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1
Özes, Çiçek, e Özgen Aydin. "Analysis of Sandwich T-Joints under Compression Loads in Marine Applications". Advanced Composites Letters 18, n. 3 (maggio 2009): 096369350901800. http://dx.doi.org/10.1177/096369350901800301.
Testo completoAbstract (sommario):
This paper deals with the analysis of sandwich T-joints in terms of buckling loads, which are used in marine applications. Buckling loads have been investigated experimentally and numerically. Loading is applied as uniform axial compression. The GRP/PVC sandwich composite T- joints have been manufactured in six different geometries. Numerical and experimental results both show that the geometry of the T-joint area affects the buckling loads. It has been observed that failure mode is the same in all of the joint types, which is core shear. Stress distributions in T-joints have also been investigated under buckling loads and also for a constant compression load. It is seen that T-joint geometry has an effect on stress distributions obtained under buckling loads.
2
Kipp, Kristof, Josh Redden, Michelle Sabick e Chad Harris. "Kinematic and Kinetic Synergies of the Lower Extremities During the Pull in Olympic Weightlifting". Journal of Applied Biomechanics 28, n. 3 (luglio 2012): 271–78. http://dx.doi.org/10.1123/jab.28.3.271.
Testo completoAbstract (sommario):
The purpose of this study was to identify multijoint lower extremity kinematic and kinetic synergies in weight-lifting and compare these synergies between joints and across different external loads. Subjects completed sets of the clean exercise at loads equal to 65, 75, and 85% of their estimated 1-RM. Functional data analysis was used to extract principal component functions (PCF’s) for hip, knee, and ankle joint angles and moments of force during the pull phase of the clean at all loads. The PCF scores were then compared between joints and across loads to determine how much of each PCF was present at each joint and how it differed across loads. The analyses extracted two kinematic and four kinetic PCF’s. The statistical comparisons indicated that all kinematic and two of the four kinetic PCF’s did not differ across load, but scaled according to joint function. The PCF’s captured a set of joint- and load-specific synergies that quantified biomechanical function of the lower extremity during Olympic weightlifting and revealed important technical characteristics that should be considered in sports training and future research.
3
Zhuang, Fujian, e Puhui Chen. "Effects of missing fasteners on the mechanical behavior of double-lap, multi-row composite bolted joints". Journal of Composite Materials 52, n. 28 (2 maggio 2018): 3919–33. http://dx.doi.org/10.1177/0021998318771464.
Testo completoAbstract (sommario):
This paper presents a numerical investigation into the effects of missing fasteners on the mechanical characteristics of double-lap, multi-row composite bolted joints. A highly efficient explicit finite element model, which was validated effective and accurate by experiments, was developed and employed to conduct the virtual tests. Single-column and multi-column joints with various positions of missing fastener were considered. It is shown that the removal of fasteners can reduce the joint stiffness significantly, especially in joints with fewer columns or missing fasteners in the outside rows. The removal of fasteners can also cause considerable reductions in both the initial significant failure loads and ultimate loads of multi-column joints, while in single-column joints only the initial significant failure loads are influenced. Considering the load distribution, it is suggested that bolts in the same column as or in the adjacent column to the missing fastener experience a notable growth in load. Meanwhile, if a bolt bears more loads in the pristine joint, the larger changes in stiffness, ultimate strength, and load distribution may be obtained when it is lost.
4
Grosse, I. R., e L. D. Mitchell. "Nonlinear Axial Stiffness Characteristics of Axisymmetric Bolted Joints". Journal of Mechanical Design 112, n. 3 (1 settembre 1990): 442–49. http://dx.doi.org/10.1115/1.2912628.
Testo completoAbstract (sommario):
A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to the bolt stiffness during large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. A number of sensitivity studies were carried out to assess the effect of various parameters on the axial joint stiffness. The results revealed that bending and rotation of the joint members, interfacial friction, and the bolt/nut threading significantly influence the axial stiffness characteristics of the bolted joint. The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.
5
Ooi, E. P., R. Daud, N. A. M. Amin e T. W. Hong. "Recent Development on Fracture Analysis of Solder Joints". Applied Mechanics and Materials 695 (novembre 2014): 680–83. http://dx.doi.org/10.4028/www.scientific.net/amm.695.680.
Testo completoAbstract (sommario):
Solder joints failure due to thermal loads and mechanical loads is a significant reliability concern in electronic devices. From literatures, little attention is paid to the development of methods on predicting fracture behavior of solder joint under mixed-mode loading. In reality, the solder joints are exposed to drop impact, vibration loading, bending, and twisting of PCBs. Study on this matter will lead to prediction of fracture load, prevalent fracture mode, exact joint interconnect size and life of joints under brittle and fatigue failure. This paper presents a review of recent fracture analysis on solder joints.
6
Martin, Heiner, Michael Stiehm, Ingmar Rinas, Niels Grabow e Thomas Mittlmeier. "Testing of dynamic wrist joint external fixator mobility and reaction moment". Current Directions in Biomedical Engineering 4, n. 1 (1 settembre 2018): 447–48. http://dx.doi.org/10.1515/cdbme-2018-0106.
Testo completoAbstract (sommario):
AbstractFor the investigation of reaction moments of wrist joint with external fixator, a test device was developed that allows a well-defined investigation of the joint loads during hand flexion movements. The reaction moments are considered as a measure for the joint loads due to the constraint forces, which occur with differences of the rotation axis of the fixator device from the physiological rotation axis of the wrist joint. The developed test device allows a dynamic momentum load application into the wrist by a servohydraulic testing machine. This testing device converts the force to a moment by a constant lever arm and allows thereby the measurement of the reaction moments by the force load cell of the testing machine. Measurements on cadaveric wrist joints with external fixator can be thereby performed under reproducible conditions. The cadaveric wrist joints can be integrally casted into bone cement and thereby clamped to the testing device. Preliminary experiments with artificial bones showed that forces within the measuring range of the load cell of the testing machine can be measured. The design of the test device is presented. Hence, the requirements for measurements of the reaction moments with wrists with external fixator for distal radius fractures under dynamic loads are created.
