Search Results (37)

In this research, we assess the feasibility of employing hybrid friction stir channeling (HFSC) to produce composite panels that combined an 8 mm thick AA6082-T6 aluminum alloy and 5 mm thick glass-fiber-reinforced Noryl GFN2. HFSC is an innovative solid-state technology that combines both friction stir joining and channeling characteristics, which enable the generation of integral internal channels while joining different components. A parametric study was outlined to explore the effects of the travel speed, probe length, and tool plunging on the resulting composite panels. The resulting composite panels were subsequently subjected to a comprehensive analysis encompassing exterior ceiling quality, internal channel, and joining interface morphology. Depending on the processing parameters, the geometry of the channels was found to be quasi-rectangular or quasi-trapezoidal, with significant variability on cross-sectional area, resulting in hydraulic diameters ranging from 1.2 to 2.9 mm. The joining interface was characterized by a concavity of aluminum that was extruded downwards into the polymeric molten pool, which was clinched after polymeric re-solidification. The experimental results prove the ability to join metals and polymers while creating an integral channel in a single process step using HFSC. Despite the positive effect of irregular shaped channels on heat exchange, the numerical models evidenced a detrimental effect of 14.3 and 16.3% on ultimate tensile and flexural loads, respectively. This way, this fabrication technology evidenced promising characteristics that are suitable for manufacturing thermal management systems such as conformal cooling for plastic injection molding or battery trays for EVs. Full article

As research on new, lightweight energy vehicles continues to develop, the application of high-strength steel sheets with tensile strength greater than 1 GPa and their mechanical clinching technology, which is associated with aluminum alloys, has emerged as a new research focus. However, due to the challenges associated with the cold deformation of high-strength steel, conventional mechanical clinching processes often fail to establish effective joint interlocking, resulting in weak connections. This study proposes a center-punching mechanical clinching process for connecting DP980 high-strength steel to AL5052 aluminum alloy. The mechanical evolution during the forming process was analyzed via finite element simulation. An orthogonal experimental design was employed to optimize key geometric parameters of the punch and die, yielding the optimal configuration for the mold. Mechanical testing of the joint demonstrated average pull-out force and pull-shear forces of 1124 N and 2179 N, respectively, confirming the proposed process’s ability to successfully connect high-strength steel and aluminum alloy. Full article

Initially, the effects of sheet combinations for joining two sheets, including 780 MPa steel and A5052 aluminum alloy sheets, on the joined cross-sectional shapes of the sheets in a clinch-bonding process and the tension-shear load of joined sheets were investigated. The effect of an adhesive on the amounts of the interlock and the minimum thickness in the upper sheet was not large, whereas the effect of the sheet combination was observed. Subsequently, for joining the upper 980 MPa ultra-high-strength steel and lower aluminum alloy sheets in the clinch-bonding process, the effects of the die shape, punch velocity, and sheet holding force on the joinability were investigated. As a result, defect-free conditions were narrowly constrained. Finally, a method that involved controlling material flow using an adhesive with fine particles to increase friction between the sheets was introduced. The upper 980 MPa steel and lower aluminum alloy sheets were successfully joined using this approach. Full article

In recent years, with the rapid advancement of automotive lightweight technology, the mechanical clinching process between aluminum alloy and ultra-high-strength steel sheets has received extensive attention. However, the low ductility of ultra-high-strength steel sheets often results in conventional mechanical clinching processes producing joints that either fail to establish effective interlocks or cause the steel sheets to fracture. To address this issue, a novel mechanical clinching process is presented, called center-punching mechanical clinching (CPMC). This innovative process employs a method of punching, flanging, and bulging gradation to achieve the mechanical clinching of aluminum alloy and ultra-high-strength steel sheets in a single step. In order to determine the effects of different parameters on the quality and strength of the joint, an experimental study was carried out for various die depths and diameters based on the condition of constant punch size. Based on tensile and shear tests, the static strength and failure modes of CPMC joints were analyzed. The results indicated that the CPMC process significantly enhances the connectivity of joints for AA5052 aluminum alloy and DP980 ultra-high-strength steel. Optimal tensile and shear strengths of 1264 and 2249 N, respectively, were achieved at a die depth of 2.2 mm and a diameter of 10.4 mm. The CPMC process provides new ideas for the mechanical clinching of aluminum alloy and ultra-high-strength steels. Full article

With the rapid development of lightweight automobiles, the clinching joint technology of ultra-high-strength steel with aluminum alloy sheets have been paid more and more attention. However, due to significant differences in plastic deformation capabilities between the two metals, particularly the difficulty of steel sheet deformation, conventional clinching processes often result in insufficient joint interlocking or fracture issues. Although the preliminary use of clinching processes with preforming methods has shown some effectiveness in connecting two types of sheets, the bond strength is not high. This study employs finite element simulation and orthogonal optimization methods to investigate the impact of relevant process parameters on joint morphology in clinching processes with preforming. Under the condition of optimizing process parameters, a clinching punch with an added pressure-step structure was proposed to compact the joint and further enhance joint quality. Experimental verification demonstrates the feasibility of the improved clinching processes with preforming for bonding ultra-high-strength steel and aluminum alloy sheets. Full article

