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1
Zare, Samira, Alex Spaeth, Sandya Suresh e Mircea Teodorescu. "Three-Dimensionally Printed Self-Lock Origami: Design, Fabrication, and Simulation to Improve Performance of Rotational Joint". Micromachines 14, n. 8 (21 agosto 2023): 1649. http://dx.doi.org/10.3390/mi14081649.
Testo completoAbstract (sommario):
Origami structures have made significant contributions to the field of robotics, offering various advantages. One such advantage is their ability to conserve space by transforming the structure into a compact form. Additionally, many origami structures can be fabricated in a flat state to simplify manufacturing, giving them the potential for large-scale and cost-effective production. Rotational joints play a crucial role in the construction of robotic systems, yet origami rotational joints can suffer from a limited range of motion. We previously theoretically proposed the Self-Lock Joint to address this issue, but it is only partially flat-foldable. This paper presents a novel approach to the 3D printing of modular origami joints, such as the Self-Lock Joint, using 3D-printed plates joined with a fabric layer. The compliance of the fabric can improve the joint’s semi flat-foldability or even enable it to achieve complete flat-foldability. Furthermore, the rotational motion of the joint is enhanced, allowing for close to 360 degrees of rotational movement. We assess the physical properties of the joint under both loaded and unloaded conditions in order to identify design trade-offs in the physical properties of the joints. Moreover, as a proof of concept, we construct and demonstrate manipulators utilizing these joints. The increase in rotational movement enabled by this fabrication method, coupled with the compliant joint’s flat-foldability and modular nature, make it a promising candidate for use in a wide range of applications.
2
Lyu, Naesung, e Kazuhiro Saitou. "Decomposition-Based Assembly Synthesis of Space Frame Structures Using Joint Library". Journal of Mechanical Design 128, n. 1 (25 novembre 2004): 57–65. http://dx.doi.org/10.1115/1.1909203.
Testo completoAbstract (sommario):
This paper presents a method for identifying the optimal designs of components and joints in the space frame body structures of passenger vehicles considering structural characteristics, manufacturability, and assembleability. Dissimilar to our previous work based on graph decomposition, the problem is posed as a simultaneous determination of the locations and types of joints in a structure and the cross sections of the joined structural frames, selected from a predefined joint library. The joint library is a set of joint designs containing the geometry of the feasible joints at each potential joint location and the cross sections of the joined frames, associated with their structural characteristics as equivalent torsional springs obtained from the finite element analyses of the detailed joint geometry. Structural characteristics of the entire structure are evaluated by finite element analyses of a beam-spring model constructed from the selected joints and joined frames. Manufacturability and assembleability are evaluated as the manufacturing and assembly costs estimated from the geometry of the components and joints, respectively. The optimization problem is solved by a multiobjective genetic algorithm using a direct crossover. A case study on an aluminum space frame of a midsize passenger vehicle is discussed.
3
kinaine, Alaa Faisal, e Haider M. Al-Jelawy. "Using Short Ultra-High Performance Concrete Link Slab as an Alternative to Steel Dowel Bars in Rigid Pavements". IOP Conference Series: Earth and Environmental Science 1232, n. 1 (1 settembre 2023): 012053. http://dx.doi.org/10.1088/1755-1315/1232/1/012053.
Testo completoAbstract (sommario):
Abstract To prevent problems from occurring at the joint region in bridge construction, link slab was introduced to hide the apparent expansion joint and retain its function. This research describes experimental tests that investigate the use of an ultra-high performance concrete (UHPC), for its high sustainability properties, as a short link slab instead of apparent expansion joints and their respective steel dowels in joint plain concrete pavement (JPCP) while maintaining the expansion joint’s proper function. Similar to dowelled joints, the proposed joint distributes load between adjoining slabs while allowing for contraction and expansion of the pavement due to temperature and moisture variations. Modified cantilever tests were conducted on JPCP slab segments with regular dowelled joints and UHPC link slab joints to investigate the load-deflection response and load transfer of both joints and make comparison. The experimental results showed that UHPC link slab specimens exhibited less deflection at the face of the joint and less relative deflection between the adjoining slabs than steel dowel bar specimens. The test outcomes also showed that joint width did not have a noticeable influence on the load-deflection behavior of the UHPC link slab specimens, but it obviously affected the dowelled joints. Also, UHPC link slab specimens showed an improvement in ultimate load capacity by 23.33% and 11% compared with dowelled joints. Furthermore, the UHPC link slab joints exhibited a better load transfer between slab segments than the dowelled joints. It was concluded that even a short link slab can be superior to standard dowelled joints
4
Vavrusova, Kristyna, Antonin Lokaj, David Mikolasek e Oldrich Sucharda. "Analysis of Longitudinal Timber Beam Joints Loaded with Simple Bending". Sustainability 12, n. 21 (9 novembre 2020): 9288. http://dx.doi.org/10.3390/su12219288.
Testo completoAbstract (sommario):
The joints in timber structures are often the decisive factor in determining the load-bearing capacity, rigidity, sustainability, and durability of timber structures. Compared with the fasteners used for steel and concrete structures, fasteners for timber structures generally have a lower load-bearing capacity and rigidity, with the exception of glued joints. Glued joints in timber structures constitute a diverse group of rigid joints which are distinguished by sudden failure when the joint’s load-bearing capacity is reached. In this contribution, the load-bearing capacity of a longitudinal joint for a beam under simple flexural stress is analyzed using glued, double-sided splices. Joints with double-sided splices and connecting screws were also tested to compare the load-bearing capacity and rigidity. A third series of tests was carried out on joints made using glued double-sided splices augmented with screws. The aim of this combined joint was to ensure greater ductility after the load-bearing capacity of the glued splice joint had been reached.
5
Kurtenoks, Viktors, Aleksis Kurajevs, Karina Buka-Vaivade, Dmitrijs Serdjuks, Vjaceslavs Lapkovskis, Viktors Mironovs, Andrejs Podkoritovs e Martins Vilnitis. "The Quality Assessment of Timber Structural Joints Using the Coaxial Correlation Method". Buildings 13, n. 8 (28 luglio 2023): 1929. http://dx.doi.org/10.3390/buildings13081929.
Testo completoAbstract (sommario):
With the growing popularity of timber structures, the requirement for reliable and non-destructive methods to assess the quality and condition of structural joints becomes increasingly essential. A novel coaxial correlations method is investigated to assess the degradation of panel-to-panel moment joints in timber structures. The method involves analysing the response data obtained from accelerometers placed on both sides of the joint and comparing the readings to evaluate the joint’s condition. A specific joint solution to simulate the degradation of the moment joint in laboratory conditions is selected based on its simplicity and the ease with which its degradation can be simulated. The joint consists of angle brackets joined with timber screws and bolts to plywood panels. Gradually unscrewing the timber screws reduces the joint’s stiffness to simulate wear and tear over time. The experimental setup includes static loading and finite element modelling (FEM) to determine the rotational stiffness of the investigated joint at each degradation level. A dynamic experiment using vibration loading with sweep signal in the frequency range of 10 Hz to 2000 Hz is conducted to assess the quality of the joint. The conducted research provides valuable insights into the behaviour of timber panel-to-panel connections. The findings highlight the relationship between joint stiffness, vertical displacements, and the proposed dimensionless parameter, volume root mean square value (RMSvol), which offers a more comprehensive assessment of the joint’s condition in three spatial directions. As a result of the research, it has been established that, in the case of linear-type connections, unlike point-type joints, there is a possibility of signal scattering, so it is recommended that power comparisons and evaluations of the response signals from both accelerometers at the initial stage of applying the coaxial correlations method are performed.
6
Mucha, Jacek, e Waldemar Witkowski. "The Structure of the Strength of Riveted Joints Determined in the Lap Joint Tensile Shear Test". Acta Mechanica et Automatica 9, n. 1 (1 marzo 2015): 44–49. http://dx.doi.org/10.1515/ama-2015-0009.
Testo completoAbstract (sommario):
Abstract The article presents the analysis of the structure of the load capacity of riveted joints. For the four joining systems the lap joint specimens were made and tested in the shearing test. The joints were prepared for the three combinations of the DC01 steel and EN AW- 5754 aluminium alloy sheets with the thickness of 2mm. On the basis of the obtained load-elongation diagram tensile shear test curves, the basic parameters defined in the ISO/DIS 12996 standard were determined. In the case of the conventional riveted joints the maximum load capacity of the joint is determined by the strength of the fastener. For the joints with aluminium-steel blind rivet , the load capacity of the joint was on the strength limit of the rivet tubular part and on the strength limit of the sheet material. The strength of the SSPR joint is determined by the mechanical properties of the material of the joined sheets. From all sheets and rivet specimens arrangements the highest load capacity of the joint was obtained for the DC01 sheet material joints, and the lowest load capacity of the joint was obtained for the EN AW-5754 sheet material joints.
