Joint Size Research Articles

Ultrasonic Welding Parameter Optimization for Electric Component Welding

Industrial requirements to establish metallic joints between dissimilar metals in the electric area. The ultrasonic welding process is an optimal process to joint thin sheets or foils. The goal of the research was to optimize the ultrasonic welding parameters to join thin nickel-coated copper sheets and aluminium sheets. It used a 0.5 mm thick high-purity copper (Cu-OF-R200) sheet coated with a 10 μm pure nickel layer and a 0.5 mm thick aluminium (1050A H24) sheet. The ultrasonic welding is made by a Branson Ultraweld L20 ultrasonic welder equipment. The mechanical properties and exacting geometrical tolerance of the joint were required. The welding parameter optimization is made empirically, with several welding tests. The optimal welding parameters were confirmed by non-destructive and destructive tests of the joints. The non-destructive tests were the visual inspection and geometrical measurements of the joint sizes. The destructive tests were tensile tests and macroscopic and microscopic tests. The completed test results confirmed the process applicability and the quality of the joint.

How Multifunctioning Joints Produce Highly Agile Limbs in Animals with Lessons for Robotics.

This paper reviews how multifunctioning joints produce highly agile limbs in animals with lessons for robotics. One of the key reasons why animals are so fast and agile is that they have multifunctioning joints in their limbs. The multifunctioning joints lead to a high degree of compactness which then leads to a host of benefits such as low mass, low moment of inertia and low drag. This paper presents three case studies of multifunctioning joints-the human wrist joint, knee joint and foot joints-in order to identify how multifunctioning is achieved and what lessons can be learned for robotics. It also reviews the multifunctioning nature of muscle which plays an important role in joint actuation. A key finding is that multifunctioning is achieved through various means: multiple degrees of freedom, multifunctioning parts, over-actuation and reconfiguration. In addition, multifunctioning is achieved through highly sophisticated layouts with high levels of integration and fine-tuning. Muscle also makes an important contribution to animal agility by performing multiple functions including providing shape, protection and heat. The paper reviews progress in achieving multifunctioning in robot joints particularly for the wrist, knee and foot. Whilst there has been some progress in creating multifunctioning robotic joints, there is still a large gap between the performance of animal and robotic joints. There is an opportunity to improve the agility of robots by using multifunctioning to reduce the size and mass of robotic joints.

Geometric modelling of corrosion inhibitor pigments in active protective coatings based on SR-nano-CT images

This paper reports on an essential step towards accelerating the development of new, environmentally friendly active protective coatings by structure optimization. The complex microstructure of the pigment particles within a coating have been observed non-destructively in 3D by nano-computed tomography using synchrotron radiation. For the first time, a stochastic geometry model is fitted based on spatial geometric features of the particles observed in the 3D images. The typical cell of a random Gibbs-Laguerre tessellation is used to model the particles' polyhedral shapes as well as the observed joint size and aspect ratio distributions.

Effect of joint behaviors on the load-carrying capacity of single-layer reticulated dome

The majority of previous studies have primarily focused on the impact of nodal deviation or joint’s strong axis bending stiffness of semi-rigid single-layer reticulated shell, ignoring the effect of other kinds of joint stiffness and its interaction with joint size and nodal deviation. Therefore, the single-layer reticulated dome considering all kinds of joint stiffness and joint size is established initially. Subsequently, a comprehensive investigation is conducted to analyze the effect of all types of joint stiffness of improved bolt-column (IBC) joints, as well as joint size and nodl deviation, on the load-carrying capacity of dome. Finally, the coupling effect among these factors on the mechanical performance of dome is also determined. The main conclusions obtained are presented as follows: (I) the axial stiffness of the IBC joint significantly influences the load-carrying capacity of single-layer reticulated dome, resulting in an average decline ratio of 27 %; however, the other types of joint stiffness have a negligible impact, with an average effect of only 1 %. Moreover, the limit load of the dome considering practical stiffness of IBC joint can achieve the 61 % of that of rigid dome; (II) rigidly joined domes with nodal deviations of S/300, S/600, S/900, S/1200 and S/1500 exhibit decline ratios of 0.57, 0.47, 0.41, 0.37 and 0.34, respectively, in load-carrying capacity compared to perfect domes. Moreover, when considering the coupling effect of joint stiffness, joint size and nodal deviation on the load-carrying capacity of the domes, these nodal deviations affect the capacity by 0.65, 0.57, 0.52, 0.49 and 0.46.