7
Malhotra, S. K., e B. Thomas. "Effect of interface gap on load–slip characteristics of timber joints fabricated with multiple nails". Canadian Journal of Civil Engineering 12, n. 1 (1 marzo 1985): 104–13. http://dx.doi.org/10.1139/l85-011.
Testo completoAbstract (sommario):
An experimental program, exploratory in nature, has been carried out to investigate the effect of interface gap on the load–slip behaviour of joints fabricated with multiple nails. In total, 320 joint specimens have been tested. Modification factors are developed to account for the effects of number of nails and interface gap on the overall load-carrying capacity of joints with multiple nails. The current practice for the design of nailed joints is that a joint fastened together with multiple nails in a row, regardless of the interface characteristics of that joint, carries lateral load equal to the product of the lateral-load capacity of the corresponding joint with a single nail and the number of nails in a row of the joint. The findings of this investigation indicate this practice to be somewhat of an overestimation of the overall capacity of the joint. Key words: design, interface gap, interface friction, joint slip, loads (forces), modification factors, multiple fasteners, nailed joints, stiffness, structural engineering, tests, timber construction.
8
Chen, Yu Li, Kang Kang Wang e Xiao Xiao Zhang. "Effect of Load Direction on Failure of Out-of-Plane Composite Joints". Advanced Materials Research 1095 (marzo 2015): 934–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1095.934.
Testo completoAbstract (sommario):
The mechanical properties of fabric composite π joints under stretch-bending load are studied using the progressive damage method. The failure mode of fillers is evaluated by the modified maximum stress failure criterion due to their structural particularity, while other parts of the joint by the maximum stress failure criterion. Compared with the results of joints under simple tensile load, the numerical simulation result of the joint under stretch-bending loads with varied directions reveals that the flexion can cause significant reduction in the initial and ultimate failure strength although it has little effect on the structure stiffness before initial failure. In addition, the base laminate and the skin are more easily damaged under stretch-bending loads.
9
Ma, Yan Yan, Kai Fu Zhang, Zhao Jun Yang e Yuan Li. "Effects of Impact on the Failure of CFRP/Al Bonded Single-Lap Joints with Different Overlap Length". Advanced Materials Research 181-182 (gennaio 2011): 814–19. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.814.
Testo completoAbstract (sommario):
A parametric study on CFRP/Al adhesively bonded single lap joints was experimentally conducted. The primary objective of this study is to investigate the effects of overlap length and impact loads on the failure mode and failure load of joints. Experimental results show that structural failure of joints occurred in the adhesive layer or the bonded interface; failure loads and impact resistance of the joint increased as the overlap length increased; the carrying load of joints which subjected to impact declined significantly because of internal damage of the adhesive layer.
10
Pegado, Helio de Assis, Rafael Felipe De Souza e Rodrigo de Sa´ Martins. "Allowable Load Assessment in Metal-Composite Double-Lap Joint / Avaliação de Carga Permitida em Junta de Dupla Folga Metal-Composto". Brazilian Journal of Development 7, n. 8 (18 agosto 2021): 82563–75. http://dx.doi.org/10.34117/bjdv7n8-456.
Testo completoAbstract (sommario):
This work consists of evaluating the tensile and compression static allowable stress of a hybrid (metal-composite) riveted joint. The analyzed joint is composed by two sheets of 2014 – T6 aluminium alloy and a T300/5208 Graphite/Epoxy quasi-isotropic laminate, which were joined by twelve Lockbolt Swaged Collar rivets titanium alloy Ti–6Al–4V annealed. The joint was analyzed through a computational model developed using the Finite Element Method (FEM), with the fasteners modelled through the Multi - Springs technique. This method was widely used to simulate the mechanical behaviour metal-metal and composite-composite parts of the joint. It is validated comparing its results with analytical results of metallic joints available in the literature. Through this model, both the allowable load and its distribution in the fasteners of the joint were determined. Since the evaluated joint is subjected to double shear and, therefore, has no eccentricities, the presence of secondary bending was not observed, the bearing and bypass loads were the most relevant in evaluating the allowable loads of the joint. The load distribution in the joint and its components’ safety margin was determined, with the laminate being the limiting component of the allowable load.
11
Debicki, D. B., e P. L. Gribble. "Inter-Joint Coupling Strategy During Adaptation to Novel Viscous Loads in Human Arm Movement". Journal of Neurophysiology 92, n. 2 (agosto 2004): 754–65. http://dx.doi.org/10.1152/jn.00119.2004.
Testo completoAbstract (sommario):
When arm movements are perturbed by a load, how does the nervous system adjust control signals to reduce error? While it has been shown that the nervous system is capable of compensating for the effects of limb dynamics and external forces, the strategies used to adapt to novel loads are not well understood. We used a robotic exoskeleton [kinesiological instrument for normal and altered reaching movements (KINARM)] to apply novel loads to the arm during single-joint elbow flexions in the horizontal plane (shoulder rotation was allowed). Loads varied in magnitude with the instantaneous velocity of elbow flexion, and were applied to the shoulder in experiment 1 (interaction loads) and the elbow in experiment 2 (direct loads). Initial exposure to both interaction and direct loads resulted in perturbations at both joints, even though the load was applied to only a single joint. Subjects tended to correct for the kinematics of the elbow joint while perturbations at the shoulder persisted. Electromyograms (EMGs) and computed muscle torque showed that subjects modified muscle activity at the elbow to reduce elbow positional deviations. Shoulder muscle activity was also modified; however, these changes were always in the same direction as those at the elbow. Current models of motor control based on inverse-dynamics calculations and force-control, as well as models based on positional control, predict an uncoupling of shoulder and elbow muscle torques for adaptation to these loads. In contrast, subjects in this study adopted a simple strategy of modulating the natural coupling that exists between elbow and shoulder muscle torque during single-joint elbow movements.