7
Harl, Boštjan. "Probabilistic behaviour of joints on joint forces in mechanisms". Tehnicki vjesnik - Technical Gazette 22, n. 1 (2015): 113–17. http://dx.doi.org/10.17559/tv-20131023220214.
Testo completo
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Hua, Qiang, Weigang Zhou, Shiqiang Zhu, Yunchang Yao, Chao Cheng, Anhuan Xie e Dan Zhang. "Design of a High-torque Robot Joint and Its Control System". Journal of Physics: Conference Series 2281, n. 1 (1 giugno 2022): 012007. http://dx.doi.org/10.1088/1742-6596/2281/1/012007.
Testo completoAbstract (sommario):
Abstract The robot joint is one of the key components of robots. With the wide application of robot joints, the demand for joint torque is becoming higher and higher. However, at present, most high-torque robot joints are generally large in weight and size, which creates problems for some applications. For this purpose, a high-torque and high-torque-density robot joint is proposed. To improve the joints’ torque density, the lightweight motor and reducer with a large reduction ratio are selected, and the mechanical structure design is based on weight reduction, miniaturization, and heat dissipation. The maximum torque of the proposed robot joint can reach up to 182Nm, and its mass is only 1.8kg. Besides, an embedded control system is designed to control the robot joint. Many experiments were conducted to measure the robot joint’s characteristics, such as torque, speed, and control features. And the designed robot joints are successfully applied to a biped robot. The results verify the performance of the designed robot joint and its control system.
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Akram, Shazad, Johan Sidén e Kent Bertilsson. "Battery Powered Inductive Welding System for Electrofusion Joints in Optical Fiber Microducts". Electronics 10, n. 6 (21 marzo 2021): 743. http://dx.doi.org/10.3390/electronics10060743.
Testo completoAbstract (sommario):
Optical fiber microducts are joined together by mechanical joints. These mechanical joints are bulky, require more space per joint, and are prone to air pressure leakage and water seepage during service. A battery powered electrofusion welding system with a resistive-type joint has been recently developed to replace mechanical joints. These resistive-type electrofusion joints require physical connectors for power input. Due to a different installation environment, the power input connectors of resistive optical fiber microduct joints may corrode over time. This corrosion of connectors will eventually cause water seepage or air pressure leakage in the long run. Moreover, due to connector corrosion, resistive-type optical fiber microduct joints cannot be re-heated in future if the need arises. In this study, an inductively coupled electrofusion-type joint was proposed and investigated. This inductive-type electrofusion joint is not prone to long-term corrosion risk, due to the absence of power connectors. Inductive-type electrofusion joints can be re-heated again for resealing or removal in the long run, as no metal part is exposed to the environment. The battery powered inductive welding system can be easily powered with a 38 volts 160 watt-hour battery. The inductive-type electrofusion joint was welded within one second, and passed a 300-newton pull strength test and a 10-bar air pressure leakage test. It was demonstrated that the power input requirement for inductive electrofusion joints is 64% higher than that of resistive electrofusion joints. However, these inductive joints are relatively easy to manufacture, inexpensive, have no air leakage, and no water seepage risk in highly corrosive environments.
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Yousefi, Armin, Ahmad Serjouei, Reza Hedayati e Mahdi Bodaghi. "Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys". Materials 14, n. 9 (23 aprile 2021): 2171. http://dx.doi.org/10.3390/ma14092171.
Testo completoAbstract (sommario):
In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.
11
Záborský, Vladimír, Gourav Kamboj, Adam Sikora e Vlastimil Borůvka. "Effects of selected factors on spruce dowel joint stiffness". BioResources 14, n. 1 (14 dicembre 2018): 1127–40. http://dx.doi.org/10.15376/biores.14.1.1127-1140.
Testo completoAbstract (sommario):
Joints are used to join furniture parts, and they represent a critical part of the structure of furniture. The quality of joints is greatly affected by the accuracy of their execution. When designing furniture, it is important to carefully consider the type of joint used so that it can hold all the joined elements together. Under loading of the joined structures, internal forces develop, which can lead to failure of the joints. This study investigated the elastic stiffness of spruce (Picea abies L.) dowel joints. The effects of selected factors such as the type of loading (compressive versus tensile), the size of the dowels (one-half versus one-third of the thickness of the joined elements), the type of adhesive used (polyvinyl acetate versus polyurethane), and annual ring deflection were examined. Spruce dowel joints exhibited the highest elastic stiffness values with a higher-diameter dowel glued with PUR adhesives and subjected to compressive loading. The impact of annual rings was not a significant factor. Finally, the reference type joints were compared with other commonly used types, such as three types of mortise and tenon joints (simple, haunched, and dovetail).
12
Gaikwad, Vaibhav, e Satish Chinchanikar. "Investigations on ultrasonic vibration-assisted friction stir welded AA7075 joints: Mechanical properties and fracture analysis". Metal Working and Material Science 26, n. 2 (7 giugno 2024): 6–22. http://dx.doi.org/10.17212/1994-6309-2024-26.2-6-22.
Testo completoAbstract (sommario):
Introduction. Joint efficiency and strength, particularly in aluminum alloys, are crucial in aerospace, defense, and industrial applications. Post-welding treatments like shot peening and laser shock peening significantly improve joint efficiency and strength, enhancing fatigue life, grain structure, and tensile strength. The purpose of the work. The literature reviewed shows that the ultrasonic vibration-assisted friction stir welding (UVaFSW) and post-weld treatment improved the mechanical properties and material flow. However, limited studies have been observed on the UVaFSW joints of AA7075-T651, considering the consequence of welding speed, tool rotation, and post-weld shot peeing treatment. The methods of investigation. The study investigates the ultrasonic vibration-assisted friction stir welded (UVaFSwed) AA7075-T651 joint's tensile strength, microhardness, microstructure, and fracture behavior, considering the impact of tool rotation, welding speed, and post-weld shot peening treatment. Results and Discussion. The post-weld treated shot-peened UVaFSWed joints demonstrated the maximum tensile strength of 373.43 MPa, the microhardness of 161 HV, and the lowest surface roughness of 15.16 µm at 40 mm/min welding speed when compared to the friction stir-welded (FSWed) joints. These results indicate that shot peening improved the mechanical properties and surface quality of the UVaFSWed joints. The high tensile strength and low surface roughness make these joints suitable for applications requiring strength and aesthetics. The fracture for the shot peened UVaFSWed joints mainly occurred in the heat-affected zone (HAZ) during the tensile test. It could be attributed to the higher temperature experienced during welding, which resulted in grain growth and decreased material strength in the HAZ. The shot-peened UVaFSWed joint has a more uniform grain distribution than the FSWed one, which contributed to the joint's higher tensile strength. The fractured surface of the shot peened UVaFSWed joints showed larger, equiaxed, and shallow dimples, resulting in higher ultimate tensile strength (UTS) and microhardness compared to the conventional FSWed joints. The mechanical properties and microstructure observed in the welding zones of shot peened UVaFSWed joints are superior to those of conventional FSW joints. However, further investigation is required to determine the specific factors contributing to this localized failure at HAZ, considering the effects of shot peening parameters. This study also suggests the potential for optimizing shot peened UVaFSWed joints of AA7075-T651.
13
Wang, Xiangyang, Xiantang Zhang, Jingshuang Zhang, Hongmin Zhou, Peng Zhang e Dan Li. "Study on the Influence of the Joint Angle between Blast Holes on Explosion Crack Propagation and Stress Variation". Processes 11, n. 9 (21 settembre 2023): 2805. http://dx.doi.org/10.3390/pr11092805.