Microstructural analysis and mechanical characterization of dissimilar welds between nickel-based and steel-based superalloys post-cryogenic treatment using hotwire GTAW

This study explores the dissimilar welding of nickel superalloy 59 with Fe-Ni superalloy 904 L using the Gas Tungsten Arc Welding with Hot Wire technique (HW-GTAW). The HW-GTAW process produced defect-free weldments with complete penetration, as confirmed by macroscopic analysis. Microstructural analysis using FESEM and EDS revealed fine equiaxed and columnar dendrites in the fusion zone and identified a secondary phase enriched with chromium. XRD analysis supported the presence of predominant austenitic phases and indicated the formation of Cr23C6-type carbide. The grain size of the weld joint, determined using the Gaussian method and Scherer formula, was 44.53 nm, slightly smaller than base metals. Microhardness tests revealed values ranging from 226 ± 5 HV 10 to 243 ± 5 HV 10, with the highest values observed in the deep cryogenic treatment (DCT). The Mo in the ERNiCrMo-13 filler and the effects of DCT, which promote grain refinement, are responsible for this increase in hardness. Residual stress measurements revealed a maximum tensile stress of 315 MPa along the longitudinal axis and a maximum compressive stress of 355 MPa along the transverse axis. DCT enhanced the weldment’s tensile strength by up to 12% compared to as-welded samples, with a 6% increase compared to shallow cryogenic-treated (SCT) samples. Charpy impact testing indicated a value of 88 J in the fusion zone, which is 1.2% less than alloy 59 and 9% higher than 904 L. Tensile fracture analysis revealed ductile dimples, while impact fractography showed a mix of ductile dimples and brittle, glassy cleavage facets.

Geometric Design Methodology for Deployable Self-Locking Semicylindrical Structures

Due to their unique bistable characteristics, deployable self-locking structures are suitable for many engineering fields. Without changing the geometrical composition, such structures can be unfolded and locked solely by the elastic deformation of materials. However, their further applications are hampered by the lack of simple and systematic geometric design methodologies that consider arbitrary structural curvature profiles. This paper proposes such a methodology for double-layer semicylindrical grid structures to simplify their cumbersome geometric design. The proposed methodology takes joint sizes into account to ensure that the design results can be applied to actual projects without further adjustments. By introducing symmetry into the structural units (SUs) and selecting reasonable geometric parameters that describe the structural side elevation profile, a concise set of simultaneous nonlinear geometric constraint equations is established, the solution of which provides the geometric parameter values of the grid shape. On this basis, the remaining geometric parameter values, i.e., the geometric parameter values of the inner scissor-like elements (SLEs) of each SU, can be achieved from the equations derived from general SLEs. Design examples and the assembled physical grid structure indicate the feasibility and wide applicability of the proposed geometric design methodology.

Predicting the failure of rock using critical slowing down theory on acoustic emission characteristics

The joint surfaces and size affect the mechanical behavior and failure precursors of shale. Therefore, this paper studies the mechanical behavior, the response characteristics of acoustic emission (AE) and critical slowing down (CSD) characteristics of AE for shale with different joint surfaces and size. The results show that with an increase in the number of joint surfaces and the size of the sample, the crack initiation stress, uniaxial compressive strength (UCS), peak strain, and fractal dimension decrease. During the plastic stage, the occurrence of a sharp rise in AE ringing count, RA, a low-frequency, high-amplitude AE signal, and a rapid drop in AF can be characteristics of impending sample failure. Variance and autocorrelation coefficients can be used to characterize the CSD phenomenon. The optimal window length and lag step are determined to be 400 and 100, respectively. The CSD characteristics of the autocorrelation coefficient and the variance of multi-AE parameters are obtained. The variance-based early warning time provides short-term early warning, while the autocorrelation coefficient-based early warning time provides early warning. The research results can provide theoretical references for the mechanical design and failure prediction of underground rock engineering.

