Joint Size Research Articles

Size effect of bonded area for bonded joints between ETICS with an acrylic thin-film plaster and sheet metal component

The issue of anchoring sheet metal components has been part of construction practice for a very long time. Sheet metal components can be found on most contemporary buildings and due to the increasing thickness of insulation the possibility of anchoring to the supporting substrate is a problem. This paper discusses the issue of the bonded joint size dependence on the load capacity for fastening sheet metal elements to ETICS facades. A thixotropic silane modified polymer adhesive was used for this research. It was concluded that the size has a significant effect on the load capacity of the joint and their dependence was described.

Effect of tool pin profiles on fatigue crack growth rate of friction stir welded joint of Al alloy 7075-T651

ABSTRACT In the current study, the effect of different tool pin profiles on fatigue crack growth rate, tensile strength, microstructural behaviour, and microhardness of friction stir welded joints of AA7075-T651 was studied. The friction stir welding joints known as J1 and J2 were formed using two different tool pin profiles: square pin tool profiles and left-hand threaded cylindrical tool pin tool profiles. All pin profile has scrolled shoulder. The results showed that the fatigue crack growth rate for the J2 joint was lesser than that of J1 joint, whereas the average grain size of J2 joint was lower than the J1 joint which led to the higher tensile strength of the J2 joint when compared to the J1 joint. Both joints were found to have residual stresses that were compressive in the longitudinal direction. The grain size of the weld nugget zone, internal residual stresses and strengthening precipitates impede the fatigue crack growth rate. The crack closure and non-homogenous microstructure play an important role in the variation of the fatigue crack growth rate.

Numerical modelling of bond behavior between rebar and high-strength fiber-reinforced cementitious composites (HSFRCC) for inter-module joint in modular construction

In modular construction, the optimization of joint design has always been a major challenge. The joint size is primarily governed by rebar-concrete bond strength, as tensile stress is transferred from one lapped bar to the other through the concrete substrate. The complex mechanism of rebar-concrete bond degradation is dependent on both the property of the bonded interface and the damage of surrounding concrete. By virtue of its exceptional mechanical performance that contributes to the enhancement in rebar bond property, high-strength fiber-reinforced cementitious composites (HSFRCC) are often adopted in precast construction to locally replace conventional concrete in the joint area. In a previous study, the authors explored the application of HSFRCC in modular construction and developed a novel inter-module joint design. Based on the mechanical properties of the materials and the explicit geometry of the bonded interface, a 3D finite element model was introduced and showed good agreement with pull-out test results. Building on the preceding works, this paper aims to further validate the numerical model and demonstrate its general applicability using HSFRCCs with different steel fiber content. With the validated model, the effects of rebar bond length, HSFRCC cover thickness, and thickness of steel plate confinement on the bond performance are investigated in parametric studies, which establishes the basis for formulating a rational design approach for the proposed joint method.

Numerical study of temperature–pressure coupling model for the horizontal well with a slim hole

AbstractHorizontal wells with a slim hole (HW‐SH), characterized by high productivity, high environmental protection, and low cost are gradually being introduced into oil and gas extraction processes in high‐temperature and high‐pressure formations. However, the HW‐SH annulus is narrow, and the distributions of temperature and pressure in the wellbore are very different from those of conventional horizontal wells. Furthermore, the mud properties change under the influence of high temperature and pressure. In this study, a numerical model of the transient temperature‐pressure coupling field in an HW‐SH wellbore was developed based on high‐temperature and high‐pressure performance tests of mud, combined with the characteristics of a narrow annulus in HW‐SH. Subsequently, the effects of the ground temperature gradient, displacement, drill pipe speed, annulus size, and joint size on the temperature‐pressure coupling field were analyzed. Measured data from the HW‐SH drilled in the Mahu field in China were used to validate the developed model. The results showed that the ground temperature had a significant effect on the mud density and rheological properties. As the temperature increased, the mud density decreased, and its rheological properties improved. Although pressure also has a large effect on density, it has a negligible effect on the rheological properties of the mud. The coupled temperature‐pressure field model for HW‐SH considering the effects of the temperature and narrow annulus can predict the annulus temperature and pressure with an accuracy of up to 97%. The ground temperature gradient has the greatest influence on the HW‐SH annular temperature, larger than that of the displacement. In addition, the annular size, rotation speed of the drill pipe, and joint size have almost no influence on the annular temperature. Compared to those of conventional horizontal wells, the rotational speed, annulus size, and joint size of the HW‐SH have a greater impact on the annulus pressure.