Testo completoAbstract (sommario):
The joints and fissures in a natural rock mass can affect the mechanical properties of the rock mass, the propagation of a blasting stress wave, and the blasting effect of the smooth surface of roadways. In the process of roadway drilling and blasting, there will inevitably be some joints between the two blast holes. Taking the joint angle as the starting point, this paper studies the rule of rock explosion crack propagation and stress variation when there are joints with different angles between two blast holes and analyzes the influence of joints on rock mechanical properties and blasting effects. The numerical simulation method and the software ANSYS/LS-DYNA are used to establish 7 rock mass models with various joint angles. When there is no joint between two holes and joints of 15°, 30°, 45°, 60°, 75°, and 90°, the propagation of explosive cracks and stress variations in the rock mass are discussed. The results show that the joints at different angles have obvious guiding and blocking effects on the propagation of explosive cracks, and as joint angles increase, the guiding effect becomes more apparent and the blocking effect becomes weaker. The effective stress of the rock mass will vary depending on the angles of the joints between the hole and the joint. As the joint angle increases, the joint’s influence on the reflection and superposition of stress waves gradually weakens, and the peak value of the effective stress of the rock mass gradually decreases. The peak effective stress of the rock mass on the blasting side of the joint is similarly impacted by the superposition of stress waves, and the extreme value may be seen at the critical node of each change curve. The explosive crack will break through at the critical location because the maximal effective stress of the rock mass is distributed in a “W” form on the blasting side of the joint.
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Lee, M. M. K., T. Pine e T. B. Jones. "An experimental and finite element study of the torsional behaviour of T-joints in automotive structures". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, n. 2 (1 febbraio 2001): 231–40. http://dx.doi.org/10.1243/0954407011525601.
Testo completoAbstract (sommario):
Single box sections and T-joints (two box sections joined together at right angles) are commonly used to represent automotive components, such as pillars and sills, in laboratory testing. In the work presented herein, the torsional properties of T-joints were determined both experimentally and numerically. A factorial-design test programme comparing adhesive-bonded and spot-welded T-joints was carried out. Numerical models, generated using a general-purpose finite element program and validated against the test results, were used to investigate further the behaviour of the connection between the two box sections in a T-joint. The joining technique and the joint eccentricity at the connection (the distance of the join from the vertical box section) were found to influence the torsional properties of T-joints. Finally, an automotive T-component was analysed to examine the applicability of the T-joint results to more complex components.
15
Bhanu, Devi K., e Joseph Varghese. "Role of imaging in evaluation and management of juvenile idiopathic arthritis: a prospective cohort study". International Journal of Research in Medical Sciences 6, n. 11 (25 ottobre 2018): 3516. http://dx.doi.org/10.18203/2320-6012.ijrms20184214.
Testo completoAbstract (sommario):
Background: This study was aimed to evaluate the role of imaging in diagnosis and management of juvenile idiopathic arthritis by comparing the evaluation findings of clinical and ultrasound of all 14 joints in arthritis affected patients under 16 years of age.Methods: Prospectively study was done on patients in age group of 0-16years, who referred to radiology department based on clinical assessment. USG is done in both shoulder, elbow, wrist, hip, knee, ankle and subtalar joints of each patient to assess the following parameters Synovial hypertrophy, joint effusion, power doppler signal, tenosynovitis, enthesitis, cartilage thinning, bone erosions and bursitis.Results: Out of 980 joints assessed 344 joints (35.1% of all joints) had clinical synovitis, while USG evidence was in 382 joints (38.9% of all joints). Among the 344 clinically positive joints (35.1% of all joints), 223 joints (64.8%) had features of synovitis in USG and the rest 121 (35.2%) joints were clinically positive turned out to be ultrasound negative. Out of 980 joints 636 joints (64.8%) were clinically negative, of these 159 joints (25%) was found to have synovitis in ultrasound and 477 joints (75%) turned out to be negative on ultrasound examination.Conclusions: The sensitivity and specificity of ultrasound over clinical examination in shoulder joint was 47.6% and 89.1% respectively, in elbow joint 53.8% and 92.1%, in wrist joint 64.3% and 72.6%, in hip joint 65.1% and 64.9%, in knee joint 74.7% and 61.2%, in ankle joint 67.2% and 59.2% and in subtalar joint 56.7% and 71.8%, respectively.
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Kang, Hong-Tae, e Sai Boorgu. "Fatigue Life Prediction of Self-Piercing Rivet Joints Between Magnesium and Aluminum Alloys". MATEC Web of Conferences 165 (2018): 10004. http://dx.doi.org/10.1051/matecconf/201816510004.
Testo completoAbstract (sommario):
Various light materials including aluminum alloys and magnesium alloys are being used to reduce the weight of vehicle structures. Joining of dissimilar materials is always a challenging task to construct a solid structure. Self-piercing rivet (SPR) joint is one of various joining methods for dissimilar materials. Front shock tower structures were constructed with magnesium alloy (AM60) joined to aluminum alloy (Al6082) by SPR joints. To evaluate the durability performance of the SPR joints in the structures, fatigue tests of the front shock tower structures were conducted with constant amplitude loadings. Furthermore, this study investigated fatigue life prediction method of SPR joints and compared the fatigue life prediction results with that of experimental results. For fatigue life prediction of the SPR joints in the front shock tower structures, lap-shear and cross-tension specimens of SPR joint were constructed and tested to characterize the fatigue properties of the SPR joint. Then, the SPR joint was represented with area contact method (ACM) in finite element (FE) models. The load-life curves of the lap-shear and cross-tension specimens were converted to a structural stress-life (S-N) curve of the SPR joints. The S-N curve was used to predict fatigue life of SPR joints in the front shock tower structures. The test results and the prediction results were well correlated.
17
Wang, Hai Jun, Yong Yao, Yun Peng Chu e Dai Guo Chen. "Numerical Simulation on Beam-Column Joint in the Added-Layers Steel Structure under Monotonic Loading". Applied Mechanics and Materials 170-173 (maggio 2012): 3460–63. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.3460.
Testo completoAbstract (sommario):
Add layers for low-rise steel structure building can improve its using function. Use ANSYS analyze three added-layers beam-column joints of steel structure under the Monotonic loading. The results showed that: the joint reinforced by angles belongs to semi-rigid joint. Considering the construction and Structural requirements, the performance of this type joint is the most economical of all. The three joints all experience fully elastic deformation before them destructed, although the joint with only weld is deformation and failure, and the joint reinforced by haunched slab have larger deformability to resistance the plastic deformation, ultimate bearing capacity and initial stiffness, is one of the most conservative way of the joint’s reinforcement.
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Chu, Yun Peng, e Yong Yao. "Numerical Simulation Analysis on Seismic Behavior of Cold-Formed Beam-to-Column Connections". Advanced Materials Research 163-167 (dicembre 2010): 692–96. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.692.
Testo completoAbstract (sommario):
The cold-formed square steel tubular with light weight has better seismic behavior and is suitable for construction in the area with high seismic fortification intensity. The reliability of joint connection greatly influence the safety reliability of structure, which’s restoring force characteristics under low cyclic loading need to be further researched. The finite element software ANSYS is used to do the research between two welded joints. The results show that : (1)Compared with typical welded joint, the ultimate bearing capacity of improved joint increase much, hysteretic curve is more plump, energy dissipation capacity enhance and stiffness degradation is slow. (2) Axial compression ratio has great influence on hysteretic behavior, bearing capacity and stiffness of common welded joints; however, there is a little effect on improved joint’s bearing capacity and stiffness. (3) After improved, the yield of joint has a longer yield platform, and under the same axial compression ratio condition, its yielding and ultimate load both obviously superior to common welded joints.
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Lin, Jian, Yi Zhong e Yong Ping Lei. "Investigation on Joining Method Replacement for Vehicle Body’s Assembly". Advanced Materials Research 189-193 (febbraio 2011): 3621–24. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3621.
Testo completoAbstract (sommario):
Various joining methods (i.e., spot welding, arc welding, laser beam welding) have been used for vehicle body assembly. However it is unclear for the equivalent conversion of various joints which has the equivalent joint strength for the vehicle body, such as weld-bonded joint, SPR joint, which have been considered likely to replace RSW in the area of high strength steel’s joining. In order for the flexible design in the auto line of vehicles body’s joining, the equivalent (strength) weld pitch design method for various joints, including the joining of similar and dissimilar materials, is presented in this work. And some primary simulating results are presented and discussed. It is shown that the conversion method for various joints can be established based on the joint’s shear failure criteria. And the conversion results can be influenced by the sheet gage obviously. The failure criteria of various joint still need further investigation based on the simulating and experimental results.