Having More Tender Than Swollen Joints Is Associated With Worse Patient-Reported Outcomes in Patients With Early RA.

In patients with rheumatoid arthritis (RA), high tender-swollen joint differences (TSJDs) have been associated with worse outcomes. A better understanding of the phenotype and impact of high TSJD on patient-reported outcomes (PROs) in early RA may lead to earlier personalized treatment targeting domains that are important to patients today. Our objectives were to evaluate the impact of TSJD on updated PROs in patients with early RA over 1 year and to determine differences in associations by joint size. This longitudinal cohort study followed patients with active, early RA enrolled in the Canadian Early Arthritis Cohort between 2016 and 2022, who completed clinical assessments and PROMIS-29 measures over 1 year. Twenty-eight joint counts were performed and TSJDs calculated. Adjusted associations between TSJD and PROMIS-29 scores were estimated using separate linear-mixed models. Separate analyses of large versus small-joint TJSDs were performed. Patients with early RA (n = 547; 70% female; mean [SD] age, 56 [15] years; mean [SD] symptom duration, 5.3 [2.9] months) were evaluated. A 1-point increase in TSJD was significantly associated with worse PROMIS T-scores in all domains: physical function (adjusted regression coefficient, -0.27; 95% confidence interval [CI], -0.39, -0.15), social participation (adjusted regression coefficient, -0.34; 95% CI, -0.50, -0.19), pain interference (adjusted regression coefficient, 0.49; 95% CI, 0.35, 0.64), sleep problems (adjusted regression coefficient, 0.29; 95% CI, 0.16, 0.43), fatigue (adjusted regression coefficient, 0.34; 95% CI, 0.18, 0.50), anxiety (adjusted regression coefficient, 0.23; 95% CI, 0.08, 0.38), and depression (adjusted regression coefficient, 0.20; 95% CI, 0.06, 0.35). Large-joint TSJD was associated with markedly worse PROs compared with small-joint TSJD. Elevated TSJD is associated with worse PROs particularly pain interference, social participation, and fatigue. Patients with more tender than swollen joints, especially large joints, may benefit from earlier, targeted therapeutic interventions.

Asymmetry in linear measurements and cross-sectional geometry in the humerus during ontogeny.

Adult upper limb asymmetry is used to reconstruct behavior. However, the developmental trajectory of asymmetry in bone length, cross-sectional geometry (CSG), and joint dimensions is poorly understood. This study examines the development trajectory of humeral asymmetry and if asymmetry in bone length, joint size, and CSG develop in concert. Linear measurements of bone length and metaphyseal/epiphyseal breadth, bending rigidity (Imax and Imin), and cross-sectional shape (Imax/Imin) at 30%, 50%, and 70% of bone length were acquired from 3D models of humeri from four skeletal samples of prehistoric hunter-gatherer populations (n = 82). Dental age cohorts were used to assess ontogenetic trends. Percent absolute (%AA) and directional (%DA) asymmetry were calculated for paired measures. Percentage of matching direction of asymmetry across variables and correlation analysis tested relationships between variables. Within the total pooled sample, Imax shows the highest %AA and %DA, followed by shape and linear dimensions. Asymmetry is lowest in neonates and increases with age, particularly %DA of Imax in mid-proximal sections. Correlations among variables are low to moderate and strongest between Imax measures. Matching direction of asymmetry between variables is low and generally increases with age. Higher correlations with age in CSG likely indicate greater responsiveness to mechanical loading. Low correlations in magnitude of asymmetry and side dominance suggest independence in the development of asymmetry between maximum rigidity, shape, and linear measures. Differences in how asymmetric loading affects the ontogeny of linear and CSG variables may account for the heterogeneous development of asymmetry.