12
Pickles, D. M., e C. R. Bellenger. "Load-Bearing in the Ovine Medial Tibial Condyle: Effect of Meniscectomy". Veterinary and Comparative Orthopaedics and Traumatology 06, n. 02 (1993): 100–104. http://dx.doi.org/10.1055/s-0038-1633027.
Testo completoAbstract (sommario):
SummaryTotal removal of a knee joint meniscus is followed by osteoarthritis in many mammalian species. Altered load-bearing has been observed in the human knee following meniscectomy but less is known about biochemical effects of meniscectomy in other species. Using pressure sensitive paper in sheep knee (stifle) joints it was found that, for comparable loads, the load-bearing area on the medial tibial condyle was significantly reduced following medial meniscectomy. Also, for loads of between 50 N and 500 N applied to the whole joint, the slope of the regression of contact area against load was much smaller. Following medial meniscectomy, the ability to increase contact area as load increased was markedly reduced.The load bearing area on the medial tibial condyle was reduced following meniscectomy.
13
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.
14
Karduna, A. R., G. R. Williams, J. P. Iannotti e J. L. Williams. "Total Shoulder Arthroplasty Biomechanics: A Study of the Forces and Strains at the Glenoid Component". Journal of Biomechanical Engineering 120, n. 1 (1 febbraio 1998): 92–99. http://dx.doi.org/10.1115/1.2834312.
Testo completoAbstract (sommario):
The objective of this study was to examine how changes in glenohumeral joint conformity and loading patterns affected the forces and strains developed at the glenoid. After removal of soft tissue (muscles, ligaments, and labrum), force-displacement data were collected for both natural and prosthetically reconstructed joints. Joints were shown to develop higher forces for a given translation as joint conformity increased. A rigid body model of joint contact forces was used to determined the so-called effective radial mismatch of each joint. For the purposes of this study, the effective radial mismatch is defined as the mismatch required for a rigid body joint to have the same force-displacement relationship as the joint in question. This parameter is an indication of the deformation at the articular surface. The effective radial mismatch dramatically increased with increasing medial loads, indicating that under physiological loads, the effective radial mismatch of a joint is much greater than its measured mismatch at no load. This increase in effective mismatch as medial loads were increased was found to be threefold greater in cartilaginous joints than in reconstructed joints. Rosette strain gages positioned at the midlevel of the glenoid keel in the reconstructed joints revealed that anterior/posterior component loading leads to fully reversible cyclic keel strains. The highest compressive strains occurred with the head centered in the glenoid, and were larger for nonconforming joints (ε = 0.23 percent). These strains became tensile just before rim loading and were greater for conforming joints (ε = 0.15 percent). Although recorded peak strains are below the yield point for polyethylene, the fully reversed cyclic loading of the component in this fashion may ultimately lead to component toggling and implant failure.
15
Gao, Deng Li, Zhen Bao Li, Guo Feng Wang e Jian Cheng Li. "The Experimental Investigation of Slab Participation in Flexural Behavior of Beams under Two-Way Loading". Applied Mechanics and Materials 105-107 (settembre 2011): 969–75. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.969.
Testo completoAbstract (sommario):
The paper designed three joints namely beam-column joint of reinforced concrete frame without slab and two beam-column joints of reinforced concrete frame with slab, using different loading methods (one direction and two directions) to experiment. The paper studied failure behavior, load-carrying capacity, and slab participation in flexural behavior of beam under different loading modes. Experiment shows that for the joints with slab, flexural capacity at end of the beam under two direction loads than one direction loads lows by about 10%; under one direction load, effective flange width of slab should be taken 8 times thickness, under two direction loads, effective flange width of slab should be taken 10 times thickness.
16
Padmanabhan, K. K., e A. S. R. Murty. "Damping in Structural Joints Subjected to Tangential Loads". Proceedings of the Institution of Mechanical Engineers, Part C: Mechanical Engineering Science 205, n. 2 (marzo 1991): 121–29. http://dx.doi.org/10.1243/pime_proc_1991_205_099_02.
Testo completoAbstract (sommario):
Metallic mating surfaces in machine joints offer an excellent source of energy dissipation, resulting in damped dynamic structural response, for example in machine tools. This paper describes the results of a series of experiments where the energy loss per cycle occurring at preloaded flat metallic interfaces subjected to cyclic tangential forces are measured. The effects of certain pertinent joint variables on the joint damping effectiveness are investigated. The results should be useful to the designers of machine tool structures, where damping occurring in joints is important.
17
Chen, Gongfa, Zhuangcheng Fang, Shaodi Wang, Haibo Jiang e Hualian Liang. "Numerical Analysis on Shear Behavior of Joints under Low Confining and Eccentric Loads". Advances in Civil Engineering 2019 (30 aprile 2019): 1–16. http://dx.doi.org/10.1155/2019/4589824.