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Wang, Xiuying, Ziqi Miao, Wenbiao Gong, Guipeng Lu, Juncai Sun, Yuqian Wang e Guangming Xie. "Enhanced Toughness and Ductility of Friction Stir Welded SA516 Gr.70 Steel Joint via Post-Welding Annealing". Materials 17, n. 1 (25 dicembre 2023): 116. http://dx.doi.org/10.3390/ma17010116.
Testo completoAbstract (sommario):
The SA516 Gr.70 steel possessing excellent toughness and plasticity has been widely used in the cryogenic field. However, the appearance of coarse bainite in the heat affected zone (HAZ) of the fusion welded joint deteriorates the toughness and ductility. In this work, 4.5 mm thick SA516 Gr.70 steel was joined using shielded metal arc welding (SMAW) and friction stir welding (FSW), respectively, and the microstructure and mechanical properties of joints were investigated in detail. The Charpy energy in the HAZ in the FSW joint was 80 J/cm2, which was higher than that of the HAZ in the SMAW joint (60 J/cm2) and due to microstructure refinement. In addition, the total elongation (TE) of the SMAW joint was 17.5%, which was higher than that of the FSW joint (12.1%) and caused by a wider nugget zone with high hardness. The post-welding annealing was used to improve the toughness and ductility of the SMAW and FSW joints, and the microstructure and mechanical properties of the joints after annealing were analyzed. The toughness in the HAZ of the SMAW and FSW joints were 80 and 103 J/cm2, and the TE of the SMAW and FSW joints were 18.6% and 25.2%, respectively. Finally, the as-annealed FSW joints exhibited excellent toughness and ductility. The abovementioned excellent mechanical properties were primarily attributed to the appearance of tempering martensite, decrease in dislocation density, and fine grain.
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KUMAR, Shailendra, Shikhar SHUKLA e Krishna KANT SHUKLA. "Rotational wood welding of Dalbergia sissoo wood: forming longitudinal tongue-and-groove and butt joints". BOIS & FORETS DES TROPIQUES 347 (25 marzo 2021): 5–11. http://dx.doi.org/10.19182/bft2021.347.a31865.
Testo completoAbstract (sommario):
Wood joinery is an essential part of woodworking for product manufacture. Wood sections are mostly joined together with adhesives. Wood welding brings a new dimension to joinery by using mechanical friction to induce a flow of wood components ensuring adhesion. In this study, a customized spin wood-welding machine was used to join wood sections of Dalbergia sissoo. Butt and tongue-and-groove joints were prepared and welded using the machine. The tensile strength of the joints was tested. The impact on joint strength of increasing the friction area by introducing tongue-and-groove joints was tested and analyzed. The tensile strength for butt joints at 1,200 rpm welding was estimated at 5.3 MPa. Joint strength was found to increase substantially (by 66%) with a tongue-and-groove welding section. Weld line temperatures at different spin times were also investigated. The aim of this study is to apply welding technology to Dalbergia sissoo to achieve greater joint strength.
22
Olaru, Ionel. "WELDED JOINTS STUDIES ON THE DEVELOPMENT OF BRAZED ALUMINUM SHEETS". International Journal of Modern Manufacturing Technologies 15, n. 2 (20 dicembre 2023): 137–42. http://dx.doi.org/10.54684/ijmmt.2023.15.2.137.
Testo completoAbstract (sommario):
Currently, the joints of different steel and aluminum materials are widely used for the manufacture of hybrid structures in the automotive field, in various naval constructions and transports mainly due to the need to reduce weight and achieve energy savings. The joining of aluminum sheets by welding or brazing means that two pieces are connected to each other through certain processes to form a whole and the structure thus created is of high performance. The materials chosen to make this type of welding-brazing are the result of laboratory analyses, they must be properly joined to be able to ensure the required strength of these joints. This work aims to study the realization of MIG welded-brazed joints of aluminum alloys with steel, which are complex joint structures that require high strength connections. The materials to be joined were chosen, a morphological analysis of the joint was carried out with the help of electronic microscopy, as well as various tensile tests to confirm the resistance of these joints.
23
Li, Jia Ke, Xin Liu e Jian Er Zhou. "Microstructure and Mechanical Performances of C/C Composite and TC4 Alloy Brazed Joints". Key Engineering Materials 512-515 (giugno 2012): 415–20. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.415.
Testo completoAbstract (sommario):
C/C composite and TC4 alloy were successfully brazed using 70Ag28Cu2Ti (wt. %) as filler metal at brazing temperature 820 º°C~920 °C for soaking time 5 min ~30 min. The effects of brazing parameters on the microstructures and phase composition and the fracture modes of the brazed joints were investigated by SEM and XRD. The mechanical performances of the brazed joints were measured by a universal mechanical testing machine. The results show that the maximum shear strength of the brazed joint is 28 MPa at brazing temperature 860°C and soaking time 10min. Fracture surface analysis of the brazed joints indicates that the position of the fracture surface is related to the orientation of carbon fiber. The brazed joints are fractured in the C/C composite when the carbon fiber is parallel to the joined surface, and the brazed joints are fractured at the C/C composite / 70Ag28Cu2Ti interface when the carbon fiber is vertical to the joined surface.
24
Wei, Yanni, Hui Li, Peng Xiao e Juntao Zou. "Microstructure and Conductivity of the Al-Cu Joint Processed by Friction Stir Welding". Advances in Materials Science and Engineering 2020 (27 luglio 2020): 1–10. http://dx.doi.org/10.1155/2020/6845468.
Testo completoAbstract (sommario):
In this paper, 1060 aluminum and T2 pure copper were joined by friction stir welding. The influence of the rotation speed and inclination on the microstructure and mechanical properties of the joint were investigated. The microstructure and composition of the welded interface region were analyzed. The joints’ strength was tested, and the conductivity of the joints was estimated. Joints having good surface formation and defect-free cross section were successfully obtained. The cross-sectional morphologies of the Al-Cu friction stir welding joints can be divided into three zones: the shoulder impact zone, the weld nugget zone, and the interface zone. The interface zone consisted of a metallurgical reaction layer and a visible mixed structure. The reaction layers were identified as Al2Cu, Al4Cu9 phases. The tensile strength of the joints reaches maximum values of 102 MPa at a rotation speed of 950 rpm and inclination of 0°, which was approximately equal to those of 1060Al base metal. The resistivity of the Al-Cu joint was approximately equal to the theoretical resistivity. The interfacial resistance is directly affected by the joint defects, compound types, and thickness of the intermetallic compound layer.
25
Chen, Lian-Meng, Kai-Yu Huang, Yi-Jie Liu, Ze-Bin Li, Yi-Hong Zeng, Wei Li, Yi-Yi Zhou e Shi-Lin Dong. "Analysis and Evaluation of the Progressive Collapse of Cable Dome Structures Induced by Joint Damage". Buildings 13, n. 8 (15 agosto 2023): 2072. http://dx.doi.org/10.3390/buildings13082072.
Testo completoAbstract (sommario):
The current literature lacks an effective progressive collapse analysis of a cable dome structure induced by joint damage. In this study, a dynamic analysis was performed using actual construction cases, an ANSYS LS-DYNA analysis platform, and a fully dynamic equivalent load instantaneous removal method. First, the structure’s dynamic responses and collapse modes induced by different joints with different types of damage were explored. Subsequently, joint importance coefficients were proposed depending on the structure’s displacement before and after joint removal, and the relationships between the joint importance coefficients and the joint properties and collapse modes, respectively, were then identified. Finally, the relationship between the joint damage and the connected component damage was explored. The results revealed that different joints and identical joints with different types induced a variety of dynamic responses. However, the dynamic response induced by the discontinuous joint damage was more apparent than that induced by the continuous joint damage. When a continuous joint model was used, the damage on all joints did not result in the progressive or local progressive collapse of the structure. Thus, all these joints were considered as common joints. However, when a discontinuous joint model was used, the failure of the joints resulted in three distinct collapse modes, namely a progressive collapse, a local progressive collapse, and a nonprogressive collapse, corresponding to the key joints, the important joints, and the common joints, respectively. These three types of joints corresponded to different importance coefficients. When damage occurred in the discontinuous joints separately linked to the key components, the important components, and the common components, the joints resulted in the progressive collapse, local progressive collapse, and nonprogressive collapse, respectively, of the structure.
26
Rudawska, Anna, Piotr Penkała, Paweł Chochowski, Andrzej Tkaczyk e Tetiana Vitenko. "Analysis of the strength of assembly joints - welded joints of various construction materials". Technologia i Automatyzacja Montażu 121, n. 3 (2023): 21–26. http://dx.doi.org/10.7862/tiam.2023.3.3.