Joint Sizing Optimization Method of PVs, Hybrid Energy Storage Systems, and Power Flow Controllers for Flexible Traction Substations in Electric Railways

Joint Sizing Optimization Method of PVs, Hybrid Energy Storage Systems, and Power Flow Controllers for Flexible Traction Substations in Electric Railways

Determining the optimal sampling interval for 3D morphology measurements of different-sized natural rock joints

Efficiently studying the scale effect of surface roughness and peak shear strength of natural rock joints, especially unfilled and well-matched ones, requires an optimal sampling interval to realize cost-effective three-dimensional morphology measurements for different-sized natural rock joints with advanced non-contact optical devices. However, rationally determining such an optimal sampling interval remains controversial. To this end, inspired by digital signal processing, the optimal sampling interval is creatively determined by Shannon's sampling theorem using the Fourier series' optimum order. An empirical formula relating the joint size to the optimum order is correspondingly developed. The proposed empirical formula was found to work well under conditions of high normal stress, where the relative errors for the surface roughness and peak shear strength of series-sized natural rock joints were mostly less than 10% and 5%, respectively, but should be used cautiously under conditions of low normal stress. Furthermore, different from previous perceptions, a higher joint roughness level was discovered to not necessarily imply the need for a smaller optimal sampling interval, and conversely. The proposed empirical formula can facilitate the determination of the optimal sampling interval for measuring different-sized natural rock joints' surface morphologies in engineering practice.

Effect of elastic deformation on lubrication characteristics in different clearances and head size of metallic artificial hip joint

The issue of lubrication in metallic artificial hip joints is discussed to prevent the two bearing surfaces from contacting each other. This study aims to analyse the characteristics of elastohydrodynamic lubrication (EHL) and investigate the effect of radial clearance and head size on the tribological performance of metallic artificial hip joints under steady-state conditions using the Fluid-Structure-Interaction (FSI) method. The average load in the z-direction and flexion-extension motion around the y-axis were used to represent normal walking. This study demonstrates that the film thickness profile from the validation study aligns with the findings of the previous study. The contour of the fluid pressure in the central contact zone changes with different time steps – the direction of fluid movement corresponds to the solid-fluid reaction. Additionally, the deformation of the cup surfaces contributes to the continuous fluid film that separates the contact surfaces. Furthermore, design parameters also influence EHL performance. It has been discovered that less radial clearance and a larger head size led to an increase in fluid film thickness.

Having More Tender Than Swollen Joints is Associated With Worse Function and Work Impairment in Patients With Early Rheumatoid Arthritis.

Patients with early rheumatoid arthritis (RA) may present with more tender than swollen joints, which can persist. Elevated tender-swollen joint difference (TSJD) is often challenging, because there may be multiple causes and it may contribute to overestimating disease activity. Little is known about the phenotype and impact of TSJDs on patient function. Our objective was to evaluate the impact of TSJD on functional outcomes in early RA and to see whether associations vary by joint size. Data were from patients with active, early RA (≤12 months) enrolled in the Canadian Early Arthritis Cohort, who completed assessments of general function (Multidimensional Health Assessment Questionnaire [MDHAQ]), upper extremity (UE) function (Quality of Life in Neurological Disorders [Neuro-QoL] UE scale), and work/activity impairment (Work Productivity and Activity Impairment RA) over their first year of follow-up. A total of 28 joint counts were performed. TSJDs were calculated. Adjusted associations between TSJDs and functional outcomes were estimated in separate multivariable linear mixed effects models. Separate analyses were performed for large- versus small-joint TSJD. Patients (N=547) were 70% female, mean age 56 (SD 15) years, mean disease duration 5.3 (SD 2.9) months. At baseline, 287 (52%) had TSJD >0 (43% involved large joints and 34% small joints), decreasing to 32% at 12 months. A one-point increase in TSJD was significantly associated with worse function (MDHAQ: adjusted mean change 0.10, 95% confidence interval [CI] 0.08-0.13; Neuro-QoL UE function T score: adjusted mean change -0.59, 95% CI -0.76 to -0.43; and greater work impairment: adjusted mean change 1.95%, 95% CI 0.85%-3.05%). Higher large-joint TSJDs were associated with the worst functional outcomes. Having more tender than swollen joints is common in early RA and is associated with worse function, most notably when involving large joints. Early identification and targeted intervention strategies may be needed.