Testo completoAbstract (sommario):
The joints of precast concrete segmental beams (PCSBs), which are in complex stress status and susceptible to failure, are very important parts of the structure. In this paper, a finite element model was established to study the shear performance of single-keyed joints. The plastic damage model was used to simulate the cracking of specimens. Three types of single-keyed joints were investigated, including the dry joint with normal concrete (NC), dry joint with steel fiber-reinforced concrete (SFRC), and epoxied joint with NC. The cracking pattern, ultimate shear strength, and load-displacement curve for these specimens were obtained. Based on these numerical simulation models, extended analyses in terms of low confining pressures and eccentric loads were performed. It has been found that the influence of fiber-reinforced concrete should be considered. The ultimate shear strength of specimens reduced with the reduction of confining pressure. When an eccentric load was applied, a lower shear capacity would be obtained. Under the low confining stress, the AASHTO LRFD 2014 provision underestimated the shear strength of single-keyed dry joints with both NC and SFRC, while the shear capacity of single-keyed dry joints with both NC and SFRC has been overestimated under the eccentric loads.
18
Taotao, Zhang, Luo Wenbo, Xiao Wei e Yan Ying. "Numerical simulation of single-lap adhesive joint of composite laminates". Journal of Reinforced Plastics and Composites 37, n. 8 (30 gennaio 2018): 520–32. http://dx.doi.org/10.1177/0731684418754358.
Testo completoAbstract (sommario):
A universal method is established to research the various possible damage modes of adhesive bond of laminated composites with or without z-pin reinforcements under tensile loads through numerical simulation. A Continuum Damage Mechanic model based on Hashin damage criterion as a user-defined subroutine is developed to simulate the damage of laminates and Z-pins. The Cohesive Zone Model is used to simulate the damage of adhesive damage, interlayer delamination, and Z-pin slipping-out phenomenon. The numerical simulation method is validated for simulating the various damage modes of the usual composite joints through comparing the simulated results and experiments. The research shows that different ply sequences induce different damage modes and ultimate failure loads of composite joints. The ultimate failure load of joint under tension is not affected obviously whether the joints are reinforced with or without z-pins. The reason is that the damage initiation usually locates at the two sides of adhesive zone and z-pins do not react on the reinforcement under tensile load of joint.
19
Iwasaki, Laura Rei, Michael Crosby, Yoly Gonzalez, Willard D. McCall, David B. Marx, Richard Ohrbach e Jeffrey Charles Nickel. "Temporomandibular joint loads in subjects with and without disc displacement". Orthopedic Reviews 1, n. 1 (1 dicembre 2009): 29. http://dx.doi.org/10.4081/or.2009.e29.
Testo completoAbstract (sommario):
The likelihood of development of degenerative joint disease (DJD) of the temporomandibular joint (TMJ) is related to the integrity of the TMJ disc. Predilection for mechanical failure of the TMJ disc may reflect inter-individual differences in TMJ loads. Nine females and eight males in each of normal TMJ disc position and bilateral disc displacement diagnostic groups consented to participate in our study. Disc position was determined by bilateral magnetic resonance images of the joints. Three-dimensional (3D) anatomical geometry of each subject was used in a validated computer-assisted numerical model to calculate ipsilateral and contralateral TMJ loads for a range of biting positions (incisor, canine, molar) and angles (1-13). Each TMJ load was a resultant vector at the anterosuperior-most mediolateral midpoint on the condyle and characterized in terms of magnitude and 3D orientation. Analysis of variance (ANOVA) was used to test for effects of biting position and angle on TMJ loads. Mean TMJ loads in subjects with disc displacement were 9.5-69% higher than in subjects with normal disc position. During canine biting, TMJ loads in subjects with disc displacement were 43% (ipsilateral condyle, p=0.029) and 49% (contralateral condyle, p=0.015) higher on average than in subjects with normal disc position. Biting angle effects showed that laterally directed forces on the dentition produced ipsilateral joint loads, which on average were 69% higher (p=0.002) compared to individuals with normal TMJ disc position. The data reported here describe large differences in TMJ loads between individuals with disc displacement and normal disc position. The results support future investigations of inter-individual differences in joint mechanics as a variable in the development of DJD of the TMJ.
20
Razavi, S. M. J., e F. Berto. "Experimental Investigation of Metallic Fiber-Reinforced Adhesively Bonded Joints under Bending". Key Engineering Materials 754 (settembre 2017): 252–55. http://dx.doi.org/10.4028/www.scientific.net/kem.754.252.
Testo completoAbstract (sommario):
In the current paper, the geometric and material parameters of metal fibers utilized for strengthening adhesively bonded single lap joints under flexural loading were investigated by using experimental investigations. According to the test results, incorporating metal fibers in the adhesive layer of a bonded joint can have a significant impact on the flexural load bearing of the joint. The distance between the fibers and also the fibers orientation were considered as the key parameters in this research. It was concluded that the load bearing of the joint can be improved by reducing the distance between the fibers and the highest failure loads were obtained for the joints reinforced by fibers in the longitudinal direction.
21
Gillette, Jason C., Catherine A. Stevermer, Ross H. Miller, W. Brent Edwards e Charles V. Schwab. "Lower Extremity Joint Moments During Carrying Tasks in Children". Journal of Applied Biomechanics 28, n. 2 (maggio 2012): 156–64. http://dx.doi.org/10.1123/jab.28.2.156.
Testo completoAbstract (sommario):
Farm youth often carry loads that are proportionally large and/or heavy, and field measurements have determined that these tasks are equivalent to industrial jobs with high injury risks. The purpose of this study was to determine the effects of age, load amount, and load symmetry on lower extremity joint moments during carrying tasks. Three age groups (8–10 years, 12–14 years, adults), three load amounts (0%, 10%, 20% BW), and three load symmetry levels (unilateral large bucket, unilateral small bucket, bilateral small buckets) were tested. Inverse dynamics was used to determine maximum ankle, knee, and hip joint moments. Ankle dorsiflexion, ankle inversion, ankle eversion, knee adduction, and hip extension moments were significantly higher in 8–10 and 12–14 year olds. Ankle plantar flexion, ankle inversion, knee extension, and hip extension moments were significantly increased at 10% and 20% BW loads. Knee and hip adduction moments were significantly increased at 10% and 20% BW loads when carrying a unilateral large bucket. Of particular concern are increased ankle inversion and eversion moments for children, along with increased knee and hip adduction moments for heavy, asymmetrical carrying tasks. Carrying loads bilaterally instead of unilaterally avoided increases in knee and hip adduction moments with increased load amount.