Testo completoAbstract (sommario):
The aim of the article was to present issues related to the strength analysis of one of the types of assembly joints - welded joints, taking into account the influence of selected factors: technological - welding method, construction - type of joints and material - type of joined material. The MIG/MAG method (135/136), arc welding (111) and gas welding (311) were used as welding methods. Butt joints and lap joints were made of CuZn37 copper alloy (PN-EN 1652), S235JR unalloyed structural steel (EN 10025) and 1.4301 acid-resistant steel (EN 10088). Welded joints samples were made with appropriate parameters, according to the welding methods. Strength tests of welded joints on MTS BIONIX 370.02 testing machine, in accordance with the PN-EN 1465 standard Based on the obtained test results, it can be seen that the value of stresses and deformations is affected by both the welding method and the type of joint structure, while the type of material to be welded should also be taken into account.
27
Xiong, Zhihua, Yongjian Liu, Bin Liu e Lei Jiang. "Tension Strength Prediction of Transverse Branch Plate-to-Rectangular Joint with Concrete Filling". Frattura ed Integrità Strutturale 14, n. 54 (23 settembre 2020): 136–52. http://dx.doi.org/10.3221/igf-esis.54.10.
Testo completoAbstract (sommario):
This paper predicts the tension strength of Concrete-filled Branch Plate-to-Rectangular Hollow (CBPRH) joint by conducting experimental and theoretical analysis. A total of 46 X-joints with different geometric parameters were investigated, in which 4 specimens were tested under ultimate tension and 42 specimens were numerically analyzed. The joint’s strength, failure mode and load-displacement curve were obtained. Perfobond Leister Rib (PBR) was welded in part of the specimens to investigate its effect on joint’s tensile performance. It is shown that the ultimate strength of transverse CBPRH joint benefit from grouting of chord and installation of PBR. The ultimate strength of CBPRH joint with PBR is larger than the counterpart without PBR. Tension strength equations were proposed for both CBPRH joints with and without PBR by nonlinear regression. The chord axial stress reduction factor was discussed and a modified equation originated from hollow joint was recommended for CBPRH joint. Connection efficiency was presented and compared among branch plate-to-rectangular hollow (BPRH) joint, CBPRH joint and CBPRH joint with PBR.
28
Michael, Welch. "Bolted Joint Preload Distribution from Torque Tightening". Strojnícky časopis - Journal of Mechanical Engineering 71, n. 2 (1 novembre 2021): 329–42. http://dx.doi.org/10.2478/scjme-2021-0039.
Testo completoAbstract (sommario):
Abstract The purpose of this paper is to develop an understanding of how bolt preloads are distributed within a joint as each bolt is tightened in turn by the use of a calibrated torque wrench. It discusses how the order that the joints nuts/bolts are tightened can affect the final bolt preload. It also investigates the effect on incrementally increasing the bolt preload through a series of applications of the controlled torque tightening sequence. Classical analysis methods are used to develop a method of analysis that can be applied to most preloaded bolted joints. It is assumed that the static friction coefficient is approximately 15% less than the dynamic friction. It is found that the bolt preload distribution across the joint can range from slightly above the target preload to significantly less than the target preload. The bolts with a preload greater than the target preload are found to be those tightened towards the end of the tightening sequence, usually located close to the outer edges of the joint’s bolt array. The bolts with a preload less than the target preload are those tightened early in the tightening sequence, located centrally within the joints bolt array. The methods presented can be used to optimise bolted joint design and assembly procedures. Optimising the design of preloaded bolted joints leads to more efficient use of the joints.
29
Janeczek, Anna, Jacek Tomków e Dariusz Fydrych. "The Influence of Tool Shape and Process Parameters on the Mechanical Properties of AW-3004 Aluminium Alloy Friction Stir Welded Joints". Materials 14, n. 12 (11 giugno 2021): 3244. http://dx.doi.org/10.3390/ma14123244.
Testo completoAbstract (sommario):
The purpose of the following study was to compare the effect of the shape of a tool on the joint and to obtain the values of Friction Stir Welding (FSW) parameters that provide the best possible joint quality. The material used was an aluminium alloy, EN AW-3004 (AlMn1Mg1). To the authors’ best knowledge, no investigations of this alloy during FSW have been presented earlier. Five butt joints were made with a self-developed, cylindrical, and tapered threaded tool with a rotational speed of 475 rpm. In order to compare the welding parameters, two more joints with a rotational speed of 475 rpm and seven joints with a welding speed of 300 mm/min with the use of a cylindrical threaded pin were performed. This involved a visual inspection as well as a tensile strength test of the welded joints. It was observed that the value of the material outflow for the joints made with the cylindrical threaded pin was higher than it was for the joints made with the tapered threaded pin. However, welding defects in the form of voids appeared in the joints made with the tapered threaded tool. The use of the cylindrical tool resulted in higher values for about 37% of mechanical properties compared with the highest result for the tapered threaded joint. As far as the parameters were concerned, it was concluded that most of the specimens were properly joined for a rotational speed of 475 rpm. In the joints made with a welding speed of 300 mm/min, the material was not stirred properly. The best joint quality was given for a rotational speed of 475 rpm as well as a variety of welding speed values between 150 and 475 mm/min.
30
Su, Yi Sheng, Shu Fang Zheng, Qi Liang Li e Jin Yun Quan. "Experimental Study on the Static Performance of Joints in the Castellated Portal Frame of Light-Weight Steel". Applied Mechanics and Materials 166-169 (maggio 2012): 563–68. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.563.
Testo completoAbstract (sommario):
In order to study the mechanical behavior of joints in the castellated portal frame of light-weight steel under static loads, a static loads experiment has been performed for these new joints in this paper. The experiment members include four castellated joints and one solid-web joint of original steel, considering three vary parameters which are connection form of joints, joint region with setting stiffener and the distance from the center of hole to joint region. Experiment shows: the stiffness of castellated joints is higher than the one of solid-web joint. The parameters have a great influence on the mechanical behavior of joints, except the connection form of joints.
31
Godzimirski, Jan, Marek Rośkowicz, Michał Jasztal e Iga Barca. "Static and Fatigue Strength and Failure Mechanisms of Riveted Lap Joints of CFRP Composites". Materials 16, n. 5 (21 febbraio 2023): 1768. http://dx.doi.org/10.3390/ma16051768.
Testo completoAbstract (sommario):
The background of this work is the search for the most effective ways of joining composites, inter alia in aeronautical applications. The purpose of this study was to analyze the impact of mechanical fastener types on the static strength of lap joints of composite elements and the impact of fasteners on the mechanism of failure of such joints under fatigue load. The second objective was to check to what extent the hybridization of such joints, consisting of supplementing them with an adhesive joint, affects their strength and the mechanism of failure of such joints loaded with fatigue. Damage to composite joints was observed using computed tomography technology. The fasteners used in this study (aluminum rivets, Hi-lok and Jo-Bolt) differed not only in terms of the materials they were made of, but also in terms of the pressure forces they exerted on the joined parts. Finally, in order to check how a partially cracked adhesive joint affects the load on the fasteners, numerical calculations were carried out. Analyzing the results of the research, it was found that partial damage to the adhesive joint of the hybrid joint does not increase the load on the rivets and does not impair the fatigue life of the joint. An important advantage of hybrid joint is the two-stage destruction of the connection, which significantly increases the safety of aircraft structures and facilitates the process of supervising their technical condition.
32
Burke, Kathleen, e Shafik Bhalloo. "A Joint for the Joints". Journal of Business Ethics Education 14 (2017): 327–30. http://dx.doi.org/10.5840/jbee20171418.
Testo completo
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Hardi, Witono, Agus Sigit Pramono e Yohanes. "Performance of Tri-Adhesive Joints to Improve the Shear Stress Distribution of Lap Joints". Key Engineering Materials 941 (17 marzo 2023): 295–300. http://dx.doi.org/10.4028/p-7u96du.
Testo completoAbstract (sommario):
The adhesive lap joints are extensively used in various engineering fields. Various methods were proposed to increase the strength of the lap joint. This paper presents the lap joint's characterization by applying three grades of adhesives in different material properties along the bond line. The stiffest adhesive is employed in the middle bond line, then gradually, those with a lower modulus of elasticity are placed at the ends of the lap joint. This technique reduces the stress concentration at the joining ends, so the stress distribution becomes smoother. Finite element analysis is used to model this problem in two dimensions. One of the adherent edges is applied to the fixed support, and the other end is subjected to tension. The analysis results show that the use of tri-adhesive changes the shear stress distribution along the bond line flatter and increases the strength of tri-adhesive lap joints compared to those single type adhesive applied individually.
