Different Types Of Joints Research Articles

In-plane elasticity of regular hexagonal honeycombs with three different joints: A comparative study

This paper is focused on the in-plane linear elastic properties of regular hexagonal honeycombs with three different joint geometries: hexagonal joint, circular joint and triangular joint. A combination of theoretical and finite element (FE) methods was adopted to investigate their in-plane elastic moduli (Young's modulus, shear modulus and Poisson's ratio), and a good agreement between the two methods was obtained. The influences of the geometric parameters on the elastic moduli, such as ρ*/ρS and r/l, were fully discussed. Interestingly, a special relationship can exist among the three joint types, that is, the circular joint can be considered as a minimum circumscribed circle of the hexagonal and triangular joints. Based on this, a comparison among the honeycombs with three different types of joints was conducted. Compared to the conventional regular hexagonal honeycomb, the Young's modulus of the circular joint, hexagonal joint, and triangular joint honeycombs is enhanced by 61%, 80% and 431%, respectively; while the shear modulus is improved by 101%, 133% and 469%, respectively. Consequently, the triangular joint honeycomb was shown to be more successful in micro-structural layout compared with the other two types of honeycombs. This work could be a good guide for the design of novel cellular structures.

Testing Joints between Walls Made of AAC Masonry Units

Joints between walls are very important for structural analysis of each masonry building at the global and local level. This issue has often been neglected in the case of traditional joints and relatively squat walls. At present, the issue of wall joints is becoming particularly important due to the continuous drive for simplifying structures, introducing new technologies and materials. Eurocode 6 and other standards (American, Canadian, Chinese, and Japanese) recommend inspecting joints between walls, but no detailed procedures have been specified. This paper presents our own tests on joints between walls made of autoclaved aerated concrete (AAC) masonry units. Tests included reference models composed of two wall panels joined perpendicularly with a standard masonry bond (six models), with classic steel and modified connectors (twelve models). The shape and size of test models and the structure of a test stand were determined on the basis of the analysis of the current knowledge, pilot studies and numerical FEM (Finite Element Method) - based analyses. The analyses referred to the morphology and failure mechanism of models. Load-displacement relationships for different types of joints were compared and obtained results were related to results for reference models. The mechanisms of cracking and failure was found to vary, and clear differences in the behaviour and load capacity of each type of joint were observed. The individual working phases of joints were determined and defined, and an empirical approach was proposed for the determination of forces and displacement of wall joints.

JVS — Press review no. 2

Long-term obesity also affects the musculoskeletal system, mostly the joints, bones, muscles, tendons, and ligaments. Obesity damages the load-bearing tendons such as the patellar, Achilles, and plantar fascia. Obesity may also result in dislocations of the knee and causes multiple torn ligaments. Obesity may additionally be linked to chronic plantar heel pain. There are several different types of joints in the body. The synovial joints allow for motion, including flexion, extension, rotation, and abduction. These joints are divided into the ball and socket joints of the shoulders and hips, the hinge joints of the elbows and knees, the pivot joints of the atlas and axis, the condyloid joints of the wrists, the saddle joints of the thumbs, and the gliding joints of the fingers. The joints are affected by a variety of diseases, including osteoarthritis, rheumatoid arthritis, gout, and those of the vertebral column, often resulting in low back pain. Obesity is also linked to deteriorating bone density and muscle mass, resulting in a greater risk of falling and bone fractures. With obesity the adipocytes release bioactive peptides that affect connective tissues and damage their structure.

Flexural behavior of precast UHPC beam with prestressed bolted hybrid joint

Ultra-high performance concrete (UHPC) is suitable for precast and assembled bridges due to its unique characteristics. Therefore, an efficient, safe, and durable joint connection that fits between the precast UHPC beam segments is of crucial importance. In existing conventional prestressed joints, a potential safety hazard exists because steel strands corrode under long-term detrimental environmental conditions. To address this issue, a prestressed bolted hybrid joint was proposed in this study. Eight precast UHPC beams with different types of joints were constructed. Experimental tests were conducted to examine the flexural behavior and load-bearing mechanism of the prestressed bolted hybrid joint, prestressed joint, and bolted joint. The flexural capacity, characteristic loading values, deformation characteristics, and the failure modes of the three types of joints were investigated and the influences of the bolts and epoxy resin adhesive on the flexural capacity of the joints were also discussed. The test results showed that the failure of the hybrid joint was characterized by the local crushing of the UHPC at the top compression zone together with shearing off of some of the bolts. The flexural capacity of the hybrid joint was significantly improved and was 46.8–60.3% higher than that of the conventional prestressed joint. The overall flexural capacity of the hybrid joint can be divided into two parts, the contributions of the prestressed UHPC joint and bolted connection. The epoxy resin adhesive had little effect on the slip resistance of the bolted joint; however, its bonding effect increased the cracking moment and flexural capacity of the joint by 16.5–29% and 11.5–21.8%, respectively. Besides, due to the strengthening effect of the bolted steel plates and the prestressing, the overall stiffness of the UHPC beam with the hybrid joint was significantly higher than that of the prestressed joint and the bolted joint after joint opening. Based on the test results, a computational method was proposed for calculating the slip moment, joint-opening moment, and ultimate flexural capacity of the prestressed bolted hybrid joint and the prestressed joint, and the feasibility of the hybrid joint was verified.

