of the bolt rod, the installation gap, the energy dissipation plate, the end plate of the energy dissipation, and the installation clearance of bolts. The formulas of ultimate moment bearing capacity for the ACPH were put forward based on the thin plate theory.

Crashworthiness Analysis of Square Aluminum Tubes Subjected to Oblique Impact: Experimental and Numerical Study on the Initial Contact Effect

This study investigates the crashworthiness behavior of square aluminum thin-walled tubes subjected to both axial and oblique impact loading, emphasizing the effects of crushing angle and initial contact between impactor and tube on the plastic collapse initiation and energy absorption capacity. A parametric study in crushing angle is conducted until 15°, while the two examined types of initial contact between impactor and tube consist of a contact-in-edge case and a contact-in-corner one, aiming to capture the effect of initial contact on both plastic collapse and energy absorption. Both experimental quasi-static tests and numerical simulation via finite element modeling in LS-DYNA software are carried out for the evaluation of the crushing response of the tested tubes. The 5° oblique cornered crushing revealed the greatest energy absorption, reflecting the most efficient loading case as significant tearing failure occurred around the tube corners in axial crushing due to a higher peak crushing force, while the increase in crushing angle caused a drop in energy absorption and peak force regarding the oblique loading. Finally, an initial contact-in-corner case revealed higher energy absorption compared to both axial and edged oblique loading, while peak force showed a slight decrease with crushing angle in that case.

Influence of ultrasonic application on soybean aqueous extract based composite edible film: Characterization and their food application

In this study, a soybean aqueous extract-based composite film was developed by incorporating beeswax, clove essential oil, and span-20 via ultrasonication. The effect of ultrasonication power level (0–600 W) on the rheological properties of the film forming solution (FFS) and important film properties such as water vapor permeability, tensile strength, elongation at break, and opacity was evaluated. It was found that ultrasonication treatment until a power level of 400 W at a constant treatment condition of 15 min and a frequency of 20 kHz improved barrier (water vapor permeability: 2.91 × 10−10 g m/m2·Pa·s) and mechanical properties (tensile strength: 2.53 MPa). Ultrasonication considerably reduced the apparent viscosity of FFS from 1.32 Pa s (control) to 0.188 Pa s (600 W) and improved the flow behavior. The smooth and homogenous surface obtained in SEM analysis validated the enhanced properties obtained for ultrasonication treated films. Model fitting of moisture sorption data of the experiments indicated that the GAB model is best suited to predict the moisture uptake behavior of developed films at all selected temperatures (25, 35, and 45 °C). Sealed samples exhibited a tearing failure during testing with a seal strength value of 59.16 N/m. A qualitative biodegradation test resulted in the degradation of films within 12 days, making them an eco-friendlier packaging option. Application of the developed film as a packaging material for muffins showed that soybean aqueous extract-based film could maintain the moisture content and textural parameters of muffins for up to six days under ambient storage.

Ductile tearing criteria and failure probability estimation of hydrided Zircaloy-4 cladding under axial loads

Ductile tearing criteria and failure probability estimation of hydrided Zircaloy-4 cladding under axial loads

Failure properties of flexible composite under trouser-shaped tests

The failure properties of trouser-shaped tests on flexible composite called Uretek-3216LV were studied by experiment and theory. Based on the failure mechanical behavior of the trouser-type tests, theoretical model of the three stages (displacement, fiber stretching, and fiber breaking) were established. In the model, a spring system including the tail, tear del, and the fiber elongation is introduced to characterize the mechanical behavior of the displacement stage and the fiber stretching stages. Based on the strain wave model, the failure model of fiber breaking stage is established. Based on the trouser tearing tests and failure model, the trouser-shaped failure performance of flexible composites was analyzed in detail.

Experimental study on axial compression buckling of glass fiber reinforced plastics solid pole with circular cross-section

Glass fiber reinforced plastics are widely used in civil engineering because of their advantages such as light weight, high strength, good pollution resistance, and corrosion resistance. This study investigated the buckling bearing capacity, failure characteristics, and slenderness ratios of GFRP solid bars with circular cross-sections subjected to axial compression. A total of 18 specimens were categorized into six groups. The slenderness ratios ranged from 57 to 123. It was found from experiments that the instability mode of the specimens was extreme point instability, and a bearing capacity platform phenomenon was observed when overall lateral instability occurred. The failure mode was axial and transverse tearing failure of the material in the middle of the specimen. During buckling, the tensile side was transformed from the compression of the resin matrix to tension in the fibers. The elastic modulus of glass fiber was much lower than that of the resin matrix. After tension occurred, increased deformation led to a rapid increase in lateral bending, which resulted in the phenomenon of the bearing platform. At ultimate deformation, brittle failure of the specimen occurred. The buckling load of the specimen decreased sharply with an increase in the slenderness ratio, and stress ratios decreased from 34.95% to 6.73%. It is suggested that the slenderness ratio not exceed 80. Finally, based on experimental results, a practical method for calculating the stable bearing capacity of solid GFRP poles is proposed.

Tearing behaviors of polytetrafluoroethylene coated fabric under uniaxial in-plane tearing tests

This study conducts alternative-basic-angle trapezoidal tearing and single-edge notch tearing tests on a polytetrafluoroethylene coated woven fabric, where the two methods are related through the basic angle of a trapezoid. The tearing process and failure modes are carefully examined, and load–displacement curves and tearing strength are analyzed. The tearing process comprises three stages, which are distinguished photographically or in different load–displacement curve sections. Corresponding to these stages, failure modes can be classified into three parts with varying extension directions. The effect of the basic angle is clearly illustrated. As the angle increases, three stages and parts appear in sequence; the tearing strength increases, but the larger one changes from weft to warp. The relationship between the tearing process and tearing strength is described. The three stages correspond to the increase in tearing strength, occurrence of the maximum tearing strength, and failure. Because the single-edge notch tearing method is more complex and important, it is the method that is studied mainly. Digital image correlation equipment is used to observe the strain distribution at the crack section. Moreover, the applications of four frequently used models are investigated. The results indicate that Thiele’s empirical formula offers the best simulation among the three tearing strength prediction models, and the theoretical stress distribution model also provides good simulation. Furthermore, a numerical simulation is conducted. The critical tearing strength and load–displacement curves before tearing initiates acquired through the simulation and test agree well. All results may provide basic data for future improvements in design theories.