Optimizing the Mechanical Properties of the Weld in the Friction Stir Welding of Aluminum and Magnesium (A365–AZ91C)

The friction stir welding of A365 and AZ91C alloys was conducted in this study to assess the effect of tilt angle, linear velocity and rotating speed on the elongation, hardness and tensile strength using the response surface method. Then, the weld microstructure was investigated by SEM, TEM and EDS analysis to deeply investigate the structure of A365–AZ91C weld. It was realized that the grain size of weld joint has grown and the crack and tunnel were formed when the rotating speed improved from 1000 to 2000[Formula: see text]rpm, which produced a decline in the hardness and strength and a rise in the elongation. Moreover, an increment of linear velocity up to 60[Formula: see text]mm/min led to the refinement of the weld microstructure, which was followed by an enhancement in the strength and hardness of the weld, whereas the elongation deteriorated. In the case of tilt angle, the highest elongation and strength were detected at a tilt angle of 2∘, but the highest hardness was observed at a tilt angle of 4∘ because of the nucleation of Al3Mg2 and Al[Formula: see text]Mg[Formula: see text] intermetallics. Results of optimization exhibited that the concurrent improvement of the strength, hardness and elongation can be acquired with the tilt angle of 3∘, rotating speed of 1600[Formula: see text]rpm and linear velocity of 53[Formula: see text]mm/min.

N2FXm, a method for joint nuclear and cytoplasmic volume measurements, unravels the osmo-mechanical regulation of nuclear volume in mammalian cells

In eukaryotes, cytoplasmic and nuclear volumes are tightly regulated to ensure proper cell homeostasis. However, current methods to measure cytoplasmic and nuclear volumes, including confocal 3D reconstruction, have limitations, such as relying on two-dimensional projections or poor vertical resolution. Here, to overcome these limitations, we describe a method, N2FXm, to jointly measure cytoplasmic and nuclear volumes in single cultured adhering human cells, in real time, and across cell cycles. We find that this method accurately provides joint size over dynamic measurements and at different time resolutions. Moreover, by combining several experimental perturbations and analyzing a mathematical model including osmotic effects and tension, we show that N2FXm can give relevant insights on how mechanical forces exerted by the cytoskeleton on the nuclear envelope can affect the growth of nucleus volume by biasing nuclear import. Our method, by allowing for accurate joint nuclear and cytoplasmic volume dynamic measurements at different time resolutions, highlights the non-constancy of the nucleus/cytoplasm ratio along the cell cycle.

Microstructure – Properties relationship in laser-welded AZ31B magnesium alloy

The AZ31B magnesium alloy was laser-welded at three different (1.2, 1.6, and 2 kW) laser output powers in the present work. All the butt weld joints are almost defect-free. The size of the weld joint slightly increases with increasing laser output power. The weld metal is formed by columnar grains of the alpha phase at the weld metal/base metal interface, but a finely equiaxed grain microstructure is formed in the centres of fusion zones. The minor phases are Mg17Al12 and (Al,Mg)8Mn5. The weld metal microstructure manifests clear refinement with a decrease in laser output power. Microstructural changes are reflected in changes in mechanical properties; weld joints prepared at the lowest laser output power manifest the highest microhardness, ultimate tensile strength, yield strength, and almost 90% joint efficiency. This is related to the different extents of strengthening mechanisms that act most effectively in weld joints made at 1.2 kW laser output power. Detail analysis of fracture surfaces confirmed that lower laser output power and general microstructural refinement favours the formation of plastically deformed material, which is in excellent agreement with both the experimentally determined and the calculated values of yield strength.

"Could a subset of joint mobility tests define generalized joint hypermobility?": A descriptive observational inception study.