22
Pei, Shiling, Yongle Li, Yulong Bao, Xin Li e Shizhong Qiang. "Impact of train-induced vibration on railway cable-stayed bridges fatigue evaluation". Baltic Journal of Road and Bridge Engineering 11, n. 2 (27 giugno 2016): 102–10. http://dx.doi.org/10.3846/bjrbe.2016.12.
Testo completoAbstract (sommario):
Under repetitive heavy train traffic, railway steel truss bridges tend to have many fatigue related performance issues, especially at welded joints. Accurate estimation of the stress history at critical locations of welded joints under vehicle loading is important for joint fatigue design. Traditionally, vehicle loads were treated as moving static loads without considering their dynamic effects. In this study, a numerical procedure was introduced to incorporate the effect of dynamic response of the train–bridge coupled system on nodal fatigue damage. The proposed approach employs a twolevel modelling scheme which combines dynamic analysis for the full train-bridge system and detailed stress analysis at the joint. Miner rule was used to determine the cumulative fatigue damage at critical locations on the welded joint. A sensitivity analysis was conducted for different train loading configurations. It was determined that dynamic vibration negatively influences fatigue life. The calculated cumulative damage at investigated locations can more than the damage estimated using only static moving load method.
23
HAKKAK, FERAS, MOSTAFA ROSTAMI e MOHAMAD PARNIANPOUR. "ARE TIBIOFEMORAL COMPRESSIVE LOADS TRANSFERRED ONLY VIA CONTACT MECHANISMS?" Journal of Mechanics in Medicine and Biology 12, n. 04 (settembre 2012): 1250071. http://dx.doi.org/10.1142/s0219519412004971.
Testo completoAbstract (sommario):
The tibiofemoral joint is known to bear compressive loads of several body-weights during daily activities. These forces are known to be transferred through the joint via compression of the tibial and femoral surfaces against one another. The menisci are also known to enhance this process by increasing the contact area and decreasing contact stress. However, calculations presented in this paper suggest that the load-bearing capacity of contact mechanisms is seemingly several times smaller than tibiofemoral joint loads. This suggests that probably one or more non-contact load-bearing mechanism(s) exist, and share the load with the already known contact mechanisms.
24
Sun, Hui B., Luis Cardoso e Hiroki Yokota. "Mechanical Intervention for Maintenance of Cartilage and Bone". Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders 4 (gennaio 2011): CMAMD.S6982. http://dx.doi.org/10.4137/cmamd.s6982.
Testo completoAbstract (sommario):
Mechanical loading provides indispensible stimuli for growth and development of the articular cartilage and bone. Interestingly, depending on loading conditions loads applied to the joint can be beneficial as well as harmful to skeletal maintenance and remodeling. Moderate loads to the synovial joint, for instance, suppress the expression levels of matrix metallproteinases (MMPs), while loads above a threshold tend to increase their destructive activities. This report focuses on two recently developed loading modalities from animal studies, joint motion and joint loading. Their unique characteristics and potential usages for maintenance of the articular cartilage and stimulation of bone remodeling are reviewed. Also described are biophysical and molecular mechanisms which likely are responsible for the load-driven maintenance of cartilage and bone, and a possibility of developing load-mediated treatments of osteoporosis and osteoarthritis.
25
Paslay, P. R., e E. P. Cernocky. "Prediction of Wear and Stresses While Drilling Through a Riser Flex Joint". Journal of Energy Resources Technology 116, n. 1 (1 marzo 1994): 49–55. http://dx.doi.org/10.1115/1.2906009.
Testo completoAbstract (sommario):
Flex joints in risers introduce abrupt directional changes along the drillstring. High drillstring stresses and flex joint wear rates are introduced, particularly when the drillstring tension is high. An analysis procedure is presented which finds the drillstring/flex joint contact loads in the vicinity of the flex joint as a function of the tension in the drillstring at the flex joint. The tensile and contact loads of the drillstring at the riser are used to estimate the wear rate on the flex joint and the axial and bending stresses in the drillstring. This example shows the value of the procedure in estimating maximum allowable angles for the flex joint.
26
Wang, Tao, Xue Gong, Shude Ji, Gang Xue e Zan Lv. "Friction stir lap welding thin aluminum alloy sheets". High Temperature Materials and Processes 39, n. 1 (23 dicembre 2020): 663–70. http://dx.doi.org/10.1515/htmp-2020-0024.
Testo completoAbstract (sommario):
AbstractIn this work, thin aluminum alloy sheets with thickness of 0.8 mm were friction stir lap welded using small shoulder plunge depths of 0 and 0.1 mm. The joint formation, microstructure and mechanical properties were investigated. Results show that voids appear inside the stir zone when the small plunge depth of 0 mm is used because the tool shoulder cannot exert a good material-collecting effect at such low plunge depth. A plunge depth of 0.1 mm causes tight contact between the shoulder and the material and thus results in good material-collecting effect, which is helpful to eliminate the void. Sound joints are attained at a wide range of welding parameters when using the shoulder plunge depth of 0.1 mm. No crack is observed inside the bonding ligament. The joints own higher failure loads when the retreating side (RS) of the joint bares the main load during the lap shear tests. The shear failure load first increases and then decreases with increasing the rotating and welding speeds, and the maximum failure load of 6419 N is obtained at 600 rpm and 150 mm/min. The hardness of the joint presents a “W” morphology and the minimum hardness is obtained at the heat affected zone. The joints present tensile fracture and shear fracture when the advancing side and RS bare the main loads, respectively.