Microstructure and Texture Characterization of Duplex Stainless Steel Joints Welded by Alternating Magnetic Field-Assisted Hybrid Laser-GMAW Welding.

In this study, 2205 duplex stainless steel with 12 mm thickness was welded by alternating magnetic field-assisted laser arc hybrid welding. The effect of an alternating magnetic field on the proportion distribution of two phases of the welded joint was investigated. The texture distribution, grain boundary misorientation, and grain size of welded joints were analyzed and characterized. The uniform distribution of alloying elements in the two phases was improved by a 20 mT alternating magnetic field. The diffusion dissolution of Ni and N elements into the γ phase was promoted, which was conducive to the transition from the α to γ phase and reduced the precipitation of Cr2N, such that the ratio of γ to α was 43.4:56.6. The ratio of the two phases of the weld was balanced by the alternating magnetic field of 30 mT, such that the ratio of γ and α was 44.6:55.4 and the texture dispersion was weakened. The Σ3 twinning boundary of the austenite phase in the weld was transformed to HABs, the ferrite phase underwent dynamic recrystallization, and the austenite phase had a cube texture, copper texture, and goss texture.

Applicability Evaluation of Nano-Al2O3 Modified Sn-Ag-Cu Solder in High-Density Electronic Packaging Subjected to Thermal Cycling

Recently, 3D packaging has been regarded as an important technical means to continue Moore’s Law. However, excessive stacking will increase the longitudinal dimension, and one chip with high-density bondings packaging is still needed. Thus, it naturally places higher demand on thermal cycling reliability due to the decreased joint size to satisfy high-density packaging. In this work, the nano-Al2O3 (1 wt.%) modified Sn-1 wt.% Ag-0.5 wt.% Cu low-Ag solder was applied as a solder sample to evaluate the associated thermal cycling reliability. The investigated results revealed that the nano-Al2O3 modified solder did present enhanced thermal cycling reliability, as evidenced by the delayed microstructure coarsening and the inhibited atom inter-diffusion at interface caused by the adsorption of nano-Al2O3 on grain surfaces, and the resultant pinning effect. Worthy of note is that the potential of the newly developed nano-Al2O3 modified solder for high-density packaging applications (e.g., BGA, QFN, and CCGA) was evaluated based on the Finite Element Modeling.

Influence of solder condition on effective thermal conductivity of two-directional random fibres: Pore-scale simulation

It is indicated that the solder joint of the metal fibrous materials is a critical factor impacting the heat conduction. To reveal the mechanism by which solder joint sizes, solder joint skips, solder flux materials, and filling media affect the thermal conductivity of fibres, pore-scale numerical simulation is employed to study the thermal transport in two-directional (2-D) random fibres. Satisfactory agreement with existing data validates the numerical model. The dimensionless effective thermal conductivity (ETC) of the porous fibres increases with the solder joint sizes. As the solder joint size (i.e., solder joint ratio) increases by 3.06%, the in-plane (ke-in) and out-of-plane (ke-out) dimensionless ETC increase by 9.0% and 437.2%, respectively. However, the solder joint skips will weaken the thermal conductivity of the fibres. For the same fibre, the ETC of the fibre increases as the thermal conductivity of solders increases. Further, when the dissimilarity in thermal conductivity between the filling medium and the fibre is reduced, the fibre is less affected by the solder joint skips. Finally, it should be supplemented that the in-plane and out-of-plane ETC (ke-in and ke-out) of the fibre without any solder joint are reduced by an average of 14.3% and 98.8%, respectively.