Flexural Behaviours of Box Segmental Beams with Internal Tendons Subjected to Repeated and Static Loads

The main objective of this study is to gain a better understanding of the behaviours of different types of joints when box segmental beams are subjected to bending. Five beams with internal tendons were thus produced and tested: one beam was cast monolithically as a reference beam and four were formed as segmental beams. All beams were produced using Self Compacting-Concrete (SCC) in box sections. Each segmental beam was formed by assembling three precast concrete segments with four post tensioning tendons. The segmental beams had the same general characteristics, but with different types of joints between the segments. Four types of joints were adopted in this study;-dried, epoxied, dried strengthened with carbon fibres and multi-steel shear keyed joints. All beams were tested under two types of loadings, repeated and static. A test of repeated loading was carried out by exposing each specimen to three loading cycles. Each cycle was implemented by subjecting each specimen to up to 40% of the ultimate load then releasing the loads to return the specimen to the non-loading case. The test of static loading was carried out at the same rate of loading as the repeated load test, and all girder specimens were tested up to failure. The loads versus deflections at specified points were recorded for each 5 kN. Cracking, mode of failure and ultimate load values were recorded, along with the concrete surface strains at specified locations for both loadings. The tests results for repeated loading showed that joint type had a clear effect on behaviours in the segmental beams, which had deflection readings ranging from 16 to 61% higher than that of the monolithic (reference) beam, as well as higher tensile strain than seen in the reference beam, by 8 and 67%. Similar effects of joint type were observed under static test. At the first crack loading, the segmental beams had deflections of between 8 and 94% and tensile strains of about 5 to 18% more than the reference beam. The failure modes of the tested beams were all different. Failure of the dry joint occurred in the segment interface, while the failure of each epoxied joint and joint strengthened by carbon fibres developed in the concrete adjacent to the segment interface. The steel shear keys clearly transfer the shear resistance to the concrete parts adjacent of the joints.

RETRACTED: Ecofriendly energy efficient welding of aluminium matrix composites for aerospace applications: A state of art review

Abstract Friction Stir Welding (FSW) is one of the welding technique which is growing globally to weld Aluminium Matrix Composites (AMCs). FSW is a solid-state welding process in which temperature of the material to be joined does not exceed its melting temperature and in which properties of the parent material does not change. Friction stir welding process helps in eliminating the defects of conventional welding processes such as Fusion welding, Arc welding & Friction welding etc. Apart from conventional welding process, FSW is considered to be an eco-friendly process because it does not create fumes, gases or smoke and uses low energy which makes FSW different from conventional welding processes. FSW is applied in the fabrication of different type of joints like butt joint, lap joint or combination of both, fillet joint, etc. successfully on AMCs. Apart from Al alloys, other light metal alloys like Cu alloys, Mg alloys, Zn, and Pb can also be joined through FSW. Nowadays, the application of FSW has widened in different industries like aerospace, shipbuilding, automotive, modern railways, fabrication of titanium, etc. The Aerospace industry is using FSW at major scale to join mainly AMCs (lightweight property). This paper gives an overview of the FSW to weld AMCs, and how process parameters effect the mechanical, macrostructure and microstructural properties of the joint. The paper also highlights the wear state of the FSW tool and ways to overcome them.

Role of Notch Signaling in Leg Development in Drosophila melanogaster.

Notch pathway plays diverse and fundamental roles during animal development. One of the most relevant, which arises directly from its unique mode of activation, is the specification of cell fates and tissue boundaries. The development of the leg of Drosophila melanogaster is a fine example of this Notch function, as it is required to specify the fate of the cells that will eventually form the leg joints, the flexible structures that separate the different segments of the adult leg. Notch activity is accurately activated and maintained at the distal end of each segment in response to the proximo-distal patterning gene network of the developing leg. Region-specific downstream targets of Notch in turn regulate the formation of the different types of joints. We discuss recent findings that shed light on the molecular and cellular mechanisms that are ultimately governed by Notch to achieve epithelial fold and joint morphogenesis. Finally, we briefly summarize the role that Notch plays in inducing the nonautonomous growth of the leg. Overall, this book chapter aims to highlight leg development as a useful model to study how patterning information is translated into specific cell behaviors that shape the final form of an adult organ.