34
Vaziri, A., H. Nayeb-Hashemi e H. R. Hamidzadeh. "Experimental and Analytical Investigations of the Dynamic Response of Adhesively Bonded Single Lap Joints". Journal of Vibration and Acoustics 126, n. 1 (1 gennaio 2004): 84–91. http://dx.doi.org/10.1115/1.1596550.
Testo completoAbstract (sommario):
Dynamic response of single lap joints, subjected to a harmonic peeling load is studied theoretically and experimentally. In the theoretical part, dynamic response of a single lap joint clamped at one end and subjected to a harmonic peeling load at the other end is investigated. Adherents are modeled as Euler-Bernouli beams joined in the lap area by a viscoelastic adhesive layer. Both axial and transverse deformations of adherents are considered in deriving the equations of motion. The effects of adhesive layer thickness, mechanical properties and its loss factor on the dynamic response of the joint are investigated. Furthermore, effects of defects such as a void in the lap area on the dynamic response of the joints are studied. The results showed that frequencies where peak amplitudes occurred were little dependent on the adhesive loss factor. However, peak amplitudes reduced for joints with a higher adhesive loss factor. Furthermore, the results indicated that for the joint geometries and properties investigated the system resonant frequencies were not affected by the presence of a central void covering up to 80% of the overlap length. In the experimental part, single lap joints were fabricated using 6061-T6 Aluminum. Adherents were joined together using Hysol EA 9689 adhesive film. Joints with various central voids were manufactured by removing adhesive film from the desired area of lap joints prior to bonding adherents. Dynamic responses of the joints were investigated using the hammer test technique. The system response was measured using both an accelerometer and a noncontact laser vibrometer. The natural frequencies of the joints obtained by using the laser vibrometer were very close to those obtained theoretically. However, natural frequencies obtained by using an accelerometer depended on the accelerometer location in the system, which was attributed to its mass contribution to the over- all system mass. A central void covering less than 80% of the overlap length had little effect on the system resonance frequencies. This was in agreement with the theoretical results. In contrast total system-damping ratios were a function of the void size. Joints without a void exhibited higher damping.
35
Huan, Junhong, Tianyang Chu, Xiaodong Guo, Zemeng Sun, Xiaoyi Zhou, Wei Wang e Yating Yang. "Experimental study on seismic performance of Chinese traditional mortise and tenon joints with different lengths that tenons pull out of mortise". BioResources 19, n. 1 (21 novembre 2023): 478–99. http://dx.doi.org/10.15376/biores.19.1.478-499.
Testo completoAbstract (sommario):
This paper presents the results of a study on seismic performance of mortise-tenon joints with different lengths that tenons pull out of joints. Three 1:3.52 scaled mortise-tenon joint specimens were fabricated: one with through-tenon joints, one with half-tenon joints, and one with dovetail joints. Seismic data of the joints, such as hysteretic curves, skeleton curves, stiffness degradation rules, and energy dissipation capacity curves, were obtained by low-cycle reversed loading test. The influence of lengths that tenons pull out of joints on the mortise-tenon joints was analyzed. The seismic performance of three types of mortise-tenon joints was compared. The results showed that all hysteretic loops are z shaped. The seismic performance of the through joint was the best among three types of mortise tenon joint. The length that the tenon pulls out of the joint significantly affected the performance of the mortise and tenon joints.
36
Piotr, Lacki, e Niemiro-Maźniak Judyta. "Numerical and Experimental Analysis of Lap Joints Made of Grade 2 Titanium and Grade 5 Titanium Alloy by Resistance Spot Welding". Materials 16, n. 5 (1 marzo 2023): 2038. http://dx.doi.org/10.3390/ma16052038.
Testo completoAbstract (sommario):
The paper presents the evaluation of the load capacity of lap joints and the distribution of plastic deformations. The influence of the number and arrangement of welds on the load capacity of the joints and the method of their failure was investigated. The joints were made using resistance spot welding technology (RSW). Two combinations of joined titanium sheets were analyzed: Grade 2–Grade 5 and Grade 5–Grade 5. Non-destructive and destructive tests were carried out in order to verify the correctness of the welds within the given parameters. All types of joints were subjected to a uniaxial tensile test on a tensile testing machine, using digital image correlation and tracking (DIC). The results of the experimental tests of the lap joints were compared with the results of a numerical analysis. The numerical analysis was performed using the ADINA System 9.7.2 and was based on the finite element method (FEM). The conducted tests showed that the initiation of cracks in the lap joints occurred in the place as the maximum plastic deformations. This was determined numerically and confirmed experimentally. The number of welds and their arrangement in the joint affected the load capacity of the joints. Depending on their arrangement, Gr2–Gr5 joints with two welds reached from approximately 149 to 152% of the load capacity of joints with a single weld. The load capacity of the Gr5–Gr5 joints with two welds ranged from approximately 176 to 180% of the load capacity of joints with a single weld. Observations of the microstructure of RSW welds in the joints did not show any defects or cracks. The microhardness test in the Gr2–Gr5 joint showed that the average hardness of the weld nugget decreased by approximately 10–23% when compared to a Grade 5 titanium alloy and increased by approximately 59–92% compared to Grade 2 titanium.
37
Sadowski, T., T. Balawender, R. Sliwa, P. Golewski e M. Knec. "Modern Hybrid Joints in Aerospace: Modelling and Testing / Nowoczesne Połaczenia Hybrydowe W Lotnictwie: Modelowanie I Badania Eskperymentalne". Archives of Metallurgy and Materials 58, n. 1 (1 marzo 2013): 163–69. http://dx.doi.org/10.2478/v10172-012-0168-3.
Testo completoAbstract (sommario):
The aim of the paper is to review different types of modern hybrid joints applied in aerospace. We focused on three particular cases: 1) spot welding - adhesive, 2) rivet-bonded and 3) clinch-bonded joints. The numerical models presented in the paper for these joints describe their complex behaviour under mechanical loading. The numerical calculations performed using ABAQUS code were compared to experimental results obtained by application of the Digital Image Correlation system (DIC) ARAMIS. The results investigated within the paper lead to the following major conclusions: - the strengthening of joints by application of adhesive significantly improve static strength, - the final failure of the joined structural system significantly depends on the surface adhesive area, - the stiffening effects of the hybrid joint lead to higher reliability and durability of the structural joints.
38
Bukhsh, Ayman, Rawan Al Zahrani, Shaima Alqahtani, Abdulrahman Alsanea, Muflih Alanazi, Abdulrhman Atti, Hamzah Alwagdani et al. "Etiology and Clinical Management of Temporomandibular Disorders". Journal of Healthcare Sciences 02, n. 11 (2022): 422–28. http://dx.doi.org/10.52533/johs.2022.21114.
Testo completoAbstract (sommario):
Temporomandibular joints (TMJ) disorders are a group of morphological and functionally abnormal degenerative musculoskeletal problems. Limited or divergent movement, painful joint sounds, articular, muscular, or neural pain involving the joint are the hallmarks of the joint’s pathology. Temporomandibular disorders (TMD) have a broad spectrum. Various biological, environmental, social, and psychosomatic stimuli comprise the complex etiology of TMD. Mechanically induced remodeling, while progressive and regressive, is a physiological development initially. Osteoarthritis arises when the joint's rebuilding capability has been exceeded. The TMJ exhibits typical osteoarthritic changes, such as flattening of fossae, reduced pronunciation of articular eminence, reduced condyle proportions, and thicker disk. Decreased adaptability in the articular tissues or severe or recurrent physical stress on the joint’s tissues can also cause degenerative remodeling, that is noted in pathologic TMJs. It has been determined that non-invasive treatment options should be investigated first for patients looking to manage their temporomandibular disorders symptoms. However, there is a demand for more intrusive treatments because to the temporomandibular joint's complexity and the incapacitating nature of advanced-stage disease. Enhanced scope of movement, diminished synovitis, and the prevention of additional degeneration of joint surfaces are the foremost goals of the approaches used in managing TMD.
39
Witek, Lucjan. "INFLUENCE OF PLASTIC DEFORMATION OF ADHEREND MATERIAL ON STRESS DISTRIBUTION IN ADHESIVE LAP JOINTS". Acta Metallurgica Slovaca 23, n. 4 (4 dicembre 2017): 304. http://dx.doi.org/10.12776/ams.v23i4.1010.