High spatial resolution analysis using automated indentation mapping differentiates biomechanical properties of normal vs. degenerated articular cartilage in mice.

Characterizing the biomechanical properties of articular cartilage is crucial to understanding processes of tissue homeostasis vs. degeneration. In mouse models, however, limitations are imposed by their small joint size and thin cartilage surfaces. Here we present a three-dimensional (3D) automated surface mapping system and methodology that allows for mechanical characterization of mouse cartilage with high spatial resolution. We performed repeated indentation mappings, followed by cartilage thickness measurement via needle probing, at 31 predefined positions distributed over the medial and lateral femoral condyles of healthy mice. High-resolution 3D x-ray microscopy (XRM) imaging was used to validate tissue thickness measurements. The automated indentation mapping was reproducible, and needle probing yielded cartilage thicknesses comparable to XRM imaging. When comparing healthy vs. degenerated cartilage, topographical variations in biomechanics were identified, with altered thickness and stiffness (instantaneous modulus) across condyles and within anteroposterior sub-regions. This quantitative technique comprehensively characterized cartilage function in mice femoral condyle cartilage. Hence, it has the potential to improve our understanding of tissue structure-function interplay in mouse models of repair and disease.

Effect of Joint Size on Creep Behavior of Sn-Ag-Cu Solder-Cu Joints

Effect of Joint Size on Creep Behavior of Sn-Ag-Cu Solder-Cu Joints

Shear deformation behavior and failure mechanisms of graphene reinforced Sn-based solder joints bonded by transient current

Graphene as a reinforcement is expected to improve the shear strength of solder joint. However, little is known about the deformation behavior and mechanisms of composite solder joints. In this study, sandwich joints are prepared using graphene nanosheets-reinforced Sn-Ag-Cu composite solder (GNSs/SAC) by transient current bonding technology in order to obtain dispersed graphene. Interrupted shear tests combined with orientation image microscopy are conducted at different strain to observe the morphology and crystal orientation evolution of solder joints in situ. Some twins rotate, and the orientation begins to spread during shear, while the orientation of large Sn grain shows a minimal change. Cracks tend to initiate and propagate along the boundary. The failure mechanisms of the solder joint is determined. Molecular dynamics results show that the strain concentration at the boundary. Continuous shear tests show that the shear strength was improved by approximately 50.7% with the addition of 0.1 wt% graphene. Based on microstructure analysis and calculation, load transfer is identified as the dominant strengthening mechanism for GNSs/SAC alloys, followed by Orowan system. Graphene does not refine the grain size of solder joints, and dislocation multiplication from thermal mismatch does not strengthen them.

A hydraulic actuator for joint robots with higher torque to weight ratio

AbstractJoint actuators with a compact size and high power density are necessary for robots with rotating joints, making the hydraulic actuator (HyA) an ideal actuator candidate. This paper presents a joint HyA with the following characteristics: compact installation size of 70 mm × 92.5 mm × 145 mm, low weight of 1.93 kg, high output torque of 742.2 Nm/531.09 Nm in two directions under 210 bar, high torque to weight ratio of 265.5 Nm/kg, low internal leakage of about 9 mL/min, zero external leakage, low starting pressure of 0.26 MPa/0.39 MPa in two directions, and a large rotation angle of 135 degrees. Compared with HyAs that have been applied in robot joints, the HyA proposed in this paper can greatly reduce the joint weight, reduce the joint size, and ensure the control performance of the joint movement.In addition, a dynamic model of the HyA is established. Based on this, some dynamic design suggestions are given. Furthermore, a simple position and torque control algorithm for the HyA is proposed. Finally, some experiments are carried out to verify the performance of the HyA.