The experimental and numerical analysis of the adhesively bonded three-step-lap joints with different step lengths

Adhesive bonding is one of the most used joining methods for bonding composite or different types of materials. The joint type commonly used in adhesive bonding is the single lap joint (SLJ) type. However, in adhesively bonded joins, peel stress occurs due to the eccentric loading, which causes damage to the ends of the overlap area. Different types of joints are used to reduce these peel stresses. One of these joint types is the step-lap joint type obtained by creating steps in the overlap area. In this study, mechanical properties of the single lap joint (SLJ), one-step lap joint (OSLJ) and three-step lap joint (TSLJ) with five different step lengths subjected to tensile loading were examined experimentally and numerically by keeping the bonding area same for all samples examined. In this experimental study, AA2024-T3 aluminum alloy was used as the adherend and DP460, a structural adhesive with two components, was used as the adhesive. In addition, the progress of the crack in the overlap area was observed with a high-speed camera. As a result, the TLSJ type was found to carry more load than other joint types. Also, the change in the step length in the three-step lap joint type had a significant effect on the failure load of the joint. When the failure loads obtained in the experiments and the numerical analysis were examined, it was concluded that their results were quite compatible with each other when the cohesive zone model was used in the numerical analysis. Another result obtained from the study is the optimum length of the first step created at the ends of the overlap area in the three-step lap joint.

Weak coupling of nonlinear isogeometric spatial Bernoulli beams

This paper proposes a coupling scheme for isogeometric elements, which is valid for large rotations and displacements. Two elements can be coupled not only at interpolated control points but also inside the parametric domain of a NURBS patch. Furthermore, each cross section may be arbitrarily oriented in space. The formulation is applicable for all structural elements, where an orthogonal system of base vectors can be derived. An Euler–Bernoulli beam is used as an example in order to illustrate the demands on the coupling conditions in the proposed approach. Moreover, the conditions are chosen such that different types of joints, e.g. scissor joints, can be modeled and such that they are easy and fast to implement. The coupling is incorporated by an additional term in the Principle of Virtual Work which is here computed using a penalty approach. The Euler–Bernoulli beam is summarized in order to introduce the notations in this contribution. This is followed by the proposed coupling conditions in the weak form. Subsequently, alternatives for the coupling conditions are briefly introduced. Eventually, benchmark and demonstrator examples validate and illustrate the proposed coupling methodology.

Fractographic analysis of the hygrothermal effect in co-bonded and secondary bonded joints under mode II delamination loading

Adhesive bonding technologies exhibit several advantages over conventional mechanical fasteners which include lower weight, reduced stress concentration in the adherents and excellent fatigue properties allowing the design of smooth surface contour and damage tolerant aerostructures. The overall structural performance of the composite joint depends on several factors related to the manufacturing process, such as surface preparation procedure, adhesive type, aging effects, and deficiency of inspection procedures. For this reason, there is a clear need to understand better how the joints behavior can be affected by them and the causes of their failure in order to improve the design and performance. In this context, this work presents the application of Scanning Electron Microscopy (SEM) technique to perform the fractographic analysis in two different types of joints namely co-bonded (CB) and secondary bonding (SB) that were submitted to a interlaminar fracture toughness tests under Mode II loading at Room Temperature Ambient (RTA) and Environmental Temperature Wet (ETW) conditions. The fracture surface of each sample submitted Mode II was prepared and analyzed regarding its failure aspects, enabling their association with the mechanical behavior of the samples during the fracture toughness tests and the values obtained. A detailed study on the fracture aspects of the composite joints was carried out correlating the fracture aspects with the mechanical behavior, type of processing and environmental conditioning in which each type of joint was tested, thus validating the use of these joints for operating conditions similar to those experienced in-service concerning aeronautical applications.

Static and Fatigue Characteristics of Pinned Metal-Composite Joints

Metal-composite joining methods currently rely almost exclusively on the adhesive bonding, the application of mechanical fasteners or a combination of the methods, the pros and cons of which are well known. In this article, a manufacturing-oriented solution for increasing the static and fatigue characteristics of metal composite bolted T-joints loaded in the out-of-plane direction by reinforcing the composite basement with a thin metal plate having die cut pins is proposed. Static load–displacement and fatigue life curves were obtained experimentally for different types of joints. The results obtained showed that, for a fiberglass/epoxy laminate, the solution proposed increased its static and fatigue failure loads by 64 and 50% respectively. It was also found that pinned adhesive joints were more effective than the conventional bolted ones at high-cycle loadings (the number of cycles exceeded 104).

