Dissimilar Material Joints Research Articles

Evaluation of the interfacial strength for adhesive joint of dissimilar materials by wedge testing method

Evaluation of the interfacial strength for adhesive joint of dissimilar materials by wedge testing method

摩擦重ね接合によるステンレス鋼と炭素繊維強化熱可塑性樹脂との異材接合

The effect of joining speed on the joining strength of the dissimilar materials joint of the SUS304/ carbon fiber reinforced thermoplastic (CFRTP) was investigated. SUS304 plates (150mm×75mm×2.0mm) and CFRTP (consisted of PA6 matrix and 20wt% carbon fiber) plates (150mm×75mm×3.0mm) were joined by friction lap joining (FLJ) using rotational WC-Co tool. Different joining speeds in the range from 1.67mm/s - 16.7mm/s and the tool rotation speed of 8.33 s-1 were selected as processing conditions. Direct joining of SUS304/CFRTP was accomplished at all of joining speeds by FLJ. The tensile shear strength of the joint increased with increasing joining speed up to 3.33mm/s, however, it decreased from the joining speed of 3.33mm/s to 16.7mm/s. The interfacial fracture occurred at all of joining speeds. The fractured surface analysis of SUS304 revealed that teared fragments from the CFRTP base plate were bonded to SUS304. At the lower joining speed, the excessive heat input caused thermal decomposition of PA6 from the matrix of CFRTP resulted bubbles; the joint strength was decreased because of these bubbles. The shortage of the heat input at the higher joining speed caused insufficient wetting of molten PA6 to SUS304, which resulted in the decreased strength of the joint.

Nonlinear Optimization Methods for the Determination of Heat Source Model Parameters

In this paper the technique of parameter identification is investigated to reconstruct the 3D transient temperature field for the simulation of laser beam welding. The reconstruction bases on volume heat source models and makes use of experimental data. The parameter identification leads to an inverse heat conduction problem which cannot be solved exactly but in terms of an optimal alignment of the simulation and experimental data. To solve the inverse problem, methods of nonlinear optimization are applied to minimize a problem dependent objective function.In particular the objective function is generated based on the Response Surface Model (RSM) technique. Sampling points on the RSM are determined by means of Finite-Element-Analysis (FEA). The scope of this research paper is the evaluation and comparison of gradient based and stochastic optimization algorithms. The proposed parameter identification makes it possible to determine the heat source model parameters in an automated way. The methodology is applied on welds of dissimilar material joints.

Creep Fatigue Life Assessment of a Pipe Intersection with Dissimilar Material Joint by Linear Matching Method

As the energy demand increases the power industry has to enhance both efficiency and environmental sustainability of power plants by increasing the operating temperature. The accurate creep fatigue life assessment is important for the safe operation and design of current and future power plant stations. This paper proposes a practical creep fatigue life assessment case of study by the Linear Matching Method (LMM) framework. The LMM for extended Direct Steady Cycle Analysis (eDSCA) has been adopted to calculate the creep fatigue responses due to the cyclic loading under high temperature conditions. A pipe intersection with dissimilar material joint, subjected to high cycling temperature and constant pressure steam, is used as an example. The closed end condition is considered at both ends of main and branch pipes. The impact of the material mismatch, transitional thermal load, and creep dwell on the failure mechanism and location within the intersection is investigated. All the results demonstrate the capability of the method, and how a direct method is able to support engineers in the assessment and design of high temperature component in a complex loading scenario.

Performance Prediction for Ultrasonically Welded Dissimilar Materials Joints

Ultrasonic metal welding has been used to join multiple layers of battery tabs with the bus bar in lithium-ion battery assembly operations. This paper describes joint performance models for ultrasonic metal welds of multiple layers of dissimilar battery tab materials, i.e., aluminum and copper. Finite element (FE) models are developed to predict the mechanical performance of the ultrasonically welded joints. The models predict peak shear load, energy absorption capability, and failure modes, which are necessary for modeling product performance and defining process requirements for the welds. The models can be adjusted to represent different quality of welds created in conditions of underweld (UW), normal-weld (NW), or overweld (OW) using physical attributes observed through microscopic analysis. The models are validated through lap shear tests, which demonstrate excellent agreement for the maximum force in the NW condition and good agreement for the UW and OW conditions. The models provide in-depth understanding of the relationship among welding process parameters, physical weld attributes, and the weld performance. The models also provide significant insight for further development of ultrasonic welding process for battery tabs and help optimize welding process for more than four-layered joints.