The extensive use of carbon fiber-reinforced composites and aluminum alloys represents the highest level of automotive body-in-white lightweighting. The effective and secure joining of these heterogeneous materials remains a prominent and actively researched topic within the scientific community. Among various joining techniques, clinching has emerged as a particularly cost-effective solution, experiencing significant advancements. However, the application of clinching is severely limited by the properties of the joining materials. In this work, various clinching processes for the joining of composites and aluminum alloys reported in recent research are described in detail according to three broad categories based on the principle of technological improvement. By scrutinizing current clinching technologies, a forward-looking perspective is presented for the future evolution of clinching technology in terms of composite–aluminum joints, encompassing aspects of tool design, process analysis, and the enhancement of joint quality. This work provides an overview of current research on clinching of CFRP and aluminum and serves as a reference for the further development of clinching processes. Full article

This paper presents the deformation of a joined sheet after the clinch riveting process. The DX51D steel sheet with zinc coating was used. The samples to be joined with clinch riveting technology had a thickness of 1 ± 0.05 mm and 1.5 ± 0.1 mm. The sheet deformation was measured before and after the joining process. The rivet was pressed in the sheets with the same dimension between the rivet axis and three sheet edges: 20, 30, and 40 mm. For fixed segments of the die, from the rivet side close to the rivet, the sheet deformation was greater than that of the area with movable segments. The movement of the die’s sliding element caused more sheet material to flow in the space between the fixed part of the die and movable segments. Hence, the sheet deformation in these places was smaller than for the die’s fixed element—the sheet material was less compressed. For sheet thickness values of 1.5 mm and a width value of 20 mm, the bulk of the sheet was observed. For a sheet width of 20 mm, it was observed that the deformation of the upper and lower sheets in the area of the rivet was greater than for sheet width values of 30 or 40 mm. Full article

Clinch Dace (Chrosomus sp. cf. saylori) is a newly recognized and yet-undescribed species of minnow with a restricted and fragmented distribution in the upper Tennessee River basin in southwestern Virginia, USA. We collected Clinch Dace from seven streams and observed variations at nine selectively neutral microsatellite DNA loci to infer population genetic processes and identify units for conservation management. Bayesian cluster analysis showed that three of the seven surveyed populations were genetically distinct, while the other four populations showed signs of recent admixture. Estimated effective population sizes and m-ratios were low within most populations, suggesting loss of alleles due to recent genetic drift. Positive F_IS values, high average individual inbreeding coefficients, and high degrees of inferred relatedness among individuals suggested that inbreeding is taking place in some populations. F_ST values were high, and analysis of molecular variance indicated genetic divergence among populations. These indicators suggest that Clinch Dace populations are subject to the genetic processes that are characteristic of small and isolated populations. Full article

Clinching is a manufacturing method of mechanically joining two or more materials without the use of heat or additional components. This process relies on high plastic deformation to create a secure bond. Clinching technology is widely used for joining materials of various grades and thicknesses. Especially in the automotive industry, clinching is an alternative to resistance spot welding. However, the load-bearing capacity of clinched joints is comparatively lower when compared to resistance spot-welded joints. This research aimed to increase the load-carrying capacity of clinched joints. To enhance the load-bearing capacity of the clinched joints, localized modification of the microstructure was carried out, primarily focusing on the neck area of the joint. The alteration of the microstructure within the clinched joint was accomplished through the application of localized heating using the resistance spot welding method. The microstructure distribution in the clinched joint region was analyzed using light and scanning electron microscopy, as well as microhardness measurements. Two material grades, micro-alloyed steel HX420LAD+Z and dual-phase ferritic–martensitic steel HCT600X+Z, were tested. Each grade underwent five groups of ten samples, which were subjected to identical experimental conditions of local heating by resistance spot welding (RSW) and clinching. The utilization of RSW on the clinched joint region resulted in an average enhancement of 17% in the load-carrying capacity for material HCT600X+Z, and an average increase of 25% for material HX420LAD+Z. Full article

Metal–organic frameworks (MOF) are a class of porous materials with various functions based on their host-guest chemistry. Their selectivity, diffusion kinetics, and catalytic activity are influenced by their design and synthetic procedure. The synthesis of different MOFs has been of considerable interest during the past decade thanks to their various applications in the arena of sensors, catalysts, adsorption, and electronic devices. Among the different techniques for the synthesis of MOFs, such as the solvothermal, sonochemical, ionothermal, and mechanochemical processes, microwave-assisted synthesis has clinched a significant place in MOF synthesis. The main assets of microwave-assisted synthesis are the short reaction time, the fast rate of nucleation, and the modified properties of MOFs. The review encompasses the development of the microwave-assisted synthesis of MOFs, their properties, and their applications in various fields. Full article