Interplay of Wettability, Interfacial Reaction and Interfacial Thermal Conductance in Sn-0.7Cu Solder Alloy/Substrate Couples

Directional solidification experiments coupled with mathematical modelling, drop shape analyses and evaluation of the reaction layers were performed for three different types of joints produced with the Sn-0.7 wt.%Cu solder alloy. The association of such findings allowed understanding the mechanisms affecting the heat transfer efficiency between this alloy and substrates of interest. Nickel (Ni) and copper (Cu) were tested since they are considered work piece materials of importance in electronic soldering. Moreover, low carbon steel was tested as a matter of comparison. For each tested case, wetting angles, integrity and nature of the interfaces and transient heat transfer coefficients, ‘h’, were determined. Even though the copper has a thermal conductivity greater than nickel, it is demonstrated that the occurrence of voids at the copper interface during alloy soldering may decrease the heat transfer efficiency, i.e., ‘h’. Oppositely, a more stable and less defective reaction layer was formed for the alloy/nickel couple. This is due to the suppression of the undesirable thermal contraction since the hexagonal Cu6Sn5 intermetallics is stable at temperatures below 186°C in the presence of nickel.

Arthroplasty at the proximal interphalengeal joint

For the treatment of deformed finger middle joints that occur as aresult of osteoarthritis or inflammatory and post-traumatic destruction, artificial joint replacement is an option to arthrodesis. Hereby mobility can be obtained, which is why this method generally has ahigher acceptance. What clinical and subjective results can be expected after artificial finger middle joint replacement and what is the expected complication rate for the different types of joints? We present our experiences with artificial joint replacement with various implants over the past decades as well as promising new developments of the last 10years. The silicone implant still remains the gold standard in joint replacement. For these implants, good long-term results and low revision rates have been documented. Due to the soft flexible material, however, lateral stability and preoperatively-existing axis deviations seem problematic. Initial studies with modular resurfacing implants appear promising and may eventually replace the silicone spacer over the long term. Consequently, long-term results of these modern implants are pending. Painful osteoarthritis of the finger joint can be treated well with motion-preserving artificial joints. The complication rate appears to be decreasing. New generation modular surface prostheses seem to be relatively equal to the silicone spacer in terms of long-term outcomes.

Numerical model for the non-linear dynamic analysis of multi-storey structures with semi-rigid joints with specific reference to the Algerian code

The current paper aims at investigating the dynamic response of rigid and semi-rigid connections of steel structures built in high seismic areas. A nonlinear dynamic analysis model, which is an extension to the simplified and direct mechanical model used in the static analysis, is proposed and discussed. The novelty of the model consists in the introduction of a bar element with semi-rigid joint as a single element without the need to discretise it (i.e. without a finite element mesh) in the program where non-linearity is considered in the flexibility factor of the stiffness matrix. The model developed is validated through application to examples of steel frames with different types of connections under dynamic forces. The results obtained were very satisfactory. This work is motivated by the need for the revision of the Algerian seismic code (RPA99v2003) which does not yet consider provisions for the design of structures with semi-rigid joints. Based on the results of the study carried out on a multi-storey structure with different types of joints subjected to seismic loading, it can be seen that the safety justifications recommended by Algerian regulations RPA99 in terms of relative displacements as well as the dimension of the seismic joint prove to be too conservative compared to those by Eurocode 8.

An efficient finite element formulation of dynamics for a flexible robot with different type of joints

If two adjacent links of a flexible robot are connected via a revolute joint or a fixed prismatic joint, the relative motion of the next link will depend on both the joint motion and the elastic displacement of the distal end of the previous link. However, if the two adjacent links are connected via a sliding prismatic joint, the relative motion of the next link will depend additionally on the elastic deformation distributed along the previous link. Therefore, formulation of the motion equations for a multi-link flexible robot consisting of the revolute joints, the fixed prismatic joints and the sliding prismatic joints is challenging. In this study, the finite element kinematic and dynamic formulation was successfully developed and validated for the flexible robot, in which a transformation matrix is proposed to describe the kinematics of both the joint motion and the link deformation. Additionally, a new recursive formulation of the dynamic equations is introduced. As compared with the previous methods, the time complexity of the formulation is reduced by O(2η), where η is the number of finite elements on all links. The numerical examples and experiments were implemented to validate the proposed kinematic and dynamic modelling method.