Generalized joint hypermobility is an inherited collagen phenotype based on clinical assessments of joint mobility. However, there is no international consensus to define generalized joint hypermobility, both considering which joint mobility tests should be included and limits for joint hypermobility. The primary aim of the study was to identify a subset of joint mobility tests to define generalized joint hypermobility. A further aim was to evaluate standardized limits for the classification of hypermobility in different joint types throughout the body. A total of 255 early pregnant women were included in the study. Joint mobility was measured according to a structured protocol. Correlation and principal component analysis were used to find a subset of joint mobility tests. To classify hypermobility in each joint mobility test, five different standard deviation levels plus 0.84, plus 1.04, plus 1.28, plus 1.64 and plus 2 were used, corresponding to 20%, 15%, 10%, 5% and 2.5% of the normal distribution. No subset of joint mobility test could define generalized joint hypermobility. The higher the standard deviation levels, the higher the limit to classify joint hypermobility and the lower the prevalence. As a result of no subset of joint mobility tests were found to define generalized joint hypermobility, different combinations of major and minor joints in upper and lower limbs and the axial skeleton, were systematically developed. These combinations were evaluated for each standard deviation level, resulting in a prevalence of generalized joint hypermobility between 0% and 12.9% and a clear variation in how the hypermobile joint mobility tests were distributed. It is probably not possible to choose a subset of joint mobility tests to define GJH. In order not to overlook generalized joint hypermobility, a broader assessment of different joint types and sizes of joints appears to be needed. The prevalence of generalized joint hypermobility is dependent on joint hypermobility limit and the chosen combination of joint mobility tests.

Influence on the roof stability of EMU induced by welding deformation

The EMU roof with a thin plate structure is prone to buckling deformation during welding, which will affect its stability. Due to the complex structure, large size, and many types of welded joints, it is an urgent problem to solve the influence of different joint shapes on welding deformation and buckling stability in one model. Based on the inherent strain-temperature loading method, the inherent strain data of four kinds of local joint butt, lap, fillet, and plug welding were accurately obtained through joint welding deformation verification. Then the welding deformation simulation and buckling stability analysis were conducted. The results indicate that plug welding will have minimal impact on roof deformation. The roof buckling deformation cannot occur under the original and 1.2 times heat input conditions are selected within the range of the actual given heat source parameters. Under the 1.5 times heat input condition, the roof buckling deformation occurs. The results provide technical support for the selection of the welding process and the roof stability study of the EMU.

Finite Element Analysis of Joint in Prefabricated Carbon Fiber Composite Truss

Carbon fiber composite truss, as an innovative structural form, has been widely used in the construction industry. However, the joint is serving as a crucial component of the truss structure construction. In order to improve the design level of the truss, this paper mainly studies the prefabricated carbon fiber composite truss joints. Firstly, the finite element analysis method is used to simulate the truss joint, and the stress nephogram under different geometric conditions is obtained. Then, the stress deformation mode and stress distribution mode are analyzed in depth. The calculation results are compared with similar steel pipe truss joints, and the accuracy of stress distribution is verified. Finally, the relationship between stress concentration area, stress concentration degree, maximum stress size and geometrical parameters of joint is revealed. Results in this paper can guide the design of this kind of truss structures, which can help develop more efficient and durable construction projects

An Enhanced Circumferential Winkler Contact Force Model for Cylindrical Clearance Joints

In deployable space structures, the clearance size of joints is small, and the contact between the journal and bearing should sometimes be treated as a conformal contact, resulting in the imprecision of the contact force models in evaluating contact forces. This study proposes an enhanced hybrid theoretical and numerical contact force model to calculate the clearance joints’ contact force. Firstly, a basic formula of a dimensionless contact force is proposed, and an optimized surrogate function of the shape correction coefficient is obtained using finite element method (FEM) and response surface method (RSM). Then, the proposed model is validated by comparing it with various contact force models. Finally, this paper discussed the applicability of the proposed model in detail. These results indicate that the dimensionless expression of the proposed model is reasonable and can reasonably describe the relationship between contact force and penetration depth. The proposed model has been proven to have an excellent correlation with FEM and a minor relative error. The application scope of the proposed model is unlimited to the clearance size and the joint size. The proposed model provides a foundation for accurate impact models and is vital for the structural dynamic problems of high-precision space structures.