Testo completoAbstract (sommario):
<p class="AMSmaintext">In the engineering analysis of adhesive lap joints the linear-elastic model of adherend material is often used. In some cases, when the joined material has a low yield stress, this assumption causes errors in stress estimation in the adhesive layer or adherend. In this study the results of numerical stress and strain analysis of single lap adhesive joints were presented. In performed analysis both the linear-elastic and the elastic-plastic models of adherend materials were considered. In the first part of the work the mechanical properties of joined material were obtained using the experimental investigations. In the next part of the work the discrete model of joint was created. The results of nonlinear finite element analysis showed that in the case of joining of materials with low yield stress the plastic deformation in adherend occurs at load much smaller than destructive force of the joint. In this kind of joints the plastic deformation of adherend influences a rapid stress increase in the adhesive layer, at the final stage of loading. This phenomenon causes a decrease of strength of single lap adhesive joints of elastic-plastic materials.</p>
40
Sieczkowski, Kamil, e Agnieszka Szczotok. "Effect of Preheating before Welding on the Microstructure and the Properties of SA213 T12 and SA387Gr11CL2 Steels Joints on the Example of a Sheet Piling". Solid State Phenomena 246 (febbraio 2016): 201–6. http://dx.doi.org/10.4028/www.scientific.net/ssp.246.201.
Testo completoAbstract (sommario):
The paper presents the results of the investigations of welded joints of the tube-flat bar type made of SA213 T12 and SA387Gr11CL2 steels. The joints were produced in two variants: 1) with heating up to 200°C, 2) without heating. The materials were joined by the submerged arc welding method. The temperatures of preheating before welding were determined, and it was verified whether the empiric relations (1) and (2), used to determine the minimal temperature of heating before welding for steel, can be applied under production conditions. The produced welded joints were evaluated quality-wise. Hardness measurements were performed in the particular joint areas. Finally, the effect of preheating on the obtained joints was compared.
41
Bailleul, Alida M., e Casey M. Holliday. "Joint histology in Alligator mississippiensis challenges the identification of synovial joints in fossil archosaurs and inferences of cranial kinesis". Proceedings of the Royal Society B: Biological Sciences 284, n. 1851 (22 marzo 2017): 20170038. http://dx.doi.org/10.1098/rspb.2017.0038.
Testo completoAbstract (sommario):
Archosaurs, like all vertebrates, have different types of joints that allow or restrict cranial kinesis, such as synovial joints and fibrous joints. In general, synovial joints are more kinetic than fibrous joints, because the former possess a fluid-filled cavity and articular cartilage that facilitate movement. Even though there is a considerable lack of data on the microstructure and the structure–function relationships in the joints of extant archosaurs, many functional inferences of cranial kinesis in fossil archosaurs have hinged on the assumption that elongated condylar joints are (i) synovial and/or (ii) kinetic. Cranial joint microstructure was investigated in an ontogenetic series of American alligators, Alligator mississippiensis . All the presumably synovial, condylar joints found within the head of the American alligator (the jaw joint, otic joint and laterosphenoid–postorbital (LS–PO) joint) were studied by means of paraffin histology and undecalcified histology paired with micro-computed tomography data to better visualize three-dimensional morphology. Results show that among the three condylar joints of A. mississippiensis , the jaw joint was synovial as expected, but the otherwise immobile otic and LS–PO joints lacked a synovial cavity. Therefore, condylar morphology does not always imply the presence of a synovial articulation nor mobility. These findings reveal an undocumented diversity in the joint structure of alligators and show that crocodylians and birds build novel, kinetic cranial joints differently. This complicates accurate identification of synovial joints and functional inferences of cranial kinesis in fossil archosaurs and tetrapods in general.
42
Khedr, Mahmoud, I. Reda Ibrahim, Matias Jaskari, Mohammed Ali, Hamed A. Abdel-Aleem, Tamer S. Mahmoud e Atef Hamada. "Microstructural Evolution and Mechanical Performance of Two Joints of Medium-Mn Stainless Steel with Low- and High-Alloyed Steels". Materials 16, n. 4 (15 febbraio 2023): 1624. http://dx.doi.org/10.3390/ma16041624.
Testo completoAbstract (sommario):
In this work, 2 mm thick medium-Mn austenitic stainless steel (MMn–SS) plates were joined with austenitic NiCr stainless steel (NiCr–SS) and low-carbon steel (LCS) using the gas tungsten arc welding technique. A precise adjustment of the welding process parameters was conducted to achieve high-quality dissimilar joints of MMn–SS with NiCr–SS and LCS. The microstructural evolution was studied using laser scanning confocal and electron microscopes. Secondary electron imaging and electron backscatter diffraction (EBSD) techniques were intensively employed to analyze the fine features of the weld structures. The mechanical properties of the joints were evaluated by uniaxial tensile tests and micro-indentation hardness (HIT). The microstructure of the fusion zone (FZ) in the MMn–SS joints exhibited an austenitic matrix with a small fraction of δ-ferrite, ~6%. The tensile strength (TS) of the MMn–SS/NiCr–SS joint is significantly higher than that of the MMn–SS/LCS joint. For instance, the TSs of MMn–SS joints with NiCr–SS and LCS are 610 and 340 MPa, respectively. The tensile properties of MMn–SS/LCS joints are similar to those of BM LCS, since the deformation behavior and shape of the tensile flow curve for that joint are comparable with the flow curve of LCS. The HIT measurements show that the MMn–SS/NiCr–SS joint is significantly stronger than the MMn–SS/LCS joint since the HIT values are 2.18 and 1.85 GPa, respectively.
43
Kaščák, Ľuboš, Emil Spišák e Jacek Mucha. "CLINCHRIVET AS AN ALTERNATIVE METHOD TO RESISTANCE SPOT WELDING". Acta Mechanica et Automatica 7, n. 2 (1 giugno 2013): 79–82. http://dx.doi.org/10.2478/ama-2013-0014.
Testo completoAbstract (sommario):
Abstract Various materials are used in car body production which are not always possible to join by conventional joining methods such as resistance spot welding. Therefore ClinchRivet method seem to be possible alternative. The paper deals with evaluation of properties of the joints made by mechanical joining method - ClinchRivet. The joint is made with the using of a special rivet, which is pushed into the joined materials by the flat punch. Following materials were used for joining of this method: DX51D+Z and H220PD steel sheets. The tensile test for observing the carrying capacities and metallographicall analysis were used for the evaluation of joint properties. Some results of the tests of ClinchRivet joints were compared to the properties of the joints made by resistance spot welding.
44
Qianzhong, Jia, Li Man, Qu Fuzheng e Zhang Hongtao. "Influence of Holding Time on Properties of Cemented Carbide-polycrystalline Diamond Compact Joints". Open Materials Science Journal 9, n. 1 (26 giugno 2015): 33–38. http://dx.doi.org/10.2174/1874088x01509010033.
Testo completoAbstract (sommario):
The influence of brazing holding time on properties of cemented carbide-polycrystalline diamond (PCD) compact joints were investigated in this study. The microstructure and phase composition of joints were investigated by scanning electron microscopy, electron probe microanalyzer, and X-ray diffraction. Microstructural investigations revealed the presence of Ag-based solid solution, Cu-based solid solution, Cu0.64Zn0.36, and a small amount of MnNi phase at the joint interface. The max shear strength of brazed joints 350.6 MPa was determined in the samples joined at 15 s, which was partially due to the dispersion strengthening effect of gray-black grains containing Cu-based solid solution, Cu0.64Zn0.36 and MnNi phase in the joints. Equal-area-circle grain diameter of the gray-black grains grew with longer holding time, whereas the shear strength decreased because of the formation of continuous intermetallic compounds layer along the joint boundary. Thermal damage of the PCD layer also deteriorated with increased holding time, and hence shorter holding time was preferable in the production.
45
Lin, Yongle, Xinwu Wang, Jian Gong, Shuren Wang, Haisu Sun e Huanhuan Liu. "Seismic Performance of an Exterior Joint between a Square Steel Tube Column and an H-Shape Steel Beam". Sustainability 15, n. 4 (20 febbraio 2023): 3856. http://dx.doi.org/10.3390/su15043856.