Application of high-strength strain-hardening cementitious composites (SHCC) in the design of novel inter-module joint

The adoption of modular buildings has been promoted around the world in recent years, especially in densely populated areas such as Hong Kong that require a large number of new housing units to be quickly constructed. In modular construction, it is important to minimize the cast-in-place joints between prefabricated modules for a variety of reasons, including lowering the height of the building to reduce wind loads, as well as improving on-site construction efficiency. Combining the use of high-strength fiber-reinforced cementitious composites (HSFRCC) and steel plate confinement, the authors proposed a novel inter-module joint connection method and demonstrated that it can greatly enhance the bond strength and reduce joint size. In this study, the feasibility and effectiveness of using an alternative material – high-strength strain-hardening cementitious composites (SHCC) – is explored. Compared with HSFRCC, high-strength SHCC can attain similar compressive and tensile strengths while achieving considerably superior ductility. It also provides better capability in energy absorption and crack control. Tensile pull-out tests were performed to investigate the bond behavior between rebar and high-strength SHCC. It is reported that high-strength SHCC achieved enhanced bond performance compared to high-strength concrete, but the improvement was not as pronounced as HSFRCC. 3D models were built in a finite element program, and the simulations agreed well with test results. Parametric studies were conducted using the FE models to identify the main influencing factors of bond strength and to determine their relative importance. Design calculation methods were then developed to facilitate the engineering application of the novel joint connection.

Research on Parameter Design Method and Motion Characteristics of a Ball Cage Flexible Joint

The flexible joint is an important part in ultra-short-radius drilling tools, and its structural parameters and motion characteristics are key factors affecting the success of drilling. In this work, a new type of ball cage flexible joint, which is applied in 5″ and 5.5″ cased wells, was proposed based on the working principle of the ball cage universal joint. A structural parameter design method for the ball cage flexible joint was established according to the geometric coordination relation and material strength theory. Using this new method, the length, diameter, and window size of the ball cage flexible joint were analyzed. The multi-body motion process was further analyzed using a multi-body dynamics method, and then the motion characteristics, such as impact contact force, isokinetic characteristics, transfer efficiency, deflection torque and so on, were studied. Based on the above analyses, the structural parameters of the designed joint were optimized by means of the orthogonal test method. Results demonstrate that the experimental ball cage flexible joint has excellent isokinetic transmission characteristic, which can effectively suppress vibration and shock caused by changes in rotational speed. The transmission efficiency of the structure was 89.8%, while the power loss rate was 0.102%. According to the orthogonal test analysis, the optimal structure of the flexible joint has a ball seat diameter of 80 mm, a ball head diameter of 62 mm, and a ball key diameter of 16 mm. It is important to note that the ball key diameter was the most influential factor on the flexible joint internal contact force. The ball key contact force varied periodically, and there was a significant phase difference between the contact forces of different balls. On the other hand, with an increase in the flexible joint working angle, the deflection torque increased gradually, and the vibration amplitude of the torque increased. This work can provide reference for the parameter optimization design of the new flexible joint.

3D morphology reconstruction of rock joints from 2D profile measurement by a profilograph

Rock mass stability is closely related to the shear strength of rock joints. Measuring the joint surface morphology is of vital importance for evaluating the shear strength of rock joints. Although non-contact measurement methods such as laser scanning are advantageous in high precision, the characteristics of high purchase cost or rental fees and being susceptible to the operating environment have weakened their practicability for in-situ batch measurement of the three-dimensional (3D) morphology of joints. To facilitate the possibility of utilizing cost-effective contact-based devices to replace the non-contact ones, we proposed a methodology to reconstruct the 3D morphology of rock joints using two-dimensional (2D) joint profiles measured by contact measurement methods (e.g., a profilograph). First, through a comprehensive comparison of commonly used spatial interpolation methods, the V4 method from the Griddata function is determined as the optimal one for the proposed methodology. Then, based on the optimal spatial interpolation method, the appropriate profile interval is determined through a referential band derived in this study. Finally, the performance of the proposed methodology was validated from experimental and theoretical perspectives. Results show that the relative errors of the test cases are within the engineering permissible error range, and more than 92% of the test cases are associated with an error less than 5%. In addition, the influences of the joint mechanical parameters, joint roughness level, and joint size on the appropriate profile interval are investigated. This methodology offers a cost-effective alternative for in-situ batch measurement of joint 3D morphology in the field survey of rock joints.