Analysis of singular stresses at a vertex and along a singular line in three-dimensional bonded joints using a conservative integral

Abstract In the present study, singular stress fields in three-dimensional dissimilar material joints are investigated at a vertex and along a free edge (a singular line) of an interface. A conservative integral based on Betti's reciprocal principle is used to calculate the intensities of the singularities in three-dimensional dissimilar material joints. Two geometries in which the angle between the side surface of the vertex equals 60° and 90° and a range of material combinations are used to investigate the characteristics of the stress singularity. The relationships between the angular functions of the stresses at the vertex and along the singular line are studied. The intensities of the singularities at several positions along the singular line of the interface are determined. Then, the relationship between the intensity of the singularity at the vertex and that at a point located on the singular line is investigated. Finally, the intensities of the singularities along the singular line can be described as a function of the distance from the vertex and the singular stress at the vertex.

Study on the microstructure, mechanical properties and corrosion behaviour of S355JR/316L dissimilar welded joint prepared by gas tungsten arc welding multi-pass welding process

In this study, the joints of dissimilar materials between S355JR carbon steel and 316L stainless steel were welded by gas tungsten arc welding (GTAW) multi-pass welding process. Characterisations of microstructure, mechanical properties and corrosion behaviours of dissimilar joint were investigated. The experimental results reveal that the microstructure of weld metal (WM) is austenite and vermiform δ-ferrite, and they cross-distribute in the weld seam. Moreover, there is a decarburisation layer on the interface of S355JR/WM, but the detrimental phase σ and M23C6 (chromium carbide) are not observed in the WM through X-ray diffraction. The fracture of the S355JR/316L welded joints always occurs in the S355JR heat affected zone during tensile test. Mechanical properties of the welded joints prepared by GTAW can meet the requirements of engineering application. The electrochemical corrosion test is also indicates that the corrosion resistance of WM decreases compared with the 316L base material. The corrosion products of S355JR/316L dissimilar welded joints in 3.5 wt-% NaCl aqueous solution mainly are α-Fe and FeOOH.

Methods to Predict Stresses in Cutting Inserts Brazed Using Iron-Carbon Brazing Alloy

This work describes a method for predicting residual and operating stresses in a flat-form tool insert made of tungsten free carbides brazed using iron-carbon alloy. According to the studies’ results it is concluded that the recommendations relating to the limitation of a melting point of tool brazing alloys (950-1100°C according to different data) are connected with a negative impact on tools as a composite made of dissimilar materials rather than on hard alloys as a tool material. Due to the cooling process stresses inevitably occur in the brazed joint of dissimilar materials, and these stresses increase with the higher solidification temperature of the brazing alloy.

Peculiarities of the structural-phase state of a brazing zone of dissimilar metal joints

The present work is devoted to the study of the structural-phase state of the brazed joints of dissimilar materials obtained by rapidly quenched filler metals before and after tests in the working conditions. The constructive elements of the International Thermonuclear Experimental Reactor (ITER) working chamber were selected: mock-ups of the first wall (a beryllium cladding joined with the heat-removing bronze by high-temperature brazing) and the divertor (a tungsten cladding with built-up copper, brazing of copper with bronze). An analysis of the investigated samples and the data on the structural-phase state of the brazed joints and its evolution as a result of a cyclic thermal impact was carried out by metallography and electron microscopy.

Characterisation of Al–Ti dissimilar material joints fabricated using ultrasonic additive manufacturing

Ultrasonic additive manufacturing (UAM) is a solid state manufacturing process for joining thin metal tapes using principles of ultrasonic metal welding. The process operates at low temperatures, enabling dissimilar material welds without generating harmful intermetallic compounds. In this study, a 9 kW UAM system was used to create joints of Al 1100 and commercially pure titanium. Viable process parameters were identified through pilot weld studies via controlled variation of weld force, amplitude and weld speed. Push-pin delamination tests and shear tests were performed, comparing as-built, heat treated and spark plasma sintering treated samples. Heat treated and spark plasma sintering treated samples yielded mechanical strengths over twice that of as-built samples. Electron backscatter diffraction measurements show that deformation and grain refinement only take place in the aluminium layers. Heat treated samples exhibit a thin intermetallic layer, which is hypothesised as constraining the interface, leading to the improved strength.

Curing-Induced Debonding and Its Influence on Strength of Adhesively Bonded Joints of Dissimilar Materials

Adhesive bonding is thought to be a suitable method for joining dissimilar materials, such as aluminum to steel in multimaterial car-body manufacturing, but when it is combined with other joining methods, such as spot welding or self-piercing riveting, curing the adhesive at elevated temperature induces problems, such as distortion and adhesive debond. In this study, the effects of debonds were investigated by examining load–displacement curve and dissipated energy in lap-shear and peeling tests of artificially debonded joints. The results showed that the debonds caused by curing are of dog-bone type or stripe failure type, and both of them have little influence on the peel strength, but have strong influence on the shear strength and energy absorption. For the lap-shear specimens, the debonds reduce the bonding area, leading to the reduction in maximum shear force. For the double cantilever beam specimens, the debonds produce little influence on maximum peeling force but obvious variations in the peeling load curve. The energy absorption values are inversely proportional to the debonds due to the reduction in bonding area. The overall results from this research facilitate the understanding of the debonding mechanism caused by curing-induced distortion by revealing two types of debond patterns in dissimilar material bonding joints and their influences on joint performance.

