Tensile behaviour of robotically-fabricated carpentry joints in natural-form log framing

The strength of a joint between the ends of one or more strips can be improved by making the contours of the joint into the shape of either the Greek letter omega or of a dovetail. From the point of view of industrial practice, it is of interest to study the behavior of these joints under stretching demands. The emergence and development of additive manufacturing processes for parts made of polymeric materials has led to the idea of conducting experimental tests to highlight the behavior of omega and dovetail-type joints during the tensile test. For the tensile testing of some test samples in which omega and dovetail joints were used, a Taguchi array of type L18 was employed, with eight independent variables, one variable with a two-level variation, and seven variables with variations on three levels. As independent variables, the type of joint, the couple of polymer materials used to make the two components of the joint, some characteristic dimensions of the joint contours, and some input factors in the 3D printing process were established. The values of average force and average displacement at the peak were considered output parameters. The experimental results were mathematically processed, determining empirical mathematical models of the second-degree polynomial type. These models highlight the influence exerted by the considered input factors on the values of the output parameters.

Using laser welding-brazing technique to join 5A06 Al alloy and ST04Z galvanized steel, the authors study the effect of adding pure powder (Si, Mg, Mn, or Zn) in the joining on the material behavior of welded joints. The results show that the microstructures, tensile behavior, and corrosion behavior of the welded joints are dependent on the powder used in the welding. An intermetallic compound (IMC) layer consisting of Fe2Al5 and FeAl3 is formed between the Al alloy and the steel, which is independent of the pure element powder used. The IMC layer with the use of Zn powder has the least thickness. The welded joints with the use of pure Mg element powder have the largest corrosion resistance.

A comparative numerical-experimental investigation on the tensile behaviour of bonded, rivetted and hybrid composite joints configurations

The microstructure, tensile properties and fracture behaviors of electron-beam welded Ti6242 titanium alloy joints were systematically investigated. The as-received alloy exhibited a typical duplex microstructure consisting of equiaxed primary α phase and laminated secondary α phase/β phase. The high cooling rate during welding resulted in substantially microstructure evolution in the fusion zone (FZ) of the joints, leading to the formation of large columnar β grains with embedded acicular α′ martensitic phase platelets. The influences of such microstructure variations on the mechanical properties and fracture behaviors at different temperatures were analyzed and discussed. In principle, the hard-yet-brittle α′ martensitic phase induced significantly strengthening of the FZ. As a result, for the un-notched specimens, the plastic deformation was concentrated to the soft base material with subsequent ductile fracture via micro-void coalescence mechanism. But for the notched specimen, in which the notch located just within the FR, cracks initiated and proceeded along the FR in a brittle manner.

Experimental study on seismic behavior of a novel plug-in self-lock joint for modular steel construction

A composite deck system composed of ultrahigh performance concrete (UHPC) and an orthotropic steel deck has been proposed to solve fatigue cracking and corrosion problems in traditional orthotropic steel deck systems. In a prefabricated steel-UHPC composite deck system, a wet joint is usually formed between two adjacent prefabricated UHPC layers. The interface between the prefabricated UHPC layer and cast-in situ UHPC is defined as a wet joint. To investigate the tensile behaviours of the wet joint, a novel tensile specimen configuration simulating the wet joint was initially proposed. The effects of reinforcement diameter and embedment length were experimentally investigated. The test results revealed that increasing the embedment length could enhance the crack resistance at the wet joint, but the influence could be neglected when the embedment length is greater than 10 db (db = diameter of reinforcement). Based on tensile tests, three-dimensional FE models were developed to simulate the tensile behaviours of the wet joint, and their accuracy was confirmed by the test results. With the validated FE model, the effect of UHPC thickness on the tensile behaviours of wet joints was investigated. Finally, specific design parameters were recommended according to the test and numerical results.