Analysis of different types of bolted joints for i-beams and their comparative laboratory research

The article considers the results of laboratory tests for different types of bolted joints for the I-beams. The tests were subjected to a steel I-beam cross section with splice joint by friction, flange and combination of the splice joint by friction and flange joints under a bending. A brief review and analysis of existing solutions for bolted joints for girders are given, the main difficulties with the use of welded joints and bolted joints are indicated. The results of laboratory tests of different types of bolted joints for I-beams, using high-strength bolt connections, are presented. The pictures of stress distribution in the elements of joints are investigated, and the deflections of beams using different types of joints are determined. It is shown that the deflections of beams with splice joints are significantly influenced by the ductility of the entire connection. According to the test results, the conclusions about the obtained pliability values are made and the graphs of joint deformation at various stages of loading are given. The obtained pliability values may be used in further virtual experiments.

Relationship between hospital or surgeon volume and outcomes in joint arthroplasty: protocol for a suite of systematic reviews and dose–response meta-analyses

IntroductionJoint arthroplasty is a particularly complex orthopaedic surgical procedure performed on joints, including the hip, knee, shoulder, ankle, elbow, wrist and even digit joints. Increasing evidence from volume–outcomes research supports...

Analysis of different types of bolted joints for i-beams and their comparative laboratory research

The article considers the results of laboratory tests for different types of bolted joints for the I-beams. The tests were subjected to a steel I-beam cross section with splice joint by friction, flange and combination of the splice joint by friction and flange joints under a bending. A brief review and analysis of existing solutions for bolted joints for girders are given, the main difficulties with the use of welded joints and bolted joints are indicated. The results of laboratory tests of different types of bolted joints for I-beams, using high-strength bolt connections, are presented. The pictures of stress distribution in the elements of joints are investigated, and the deflections of beams using different types of joints are determined. It is shown that the deflections of beams with splice joints are significantly influenced by the ductility of the entire connection. According to the test results, the conclusions about the obtained pliability values are made and the graphs of joint deformation at various stages of loading are given. The obtained pliability values may be used in further virtual experiments.

Spacecraft Robot Kinematics Using Dual Quaternions

In recent years, there has been a growing interest in servicing orbiting satellites. In most cases, in-orbit servicing relies on the use of spacecraft-mounted robotic manipulators to carry out complicated mission objectives. Dual quaternions, a mathematical tool to conveniently represent pose, has recently been adopted within the space industry to tackle complex control problems during the stages of proximity operations and rendezvous, as well as for the dynamic modeling of robotic arms mounted on a spacecraft. The objective of this paper is to bridge the gap in the use of dual quaternions that exists between the fields of spacecraft control and fixed-base robotic manipulation. In particular, we will cast commonly used tools in the field of robotics as dual quaternion expressions, such as the Denavit-Hartenberg parameterization, or the product of exponentials formula. Additionally, we provide, via examples, a study of the kinematics of different serial manipulator configurations, building up to the case of a completely free-floating robotic system. We provide expressions for the dual velocities of the different types of joints that commonly arise in industrial robots, and we end by providing a collection of results that cast convex constraints commonly encountered by space robots during proximity operations in terms of dual quaternions.

Investigation of Mesh Size Effect on Dynamic Behaviour of an Assembled Structure with Bolted Joints using Finite Element Method

The predicted results of the finite element (FE) model of an assembled structure with different types of joints are highly dependent on the mesh size of the FE model. The complexity of the FE model has forced engineers to seek the most efficient techniques for the selection of the appropriate mesh size specifically in obtaining accurate predicted results in normal modes analysis. This paper concerns the investigation into the effects of the mesh sizes and selection technique of the appropriate mesh size in the FE modelling and analysis of the assembled structure with bolted joints. The investigation was carried out by predicting the modal parameters of the FE models with the predefined range of mesh sizes. The predicted results of the FE models were compared with the measured counterparts obtained from the experimental modal analysis (EMA). The total error obtained from the comparison between FE and EMA was recorded. Evaluations were made by comparing the number of nodes and elements of the FE models, percentage of total error, computer processing unit (CPU) elapsed time and memory usage. The outcomes of the evaluations showed that there are significant effects of the mesh sizes on the accuracy, computing time and memory usage of the FE modal analysis of the assembled structure with bolted joints. This work also demonstrated an efficient technique for the selection of the appropriate mesh size in achieving a reliable, efficient and economic FE modelling and analysis of the assembled structure with bolted joints.