表面処理を施したA5052と樹脂の異材接合体の界面強度評価

表面処理を施したA5052と樹脂の異材接合体の界面強度評価

分子動力学法による異材接合法の三次元特異応力場解析

分子動力学法による異材接合法の三次元特異応力場解析

Galvanic corrosion of aircraft bonded joints as a result of adhesive microcracks

This paper studies the root causes of a corrosion failure found in the Airbus A320 CFM56-5b intakes. This failure occurs in a dissimilar materials joint and is strongly related to the adhesive loss of integrity at very low temperatures. The ductility reduction of the adhesive at low temperatures promotes the microcracks formation within the adhesive layer of the bonded joint, which in turn sparks the corrosion process. These microcracks allow the infiltration of dust, moisture, contaminants and salt water in the interface between the adhesive and adherents, which promotes the creation of a dielectric between the joint adherents and consequently their galvanic corrosion. Results show that the thermal strains of the dissimilar joint materials at very low temperatures significantly reduces the adhesive load margin reserved for drag loads. Some remarks are drawn in order to improve the joint corrosion resistance.

3次元異方性—等方性接合体の界面端近傍における特異応力場解析

Recently, dissimilar material joints are used in industrial products for improving functionality and strength. In this study, the joining strength of adhesive joints of carbon fiber composite material which is an anisotropic materials are investigated through a conservative integral. The order of singularity and the angular function are calculated using the eigenvalue analysis based on finite element method. Intensity of stress singularity is calculated using a conservative integral. By using these analysis methods, quantitative evaluation of stress singular field at the edge of interface in the adhesive joints of carbon fiber reinforced plastic is conducted.

３次元異材接合体の界面端近傍における特異応力場解析

３次元異材接合体の界面端近傍における特異応力場解析

Microstructure and Porosity of Laser-welded Dissimilar Material Joints of HR-2 and J75

Dissimilar laser welding of HR-2 and J75 has a wide range of applications in high-and low-temperature hydrogen storage. The porosity distributions of the welded joints were investigated at different line energies, penetration status, and welding positions (1G, 2G, and 3G). The effect of the welding position on the welding appearance was evident only at high line energies because of the essential effect of gravity of the larger and longer dwelling molten pool. The porosity of the welded joints between the solutionised and aged J75 and HR-2 at the 3G position and partial penetration was located at the weld centre line, while the porosity at the 2G position with full penetration was distributed at the weld edges, which is consistent with the distribution of floating slag. Full keyhole penetration resulted in minimum porosity, partial penetration resulted in moderate porosity, and periodic molten pool penetration resulted in maximum porosity.

A1100／亜鉛めっき鋼板異材摩擦攪拌接合体の破壊プロセスおよび強度特性に対する影響因子

A1100／亜鉛めっき鋼板異材摩擦攪拌接合体の破壊プロセスおよび強度特性に対する影響因子

1107 表面処理を施したアルミニウム合金と樹脂の異材接合体の強度特性(OS8-2 材料力学と計算力学の新展開)

1107 表面処理を施したアルミニウム合金と樹脂の異材接合体の強度特性(OS8-2 材料力学と計算力学の新展開)

破壊モードの遷移を利用した樹脂/金属異材接合体の界面強度評価法の提案

Strength of dissimilar materials joint between resin and surface treated metal was studied. In the present study, A5052 aluminum alloy was used as a metallic material, and polyamide 66, polycarbonate and polypropylene were used as resin materials. The dissimilar materials direct joints were produced by insert molding technique. Tensile test was carried out to evaluate the strength of the joints and observation of cross section in A5052 after the tensile test was conducted to investigate relationship between fracture mode and depth of groove introduced at surface of A5052. The joint of PA66 showed the highest strength, then the joint of PC showed the second highest strength and the joint of PP had the lowest strength. According to the observation of cross section, pull out and base material failure were observed as fracture modes of the joints. Moreover, the fracture mode changed from pull out mode to base material failure mode by increasing of the grove depth. Transition depth of the groove was defined by using transition of the fracture modes from pull out to base material failure. Finite element stress analysis was carried out to evaluate interfacial strength by using a model taking into account transition depth of the groove and strength of base material of the resins. Result of the analysis showed that the joint of PA66 had the highest strength, then the joint of PC showed the second highest strength and the joint of PP had the lowest strength.