27
Hollis, J. M. "A Six-Degree-of-Freedom Test System for the Study of Joint Mechanics and Ligament Forces". Journal of Biomechanical Engineering 117, n. 4 (1 novembre 1995): 383–89. http://dx.doi.org/10.1115/1.2794196.
Testo completoAbstract (sommario):
A joint testing system was designed to transmit a specified motion or force to a joint in all six degrees of freedom (d.o.f.) using a spatial linkage system for position feedback. The precise reproducibility of position provided by this method of position feedback allows determination of in situ ligament forces for external joint loadings. Load on the structure of interest is calculated from six d.o.f. load cell output after the loaded position is reproduced with all other structures removed. In a test of this system, measured loads showed good agreement with applied loads.
28
Tan, Yingliang, Bing Zhu, Tingyi Yan, Biao Huang, Xuewei Wang, Wenwei Yang e Bo Huang. "Experimental Study of the Mechanical Behavior of the Steel–Concrete Joints in a Composite Truss Bridge". Applied Sciences 9, n. 5 (27 febbraio 2019): 854. http://dx.doi.org/10.3390/app9050854.
Testo completoAbstract (sommario):
The mechanical behavior of the steel–concrete joints in a composite bridge was investigated. Pull-out tests on eight specimens were carried out to evaluate the connection performance of Perfobond rib shear connectors (PBL shear connectors). In addition, static load tests were conducted on three composite joint specimens with a scale of 1/2 in a composite truss bridge. The crack load, load–displacement curves, strain distribution, and the joint stiffness were obtained from the composite joint to analyze the mechanical behavior of steel–concrete joints. The experimental results show that the embedded depth plays an important role in the ultimate bearing capacity and the deformation of PBL shear connectors and could even change the failure mode. Based on the test results of composite joints, the displacement increased almost linearly with the horizontal load on the concrete chord. There was no evident failure, and large deformation occurred in composite joints. In addition, the ultimate loads obtained from three composite joint specimens were greater than 2.93 times the design load (2050 kN). These investigated composite joints had excellent bearing capacity (above 6000 kN). This study will provide an experimental reference for the design of steel–concrete joints for composite truss bridges.
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Guérinot, Alexandre E., Spencer P. Magleby, Larry L. Howell e Robert H. Todd. "Compliant Joint Design Principles for High Compressive Load Situations". Journal of Mechanical Design 127, n. 4 (17 giugno 2004): 774–81. http://dx.doi.org/10.1115/1.1862677.
Testo completoAbstract (sommario):
Buckling failure has been a major obstacle in designing compliant joints in high compression applications. This paper describes two principles, isolation and inversion, that can be successfully applied to many compliant joints to increase their ability to withstand high compressive loads by avoiding buckling-prone loading conditions. Isolation and inversion give rise to a new breed of compliant joints called high compression compliant mechanisms (HCCM). HCCMs have many of the inherent advantages of compliant mechanisms with the additional qualities of high load-bearing joints. This added robustness in compression can be achieved without adversely affecting the kinematic behavior of the joint.
30
Kang, Heesuk, Paul Park, Frank La Marca, Scott J. Hollister e Chia-Ying Lin. "Analysis of load sharing on uncovertebral and facet joints at the C5–6 level with implantation of the Bryan, Prestige LP, or ProDisc-C cervical disc prosthesis: an in vivo image-based finite element study". Neurosurgical Focus 28, n. 6 (giugno 2010): E9. http://dx.doi.org/10.3171/2010.3.focus1046.
Testo completoAbstract (sommario):
Object The goal of this study was to evaluate and compare load sharing of the facet and uncovertebral joints after total cervical disc arthroplasty using 3 different implant designs. Methods Three-dimensional voxel finite element models were built for the C5–6 spine unit based on CT images acquired from a candidate patient for cervical disc arthroplasty. Models of facet and uncovertebral joints were added and artificial discs were placed in the intervertebral disc space. Finite element analyses were conducted under normal physiological loads for flexion, extension, and lateral bending to evaluate von Mises stresses and strain energy density (SED) levels at the joints. Results The Bryan disc imposed the greatest average stress and SED levels at facet and uncovertebral joints with flexion-extension and lateral bending, while the ProDisc-C and Prestige LP discs transferred less load due to their rigid cores. However, all artificial discs showed increased loads at the joints in lateral bending, which may be attributed to direct impinging contact force. Conclusions In unconstrained/semiconstrained prostheses with different core rigidity, the shared loads at the joints differ, and greater flexibility may result in greater joint loads. With respect to the 3 artificial discs studied, load sharing of the Bryan disc was highest and was closest to normal load sharing with the facet and uncovertebral joints. The Prestige LP and ProDisc-C carried more load through their rigid core, resulting in decreased load transmission to the facet and uncovertebral joints.
31
Chapman, Ian, John Newnham e Paul Wallace. "The Tightening of Bolts to Yield and Their Performance Under Load". Journal of Vibration and Acoustics 108, n. 2 (1 aprile 1986): 213–21. http://dx.doi.org/10.1115/1.3269326.
Testo completoAbstract (sommario):
The mechanism of tightening bolted joints and the stress distribution in the bolt are analyzed. Measurements were made of static and dynamic strength of joints. It is shown that all bolts behave elastically when external loads are applied to the joint even when the fastener was tightened to its torque-tension yield point. It is shown that joints generally fail when the external loads are sufficient to overcome the bolt preload. Fatigue reesults show that joint fatigue strength increases with preload, and that high fatigue bolts gave an improvement over standard fasteners at all preloads.
