Weld Rupture Research Articles

Determination of Localized Spot Weld Rupture between Inner and Outer Panels of Car Bonnet

Determination of Localized Spot Weld Rupture between Inner and Outer Panels of Car Bonnet

Determination of localised spot weld rupture between inner and outer panels of car bonnet

Determination of localised spot weld rupture between inner and outer panels of car bonnet

Experimental tests on fillet and PJP welds in CHS moment T-connections

An experimental program was developed at Dalhousie University to test various unreinforced circular hollow section (CHS)-to-CHS 90° T-connections subjected to branch in-plane bending moment with the objective of determining the effective section properties of the welded joints. Eleven specimens were designed to be weld-critical (i.e., to fail by weld rupture), and tested by applying a single quasi-static point load, laterally, to the top of each branch. An equation for the weld effective section modulus for CHS-to-CHS moment T-connections is developed, and various design formulae are assessed through a first-order reliability method analysis. The scope of this research covers fillet and partial-joint-penetration groove welded connections with 0.31 ≤ branch-to-chord width ratio ≤ 0.91, 31 ≤ chord wall slenderness ≤ 46, and 0.75 ≤ branch-to-chord thickness ratio ≤ 1.00. Recommendations are made for weld design using the “effective length approach” in AISC 360.

The blast alleviation effects of a hybrid barrier system with triple energy absorbers

Blast walls on offshore topsides are designed to protect personnel and critical equipment. The traditional design that relies on the panel as the sole energy absorber is difficult to achieve the code compliances. While studies on dual absorber system such as foam cored sandwich panels overlook the boundary effects. This study investigates the blast alleviation effects of a hybrid barrier system with triple energy absorbers (i.e. panel, foam and springs), in which the foam and springs are placed at the supports to prevent weld rupture. Accordingly, a novel design concept is proposed by using flexible supports filled with polymethacrylimide foam and rotational springs, allowing the wall to slide/rotate a certain distance/angle to release the high stresses at supports and meanwhile dissipate blast energy through material deformations. The panel deflection, energy absorption and weld rupture of the proposed system are the focal points. An analytical model based on beam vibration theory and virtual work theory has been developed, in which the boundary conditions at each support are simplified as a translational spring and a rotational spring. Finite element method has been applied to corroborate the analytical model. In addition, the interaction effects between the three absorbers have been investigated through energy absorption breakdowns. In the end, a numerical comparison study with the traditional design has been presented to demonstrate the privilege of the proposed system in minimising weld rupture risk due to the high stresses being realeased through controlled displacements and rotations at supports.

Finite Element Analysis of Weak-Axis Composite Connections Under Cyclic Loading

This paper describes a numerical study on weak-axis composite connection through the nonlinear finite element program ABAQUS. After the simulation and validation of experimental results, a total of 16 models were created to investigate the influence of the different parameters on the structural performance, and their hysteresis responses, rupture index distribution of beam flange welds were discussed in detail. The RBS connection scheme could develop extensive inelastic deformation in RBS region, thus reducing the weld rupture possibility. The thicker the concrete slab, the larger the bending moment under positive bending, and the higher the RI values at the beam bottom flange weld and also the neutral axis. The structural behavior was insensitive to the variation of the parameter reinforcement ratio as the reinforcements did not work well, and it is recommended to arrange reinforcements according to the construction requirements. Changing the weld access hole form has a little influence on the bearing capacity and rotation capacity, but the PEEQ and RI distributions are sensitive to this parameter. The design option of long access holes could provide a further means to reduce the fracture possibility of beam flange groove weld to a reasonable level, thus achieving a favorable performance of weak-axis column bending connections in a composite moment-resisting frame.

Establishing and Developing the Weak-Axis Strength of Plates Subjected to Applied Loads

When a plate is subjected to applied loads and significant out-of-plane deformation, the demand on the connection may exceed that derived from calculations due to the applied loads only. Where inelastic behavior is acceptable, the intent may be to ensure ductile behavior. For plates with fillet-welded edge connections, this can be accomplished by sizing the fillet welds to develop the strength of the plate. One specific example of this arises when a brace in a special concentrically braced frame (SCBF) is subject to compression and buckles out-of-plane. Bending of the gusset plate may demand more of the gusset plate edge connection than the calculated forces that result on the gusset edge due to the brace force specified in Section F2.6c.2 of AISC 341-16 (AISC, 2016). If not accounted for in the weld size, the uncalculated weak-axis moment on the welds from out-of-plane bending of the gusset plate might cause rupture of the fillet welds to govern the behavior of the system. The method provided in this paper is suitable to determine the minimum size of fillet welds necessary to prevent weld rupture as out-of-plane deformations occur. It can be used for fillet-welded gusset plate edges in SCBFs to satisfy the exception provided in Section F2.6c.4 of AISC 341-16.

Laser System with Adaptive Thermal Stabilization for Welding of Biological Tissues

A device for laser welding of biological tissues was developed. The main elements of the device are a laser guidance system and an adaptive thermal stabilization system. The laser solder is based on a water−albumin dispersion of single-layer carbon nanotubes (SCNTs). The properties of the SCNTs were tested using scanning electron microscopy. The surface of the weld was found to have cracks up to 10 μm in width and 150 μm in length. The cracks contained SCNT bundles <50 nm in diameter, which provided coagulation-induced sealing of the nanocomposite onto the biological tissue, thus strengthening the wound edges. Data on the welding contact temperature maintained during laser welding, the exposure time, and the corresponding weld rupture strength were obtained. The optimal weld temperature at maximal weld strength was 50-55°C. At this temperature, use of point laser welding made it possible to avoid thermal necrosis of surrounding healthy biological tissue and to obtain a welding nanocomposite with sufficient bonding strength.