Experimental Study on Tensile and Bending Behavior of Friction Stir Welded Butt Joints of Dissimilar Aluminum Alloys

EPDM (Ethylene Propylene Diene Monomer) rubber is widely used in structural applications such as inflatable rubber dams, where joint regions are prone to failure under tensile loads. This study evaluates the effect of overlap length on the tensile behavior and failure morphology of EPDM joints bonded using a commercial vulcanized adhesive. Four overlap lengths (0.5, 1, 2, and 3 cm) were tested to assess their influence on joint strength and deformation characteristics. The results show that increasing the overlap length improves load transfer, enhances stress distribution, and increases energy absorption up to a critical value. The 2 cm overlap yielded the highest tensile strength (21.5 MPa) and peak stress (22 MPa), with failure occurring within the rubber substrate, indicating effective stress transfer. Although the 3 cm overlap produced a slightly lower UTS, it demonstrated greater deformation and the highest energy dissipation, consistent with strain-softening behavior in the elastomer. Fracture analysis confirmed that longer overlaps facilitated extended necking. Based on these findings, a 2 cm overlap was identified as the optimal configuration to balance strength and toughness in EPDM joints. This provides valuable design guidance for inflatable rubber dams and similar elastomeric applications.

In the welded joints, it becomes a common idea that the strength of weld metal is equal to or higher than it of base metal from the viewpoints of efficiency of welded joints. Otherwise, it is effective to use the weld metal whose strength is lower than it of base metal in order to prevent the initiation of weld cracking. In this report, the static tensile behaviors of the welded joints having weld metal whose strength is lower than it of base metal --so called “Soft Welded Joints” --are investigated. The “all soft welded joint” in which all weld metal are soften metal and the “partial soft welded joint” in which only a part of weld metal is soften metal were made by metal-arc welding. The main results obtained are summarized as follows : (1) The strength of the welded joints using soft weld metal whose strength is lower than it of base metal is much elevated from it of the soft weld metal itself. It is effective to use soft weld metal in a part of weld metal from the viewpoint of efficiency of strength.(2) The two standard strengths are considered as the required strength σu of welded joint, or(i) σu≥σuB(ii) σu≥ (guaranteed strength for design).The “Soft Ratio” Sr of weld metal required to guarantee the standard strength and the elongation of welded joints are considered (Table 6). When Sr (=σuW/σuB) ≥0.93, ultimate tensile strength and elongation of all kinds of soft welded joints become almost equal to those of base metal.

In this study, stress behavior of double strap joints under tensile load has been investigated numerically and experimentally. In order to strengthen the joint, the strap plates were embedded in the main adherend. In the tests, DP-810 was used as adhesive material while the steel was employed as adherend. Experiments were conducted for various embedding heights, and lengths and overlap lengths. The impacts embedding height, length and total overlap length on tensile behavior have been investigated experimentally and numerically. For confirming the experimental results, numerical analyses were carried out with finite element method. It was concluded that numerical results have good compatibility with experimental measurements. Increasing the height of the embedded cover plate resulted in decreased stress values in adhesive layer. Besides, the increase in total overlap length caused an increase in stress values.

The exoskeletal structure and tensile loading behavior of an ant neck joint

In order to study on tensile and fatigue fracture mechanism of friction stir welded (FSW) joints, the tensile and fatigue behavior of FSW joints are studied based on the microstructure and strain distribution. The large plastic deformation and fracture occurred in the thermo-mechanically affected zone (TMAZ) on retreating side in tension tests. High contents of shear texture and small angle grain boundary reduce the tensile mechanical property of TMAZ material. The fatigue weak area for FSW joints is affected by the loading condition. The strain concentration in the welded nugget zone (WNZ) and base material makes the fatigue fracture liable to happen in these areas for the FSW joints under the stress ratios of 0.1 and −0.3. When the fracture occurred in WNZ, the crack initiation mainly occurred in clusters of hardened particles, while when the fracture happened in base material, the crack initiation mainly occurred near the pit. The crack in WNZ propagated in an intergranular pattern and the crack in the other areas extended in a transgranular mode, leading to a higher crack growth rate of WNZ than of other regions.

Domination of process control parameters on tensile properties of friction stir welding of AA7075/AA6101 alloys

Effects of extreme environmental exposure conditions on the mechanical behaviour of traditional carpentry joints

Influences of TIG welding parameters on tensile behavior of dissimilar metal lap joint for low carbon steel and AA1050