COMPARISON OF EFFICACY OF INDOMETHACIN AND TIZANIDINE IN EXPERIMENTAL MODEL OF ARTHRITIS IN ALBINO WISTAR RATS

Background: Rheumatoid arthritis is an autoimmune disease primarily affecting small peripheral join. It is characterised by joint inammation and pain. There were 3 groups with 6 albino wistar rats in each. Each group was i Methods: njected with CFA in one of hind paw on a day before (day 0) treatment with Indomethacin (3mg/Kg), Tizanidine (1mg/Kg), & Tizanidine (2mg/Kg). Each drug was given PO in their respective group. Joint size was measured on day 0, 3, 7, 14, and 21. Difference in joint size with day 0 was calculated. Difference in joint size on different Results: days of measurement was minimum for indomethacin & maximum for tizanidine (1mg/Kg). Difference of joint size for tizanidine (2mg/Kg) was in between two. Data was analysed using one way ANOVA. There was no signicant difference between the groups. Tizanidine has an Conclusions: anti-inammatory property in CFA induced rheumatoid arthritis experimental model. This property of tizanidine was more at dose of 2 mg/ Kg as compared to 1 mg/Kg. As tizanidine has gastro-protective effect so it can be a promising treatment along with NSAIDs.

Study on dynamic behavior of tubular T-joints subjected to out-of-plane impact loading

In this study, the failure mode, impact resistance, and other key factors affecting the deformation of T-shaped circular steel tubular joints subjected to out-of-plane impacts are studied using a combination of numerical and analytical methods. The finite element (FE) analysis for circular hollow section (CHS) tubular T-joints subjected to in-plane impact is carried out. The simulation results are in good agreement with the test results, and the error is <6%. For common joint sizes in engineering, 63 FE models of CHS tubular T-joints subjected to out-of-plane impacts are created, and the deformation patterns and impact force development processes are described. In particular, following previous research into the deformation laws of steel tube structures, this study proposes a modified equal area axis method and utilizes it to distinguish the bending displacement and local indentation. Using the displacement changes and research results for T-joint failure modes, the criteria for judging the failure modes of the specimen are proposed, and the failure mode is categorized into three types. By discussing the influence of four parameters [length-to-diameter ratio of the chord (α), diameter ratio of the brace-to-chord (β), impact energy (Ek), and length-to-diameter ratio of the brace (αh)] upon the joint deformation of the specimen, a prediction formula for the global and local deformation of a T-shaped steel tube joint under out-of-plane impact loads with respect to the four abovementioned parameters is obtained via data fitting, and the accuracy of the formula is verified via error analysis.

Experimental Study on Bending Resistance of New Type Joint of Prestressed Concrete Pipe Pile

In the field of PHC pile joints, it is important that prestressed high-strength concrete pipe piles are referred to as PHC pipe piles. In conventional hoops, bamboo-like joints protrude from the pile joint position at the surface of the pile. Driving the pile in, disturbing the soil around the pile, and affecting the frictional resistance are serious issues. To address such issues, herein, a new type of clamping joint is proposed. A new method is presented to determine the size of the new joint that is flushed with the surface of the pile at the joint position. Bending resistance tests are conducted on four types of new joints for common pipe piles to study the deformation development process, bending bearing capacity, and damage characteristics of the new joints. Cracks are mainly distributed in the pure bending section and are approximately symmetrically distributed along both sides of the joint; there is no obvious cracking and damage in the joint until the pile cracks. Under the same bending moment, the deflection in the span of all specimens is greater than the deflection at the loading point.