Re-examination of double-angle knife shear connections

This paper reports an experimental test of 18 double-angle knife shear connections. Each specimen was monotonically loaded to failure under a combined shear load and rotation. In addition to the anticipated failure mode of rupture of welds, rupture of angles was also commonly observed. It is found that the strength of Welds B can be determined accurately by the instantaneous center of rotation method when the shear load eccentricity in the plane of the welds is taken as one-half of the leg width. The load eccentricity is not dependent on welding procedure. The test results reveal that the current U.S. design method for Welds B is extremely conservative. The failure mode of the rupture of the angles always occurred at the top of the angles along the edge of the welds. This failure is due to the combined action of connection rotation and shear load.

Cyclic behaviours of concrete-filled steel tubular columns with pre-load after exposure to fire

This paper reports experimental results of cyclic behaviours of eight concrete-filled steel tubular (CFT) columns after exposure to fire under sustained axial load. The specimens were heated by a stackable electrical furnace and blowing liquefied petroleum gas fire into the furnace simultaneously in order to simulate the real fire attack. The furnace heating can be controlled easily and safely in such a hybrid heating method using gas and electricity that the average temperature in the furnace followed as closely as possible the ISO-834 standard fire curve. After the CFT columns had been axially loaded and heated for a specified duration of time, the specimens were cooled down to room temperature according to the ISO-834 fire standard while the axial load was kept constant. Finally, the columns were subjected to lateral cyclic loading under constant axial load. The sustained pre-load led to significant residual deformations of CFT columns during the cooling phase. Two columns were found to have suffered local buckling of steel tube and three columns have suffered steel weld rupture during the fire exposure. Therefore, it is recommended that more than two vent holes or vent holes with larger diameter should be used in a CFT column and engineers should pay much attention to reasonable selection and construction of steel sections. Compared with the fire-damaged columns without pre-load and that at room temperature, the post-fire ductility and energy absorption capacity of CFT with pre-load had no obvious deterioration and the axial load level had no obvious influence on the residual strength of fire-damaged CFT. The experimental results can provide a basis for fire-damage assessment of CFT columns.

Dielectric strength of a vacuum interrupter contact gap after making current operations

Experimental results concerning the breakdown voltage and prebreakdown current of a vacuum interrupter contact gap, after making current operations, are presented. The dielectric strength of the contact gap is lowest for a switching sequence during which a making of high current is followed by a no-load contact opening. The breakdown voltage is much lower than after making operation, followed by interruption of a sufficiently high current. The basic process of breakdown initiation appears to be field electron emission from a specific structure on the contact surface, created by weld rupture.

Strength analysis of automotive seat belt anchorage

A seat belt is regarded as important equipment to keep the safety of occupants in case of frontal impact condition. However, if the seat belt anchorage does not endure load that was derived by an occupant motion during a frontal impact, the seat belt can not do the role of a restraint system any more. Thus, proper strength of a seat belt anchorage in case of a frontal impact is essential. This paper describes the modelling and analysis technique of seat belt anchorage, the seat track and the rear floor, to ensure the safety of the occupants in cases of front impact conditions. To do this, the effectiveness of the components of the seat structure was examined and the new criterion for spot weld rupture was presented. The validity of this analysis technique is shown by comparison with test results.

Interpretation of Probabilistic Structural Analysis of an Aging Passive Component

Abstract This article describes a technique to calculate the risk from failure of passive components over time, and demonstrates the technique by applying it to a weld in the auxiliary feedwater (AFW) system. It uses a modified version of the PRAISE computer code to perform a probabilistic structural analysis to calculate the probability that crack growth due to aging would cause the weld to rupture. It then uses the weld rupture probability as input to a modified existing PRA to calculate the change in plant risk with time. The results show an insignificant effect on plant risk because of the low calculated rupture rate of the weld in this particular calculation over 48 yr of service. A decreasing yearly rupture rate for this weld is calculated. This results from infant mortality; that is, most of those initial flaws that will eventually lead to rupture will do so early in life.

Failure modes for castellated beams

Abstract Previous studies of the structural behaviour of castellated beams are reviewed and a number of different possible failure modes identified. Several of these do not occur with plain webbed beams since they are a direct result of the different way in which shear is transferred through the perforated web. Examples are a Vierendeel mechanism, web post buckling due to shear and web weld rupture. Failure by either the formation of a flexural mechanism or by lateral-torsional instability are essentially similar to the equivalent modes for solid web beams. Methods for predicting the loads at which each of these types of failure occurs are evaluated against the available experimental data and the limitations in a number of these analytical approaches is discussed. It is concluded that both lateral-torsional instability and the formation of a flexural mechanism may be handled by an adaptation of established methods for plain webbed beams, providing the cross-sectional properties are those corresponding to the centreline of a castellation. Currently available methods for the determination of collapse in the other modes, while rather less accurate, are adequate for design except in the case of web post buckling due to compression.