Given strict emission targets and legal requirements, especially in the automotive industry, environmentally friendly and simultaneously versatile applicable production technologies are gaining importance. In this regard, the use of mechanical joining processes, such as clinching, enable assembly sheet metals to achieve strength properties similar to those of established thermal joining technologies. However, to guarantee a high reliability of the generated joint connection, the selection of a best-fitting joining technology as well as the meaningful description of individual joint properties is essential. In the context of clinching, few contributions have to date investigated the metamodel-based estimation and optimization of joint characteristics, such as neck or interlock thickness, by applying machine learning and genetic algorithms. Therefore, several regression models have been trained on varying databases and amounts of input parameters. However, if product engineers can only provide limited data for a new joining task, such as incomplete information on applied joining tool dimensions, previously trained metamodels often reach their limits. This often results in a significant loss of prediction quality and leads to increasing uncertainties and inaccuracies within the metamodel-based design of a clinch joint connection. Motivated by this, the presented contribution investigates different machine learning algorithms regarding their ability to achieve a satisfying estimation accuracy on limited input data applying a statistically based feature selection method. Through this, it is possible to identify which regression models are suitable to predict clinch joint characteristics considering only a minimum set of required input features. Thus, in addition to the opportunity to decrease the training effort as well as the model complexity, the subsequent formulation of design equations can pave the way to a more versatile application and reuse of pretrained metamodels on varying tool configurations for a given clinch joining task. Full article

The paper presents research regarding a thermally supported multi-material clinching process (hotclinching) for metal and thermoplastic composite (TPC) sheets: an experimental approach to investigate the flow pressing phenomena during joining. Therefore, an experimental setup is developed to compress the TPC-specimens in out-of-plane direction with different initial TPC thicknesses and varying temperature levels. The deformed specimens are analyzed with computed tomography to investigate the resultant inner material structure at different compaction levels. The results are compared in terms of force-compaction-curves and occurring phenomena during compaction. The change of the material structure is characterized by sliding phenomena and crack initiation and growth. Full article

An implicit, elastoplastic, finite element method (FEM) with multi-body treatment function was applied to accurately analyze the real-world shaft clinching of a duplex-pair tapered roller (DPTR) wheel-bearing unit (WBU) under minimal assumptions during modeling. The inner races were viewed as elastoplastically deformable and were fitted to the hub shaft before clinching by imposing a thermal load reflecting the mechanical load of press-fitting. The forming roller (i.e., the power source) was considered to be force-prescribed, similar to the approach on real shop floors. The predictions focused on the homogenizing stage, during which the two inner races bear the preload. At this time, local plastic deformation occurred at the end of the hub shaft and in the armpit area and the cavity was either maintained or enlarged. The predicted cavity size in case of force-prescribed forming roller increased, compared with the velocity-prescribed forming roller. The residual stress became axisymmetric and was divided into two parts by the cavity. These findings allow engineers to control the pre-stresses imparted to the inner races of tapered roller bearing assemblies. Full article

As a joining-by-forming process, clinching and the use of functional elements enable low-energy joining of components through form, force, and, under certain conditions, material closure. In addition to the transmission of mechanical forces, these joining processes can be qualified for additional electrical contact within the scope of functional integration for electro-mobile applications. For this purpose, maximizing the force and material closure is necessary to ensure a long-term, stable transmission of electrical currents. To this end, the electrical properties of the joints were optimized. The investigations carried out show the long-term behavior under normal operating conditions and the short-circuit case. Full article

Rotated clinching is a novel cold plastic deformation joining process, which is suitable for the multi-point simultaneous joining of sheet metals. However, the effect of various parameters on the mechanical properties of joints using rotated clinching remains unclear. The purpose of this study is to analyse the important parameters that affect the joint’s shearing strength and relationship between them. The relational expression between the four process parameters (die depth, rotation angle, small fillet radius and large fillet radius) and joint shearing strength was established using the response surface method. Additionally, the quantitative relationship between them was expressed by this relational expression, and the significance of process parameters were evaluated using the analysis of variance. The results revealed that the most significant parameter regarding the shearing strength was die depth h, with the contribution of 47.1%, followed by rotation angle α and small fillet radius r₁, with the contributions of 26.8% and 8.2%, respectively, whereas the large fillet radius R₁ is the least significant, there is a significant interaction effect between R₁ and α, with the contribution of 5.4%. The shearing strength had a negative relationship with the die depth h and small fillet r₁, whereas it had a positive relationship with rotation angle α. The predicted maximum value of the shearing strength was 1231.92 N at h = 2.29 mm, r₁ = 0.46 mm, R₁ = 1.27 mm and α = 18.45° in the range of given design parameter values. The experimental values of the shearing strength comprised approximately 74% of the predicted values. Full article