32
Abid, Muhammad. "STAMINA OF A GASKETED BOLTED FLANGED PIPE JOINT UNDER DYNAMIC LOADING". IIUM Engineering Journal 17, n. 2 (30 novembre 2016): 137–55. http://dx.doi.org/10.31436/iiumej.v17i2.565.
Testo completoAbstract (sommario):
Gasketed bolted flange joints are the most critical components in pipelines for their sealing and strength under operating conditions. Most of the work available in literature is under static loading, whereas in industry, cyclic loads are applied due to the vibrating machinery such as motors, pumps, sloshing in offshore applications and in the ships etc. In this study a three dimensional finite element analysis of a gasketed joint is carried out using a spiral wound gasket under bolt up and dynamic operating conditions (internal pressure, axial and bending) singly and in combination. The cyclic axial loads are concluded relatively more challenging for both the sealing and strength of the joint. Higher magnitudes of loads and frequencies are also observed more challenging to the joints performance.
33
Synek, Alexander, Szu-Ching Lu, Sandra Nauwelaerts, Dieter H. Pahr e Tracy L. Kivell. "Metacarpophalangeal joint loads during bonobo locomotion: model predictions versus proxies". Journal of The Royal Society Interface 17, n. 164 (marzo 2020): 20200032. http://dx.doi.org/10.1098/rsif.2020.0032.
Testo completoAbstract (sommario):
The analysis of internal trabecular and cortical bone has been an informative tool for drawing inferences about behaviour in extant and fossil primate taxa. Within the hand, metacarpal bone architecture has been shown to correlate well with primate locomotion; however, the extent of morphological differences across taxa is unexpectedly small given the variability in hand use. One explanation for this observation is that the activity-related differences in the joint loads acting on the bone are simply smaller than estimated based on commonly used proxies (i.e. external loading and joint posture), which neglect the influence of muscle forces. In this study, experimental data and a musculoskeletal finger model are used to test this hypothesis by comparing differences between climbing and knuckle-walking locomotion of captive bonobos ( Pan paniscus ) based on (i) joint load magnitude and direction predicted by the models and (ii) proxy estimations. The results showed that the activity-related differences in predicted joint loads are indeed much smaller than the proxies would suggest, with joint load magnitudes being almost identical between the two locomotor modes. Differences in joint load directions were smaller but still evident, indicating that joint load directions might be a more robust indicator of variation in hand use than joint load magnitudes. Overall, this study emphasizes the importance of including muscular forces in the interpretation of skeletal remains and promotes the use of musculoskeletal models for correct functional interpretations.
34
Jung, Dal Woo, e Nak Sam Choi. "Fracture Characteristics of a Hybrid Composite Joint Beam for the Tilting Car Body under Static and Fatigue Transverse Loads". Key Engineering Materials 353-358 (settembre 2007): 2681–84. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2681.
Testo completoAbstract (sommario):
Fatigue fracture behavior of a hybrid joint beam for the tilting car body was evaluated in comparison to the case of static fracture. Specimen beams of the hybrid joint part attached in the real tilting car body were fabricated for the bending test. Characteristic fracture behaviors of hybrid joint beam specimens under cyclic transverse loads were very different from the case under static loads. Static transverse load caused shear deformation and fracture in the honeycomb core region, while cyclic transverse load brought about delamination along the interface between composite skin and honeycomb core layers as well as fracture of the welded joint. Fracture characteristics obtained by the transverse fatigue tests were reflected for improving the hybrid joint structure in the real tilting car body.
35
Welch, Michael. "Classical analysis of preloaded bolted joint load distributions". International Journal of Structural Integrity 9, n. 4 (13 agosto 2018): 455–64. http://dx.doi.org/10.1108/ijsi-07-2017-0045.
Testo completoAbstract (sommario):
Purpose The purpose of this paper is to develop the understanding of how external loads are reacted through preloaded bolted joints and the interaction of the joint elements. The paper develops ideas from how to do an analysis to understanding the implications of the results. Design/methodology/approach Classical methods of analysis are applied to preloaded bolted joints, made with multiple bolts. The paper considers both the detailed analysis of bolts stresses, fatigue analysis and load-based design analysis, to demonstrate the structural integrity of preloaded bolted joints. Findings In preloaded joints the external tensile axial load and moments are mainly supported by changes in contact pressure at the faying surface. Only a small proportion of the external loads produce changes in bolt tensile stress. The bolts have a significant mean stress but experience a low working stress range. This low stress range is a factor in explaning why preloaded bolted joints have good fatigue performance. Practical implications In many cases the methods presented are adequate to demonstrate the structural integrity of joints. In some cases finite element methods may be more appropriate, and the methods discussed can be used in the validation process. Originality/value The paper brings together a number of concepts and links them into a practical design analysis process for preloaded bolted joints. Interpretation of results, within the context of design standards, is provided.
36
Shah, Darshan S., Orçun Taylan, Matthias Verstraete, Pieter Berger, Hilde Vandenneucker e Lennart Scheys. "Can Intraoperative Intra-Articular Loads Predict Postoperative Knee Joint Laxity Following Total Knee Arthroplasty? A Cadaver Study with Smart Tibial Trays". Sensors 21, n. 15 (27 luglio 2021): 5078. http://dx.doi.org/10.3390/s21155078.