Testo completoAbstract (sommario):
This study developed a 1:2 scale model using T-shape steel with one-side bolts to connect a square steel tube column to an H-shape steel beam for a quasi-static test to investigate the mechanical properties and seismic behavior of semi-rigid joints. Within the study context, the joint’s failure characteristics, hysteresis characteristics, and strain tendency under cyclic load were determined. In addition, this research analyzed the force characteristics and seismic performance of such joints based on the test outcomes. In order to further study the seismic performance of such joints, ABAQUS finite element software was used to establish a numerical model and perform parametric analysis. The findings indicated that the force on both sides of the joint is inconsistent, resulting in different seismic performances on both sides of the joint. Selecting a T-shape steel connector significantly affects the seismic capacity of beam–column joints. The seismic capacity of joints can be improved by increasing the size of the T-shape steel. The stability of one-side bolts under repeated load is good, and their strain value rises steadily. Hence, this type of one-side bolt is suitable for connecting closed steel tube columns and other components. In general, the seismic performance of square steel tube column–H-shape steel beam joints with one-side bolts and a T-shape steel connection is good and is recommended for practical engineering.
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Lundkvist, Axel, Imad Barsoum, Zuheir Barsoum e Mansoor Khurshid. "Geometric and Material Modelling Aspects for Strength Prediction of Riveted Joints". Metals 13, n. 3 (1 marzo 2023): 500. http://dx.doi.org/10.3390/met13030500.
Testo completoAbstract (sommario):
The aim of this study is to develop a methodology for static strength and failure mode simulation of hot-driven riveted joints. The purpose is to be able to accurately estimate a rivet joint’s static strength behaviour and its failure mode without relying on experiments, to save both time and resources during the design of joints. The non-linear finite element analysis modelling framework considered the rivet joint configurations and geometry, the material properties of the plate and rivet as well as the clamping force of the hot-driven rivet. A ductile damage model was also implemented to capture the stress softening of the materials and the failure modes of the joints. Using experimental data from literature, the modelling framework is validated, and it is shown that it is able to capture the strength behaviour and failure modes of different configurations of rivet joints markedly well. The effect of the rivet pre-load on the mechanical response of the joint is also studied and it is shown that the strength of the joint increased with the increase in rivet pre-load. The modelling framework is then applied to an industrial component. The modelling framework is used to compare welding and riveting as joining methods in a component built in two grades of high-strength steel. It is found that the welded joint possessed greater strength compared to the proposed riveted joint. However, using the proposed simulation methodology developed, a riveted joint with matching strength to the welded joint could be designed.
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Vacek, John R., Troy S. Ford e Clifford M. Honnas. "Communication between the femoropatellar and medial and lateral femorotibial joints in horses". American Journal of Veterinary Research 53, n. 8 (1 agosto 1992): 1431–34. http://dx.doi.org/10.2460/ajvr.1992.53.08.1431.
Testo completoAbstract (sommario):
Summary Communications between the femoropatellar, medial femorotibial, and lateral femorotibial joints were studied, using fresh equine cadaver specimens. A total of 90 specimens from 45 horses were used. Horses were randomly assigned to 3 groups with 15 horses/group. Each group was assigned an injection site (femoropatellar joint, medial femorotibial joint, or lateral femorotibial joint), and red latex was injected into the respective location of each joint in each group. Immediately after injection, the joints were flexed and extended 100 times. The stifles were frozen in slight flexion, then cut into 1-cm sagittal sections. The communications between the femoropatellar and medial and lateral femorotibial joints were determined. None of the specimens in this study had communication between all 3 joint compartments. When the femoropatellar joint was injected, 18 of 30 joints (60%) communicated with the medial femorotibial joint, and 1 of 30 (3%) communicated with the lateral femorotibial joint. Injection of the medial femorotibial joint revealed 24 of 30 (80%) joints that communicated with the femoropatellar joint, and 1 of 30 (3%) that communicated with the lateral femorotibial joint. Injection of the lateral femorotibial joint resulted in communication with the femoropatellar joint in 1 of 30 (3%) joints. Communication did not exist between the medial and lateral femorotibial joints.
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Bechtel, Stephan, Rouven Schweitzer, Maximilian Frey, Ralf Busch e Hans-Georg Herrmann. "Material Extrusion of Structural Polymer–Aluminum Joints—Examining Shear Strength, Wetting, Polymer Melt Rheology and Aging". Materials 15, n. 9 (26 aprile 2022): 3120. http://dx.doi.org/10.3390/ma15093120.
Testo completoAbstract (sommario):
Generating polymer–metal structures by means of additive manufacturing offers huge potential for customized, sustainable and lightweight solutions. However, challenges exist, primarily with regard to reliability and reproducibility of the additively generated joints. In this study, the polymers ABS, PETG and PLA, which are common in material extrusion, were joined to grit-blasted aluminum substrates. Temperature dependence of polymer melt rheology, wetting and tensile single-lap-shear strength were examined in order to obtain appropriate thermal processing conditions. Joints with high adhesive strength in the fresh state were aged for up to 100 days in two different moderate environments. For the given conditions, PETG was most suitable for generating structural joints. Contrary to PETG, ABS–aluminum joints in the fresh state as well as PLA–aluminum joints in the aged state did not meet the demands of a structural joint. For the considered polymers and processing conditions, this study implies that the suitability of a polymer and a thermal processing condition to form a polymer–aluminum joint by material extrusion can be evaluated based on the polymer’s rheological properties. Moreover, wetting experiments improved estimation of the resulting tensile single-lap-shear strength.
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Bechtel, Stephan, Rouven Schweitzer, Maximilian Frey, Ralf Busch e Hans-Georg Herrmann. "Material Extrusion of Structural Polymer–Aluminum Joints—Examining Shear Strength, Wetting, Polymer Melt Rheology and Aging". Materials 15, n. 9 (26 aprile 2022): 3120. http://dx.doi.org/10.3390/ma15093120.
Testo completoAbstract (sommario):
Generating polymer–metal structures by means of additive manufacturing offers huge potential for customized, sustainable and lightweight solutions. However, challenges exist, primarily with regard to reliability and reproducibility of the additively generated joints. In this study, the polymers ABS, PETG and PLA, which are common in material extrusion, were joined to grit-blasted aluminum substrates. Temperature dependence of polymer melt rheology, wetting and tensile single-lap-shear strength were examined in order to obtain appropriate thermal processing conditions. Joints with high adhesive strength in the fresh state were aged for up to 100 days in two different moderate environments. For the given conditions, PETG was most suitable for generating structural joints. Contrary to PETG, ABS–aluminum joints in the fresh state as well as PLA–aluminum joints in the aged state did not meet the demands of a structural joint. For the considered polymers and processing conditions, this study implies that the suitability of a polymer and a thermal processing condition to form a polymer–aluminum joint by material extrusion can be evaluated based on the polymer’s rheological properties. Moreover, wetting experiments improved estimation of the resulting tensile single-lap-shear strength.
50
Guo, Jiaqi, Lipan Cheng, Yongbiao Lai, Yongchao Tian e Lu Li. "Study on Shear Mechanical Properties and Microscopic Failure Mechanism of Dentate Joints Based on DEM and Laboratory Tests". Buildings 12, n. 9 (19 settembre 2022): 1485. http://dx.doi.org/10.3390/buildings12091485.
Testo completoAbstract (sommario):
The stability control of the surrounding rock is greatly influenced by the rock joint’s shear mechanical characteristics and deformation failure mechanism. A numerical model of the dentate joints was created using a particle flow discrete element method (DEM). To study the shear mechanical behavior and damage evolution characteristics of the joints, a numerical simulation of the joints shear test under the same normal stress was conducted. Additionally, the joints’ shear failure mechanism and failure mode were investigated from a microscopic perspective in conjunction with laboratory tests. The results show that the shear strength steadily increases as the roughness of the rock joints increases and that it rapidly decreases after reaching its peak shear strength, indicating an obvious brittle failure. Varied rock joints exhibit significantly different micro-crack evolution, with rougher rock joints (r = 0.30, r = 0.37) exhibiting greater micro-crack production and crack extension into the model’s interior. Rock joint specimens with lower roughness (r = 0.17) had less concentration and fewer areas of contact force concentration. The shear failure mode of the rock joints gradually shifts from abrasion failure mode to snip failure mode as the roughness rises, which is largely compatible with the failure characteristics shown in the laboratory testing. The pattern of micro-crack development within the model specimen and the failure characteristics of the laboratory tests are in good agreement with the distribution characteristics of contact force on the rock joints.