Tail-stiffness optimization for a flexible robotic fish

Undulation regulation in a robotic fish propelled by a passive flexible tail is more similar to that of a natural fish than with a rigid tail, owing to the smooth curvature of the flexible tail. Moreover, it has been observed that fish change the stiffness of their bodies to adapt to various swimming states. Inspired by this, a stiffness optimization scheme is explored for a novel elastic tail, which can improve the performance of the robotic fish. Spring steels are used as passive flexible joints of the fishtail; these can be easily expanded into multi-joint structures and the joint stiffness can be altered by changing the joint size. In this study, the Lagrangian dynamic method is employed to establish a dynamic model of the robotic fish in which passive flexible joints are simplified by a pseudo-rigid-body model. In addition, the hydrodynamics of the head and tail are analyzed using the simplified Morison equation and quasi-steady wing theory, respectively. Furthermore, to determine unknown hydrodynamic parameters in the dynamic model, a parameter identification method is applied. The results show that the identified simulation speeds fit the experimental speeds well within a wide range of stiffness values. Finally, to improve performance, the influence of joint stiffness and frequency on swimming speed is investigated based on the identified dynamic model. At each frequency, the optimal joint stiffness distribution is one that reduces the stiffness from the front to the rear. At the maximum driving frequency of 2.5 Hz, the optimal swimming speed is 0.3 body lengths per second, higher than that when rigid joints are used.

Thermomechanical finite element modeling of steel ladle containing alumina spinel refractory lining

Refractory linings are used in steel ladles in iron and steel industry, to protect the vessel structure from the molten steel (with temperature above 1600 °C). To increase the durability of the refractory lining, researching the possible failure causes is of importance. In recent decades, alumina spinel refractories have become a common material in the barrel zone of steel ladles in direct contact with steel. In this regard, the current study employed unit-cell finite element modeling technique to investigate the irreversible material behavior of alumina spinel bricks. At first, a study on the joint size and friction effect was conducted. Then, three distinct constitutive material models were assigned to the working lining, each corresponding to an irreversible deformation mechanism. The Norton-Bailey creep model was used to simulate creep behavior, the Drucker-Prager yield criterion was used to simulate shear failure, and concrete damaged plasticity was used to describe tensile failure. The findings of the three models were compared to understand how each phenomenon affected the lining's and steel shell's stress-strain response. The simulations showed the occurrence location and time of each irreversible behavior. The effect of considering plasticity for the steel shell on the mechanical behavior of the refractory lining was also investigated, which showed a decrease of irreversible strains at the working lining. • Alumina spinel lining behavior in a steel ladle was simulated using Unit-cell modeling technique. • Creep, tensile failure, and shear failure influence different parts of the lining. • Creep, tensile failure, and shear failure occur at different points during the working cycle. • Shell plasticity has a considerable effect on the stress and strain results.

Research on irregular wear mechanism of planar multi-body mechanical system with multi-clearance joints

An approach for analyzing and quantifying the irregular wear effect of planar multi-body mechanical system with multi-clearances is proposed. The classical planar four-bar linkage is used as a demonstrative example to study the mechanism of irregular wear effect of multi-body system with multi-clearances. The system dynamic equation is established using Lagrange multiplier method, the contact force and friction in the process of contact collision are respectively modeled using the Lankarani-Nikravesh (L-N) nonlinear contact force and LuGre models, and the wear depth prediction model for multi-clearance joints is built based on Archard’s equation. The influence of the crank speed, clearance number, clearance position and clearance size on the wear effect of multi-clearances system is comprehensively studied. Numerical simulation results show that the wear depth joint increases with increase of crank speed, and there are significant differences in the wear depth of different clearance joints. When the clearance size changes, the significant nonlinear wear phenomenon appears at different joints, when the clearance size of different joints meets a certain proportion, the system wear phenomenon is the least. The obtained valuable results provide important theoretical support for the optimal design of multi-clearance joints system.