Testo completoAbstract (sommario):
Ligament balancing during total knee arthroplasty (TKA) often relies on subjective surgeon experience. Although instrumented tibial trays facilitate an objective assessment of intraoperative joint balance through quantification of intra-articular joint loads, postoperative clinical assessment of joint balance relies on passive stress tests quantifying varus–valgus joint laxity. This study aimed at correlating the intraoperative and postoperative metrics used to assess joint balance while also comparing joint loads obtained during passive assessment and active functional motions. Four experienced surgical fellows were assigned a fresh-frozen lower limb each to plan and perform posterior-stabilised TKA. An instrumented tibial insert measured intraoperative intra-articular loads. Specimens were then subjected to passive flexion–extension, open-chain extension, active squatting, and varus–valgus laxity tests on a validated knee simulator. Intra-articular loads were recorded using the instrumented insert and tibiofemoral kinematics using an optical motion capture system. A negative correlation was observed between mean intraoperative intra-articular loads and corresponding mean postoperative tibial abduction angle during laxity tests (medial: R = −0.93, p = 0.02; lateral: R = −0.88, p = 0.04); however, this was not observed for each specimen. Peak intra-articular load distribution for active squatting was lateral-heavy, contrasting to the medial-heavy distribution observed in passive intraoperative measurements, for all specimens. These aspects should be given due consideration while assessing intraoperative and postoperative joint stability following TKA.
37
Devesa-Garcia, V., P. G. Urrutia, F. San Roman, J. Rodriguez-Quiros e G. L. Rovesti. "Evaluation of a distractor to increase joint space of the stifle joint in dogs: a cadaveric study". Veterinary and Comparative Orthopaedics and Traumatology 28, n. 03 (2015): 179–85. http://dx.doi.org/10.3415/vcot-14-04-0058.
Testo completoAbstract (sommario):
SummaryObjective: To evaluate the technical feasibility and efficacy of a joint distraction technique to increase the stifle joint space and assess potential soft tissue damage due to the distraction.Methods: Twenty stifle joints of twelve canine cadavers without evidence of disease were radiographically evaluated by medio-lateral, cranio-caudal and varus-valgus stressed projections. Joint distraction was applied with loads from 40 N up to 200 N, and the joint space achieved was measured on radiographic images. Distraction plus distension with saline was subsequently applied and measured. Varus-valgus stressed projections were repeated after distraction to evaluate a potential increase in joint laxity.Results: Distraction produced a significant increase of the joint space for most of the evaluated loads. Distraction plus distension produced a significant increase for most of the loads compared to the distraction alone. No ensuing joint laxity could be inferred from the post-distraction radiographic evaluation.Clinical significance: Stifle distraction produces an increase of the joint space, which is wider when intra-articular saline is injected. This may be potentially useful for improving joint structure visualization and facilitating arthroscopic procedures, thus reducing the potential for iatrogenic damage to intra articular structures. No soft tissue damage could be inferred by radiographic pre- and post-procedure comparison. Further clinical studies are required to evaluate potential neurovascular complications.
38
Biscarini, Andrea. "Dynamic Effects of Muscle Moment Arm Variation and Heavy External Loads on Hinge Joints". Journal of Applied Biomechanics 19, n. 3 (agosto 2003): 223–38. http://dx.doi.org/10.1123/jab.19.3.223.
Testo completoAbstract (sommario):
A two-dimensional model has been developed to predict and explain the effects of the variation of muscle moment arms during dynamic exercises involving heavy external loads. The analytical dependence of the muscle moment arm on the joint angle and on the origin and insertion position was derived for an ideal uniaxial hinge joint, modeling the muscle as a cable following an idealized minimum distance path from the origin to insertion that wraps around the bony geometry. Analytical expressions for the ratios of muscular force and the joint restraining reaction components to the external load weight were deduced, for isokinetic and static exercises, as a function of joint angle, joint angular velocity, and the other geometric parameters defining the model. Therefore, external load weight, joint angular velocity, and constraints to joint range of motion may be adjusted reciprocally in order to control in advance the peak value of the components of the joint load during isokinetic exercises. A dynamic formulation of forearm flexion/extension was solved numerically under the condition of constant biceps force in order to highlight the key role played by the variation in muscle moment arm in preventing injury during lifting of external loads against gravity. For example, our analysis indicates that the mean and peak resultant joint loads decrease by 5% and 14%, respectively, as a result of the change in muscle moment arm that occurs over the range of motion.
39
Newnham, J., e L. Curley. "Bolted Joints Under Tensile Service Loads: The Effect of Torsion in the Bolt on In-Service Clamping Loads". Journal of Mechanical Design 115, n. 1 (1 marzo 1993): 36–40. http://dx.doi.org/10.1115/1.2919321.
Testo completoAbstract (sommario):
In order to determine how bolted joints behave under conditions of tensile external loading, tests were conducted on bolts which had been tightened into joints by means of (a) elastic range, (b) yield, and (c) over-yielding tightening. The loading tests showed that the maximum clamp load which the bolt would exert on the joint without permanent extension was the uniaxial tensile yield load of the bolt. This was observed even when torsional stress was present in the as-tightened bolt, and for all three tightening methods.
40
Ritter, George W., David R. Speth e Yu Ping Yang. "Qualifications of Adhesives for Marine Composite-to-Steel Bonded Applications". Journal of Ship Production 25, n. 04 (1 novembre 2009): 198–205. http://dx.doi.org/10.5957/jsp.2009.25.4.198.
Testo completoAbstract (sommario):
This paper describes a straightforward method for the design and certification of adhesively bonded composite to steel joints for the marine industry. Normally, certification is based on documented service at sea. Since these joints have not been previously deployed at sea, no data on their performance exist. Using an integrated combination of mechanical property evaluation and finite element modeling, the load- bearing capacity of a joint can be compared with the anticipated seaway loads. Calculated factors of safety for the sandwich design used here show that the joint has adequate strength to maintain structural integrity even after severe environmental exposure.
41
Wang, Peiyan, Shile Yao, Xinmei Wang e Zhufeng Yue. "Experimental Research and Numerical Simulation of Wing Boxes under Pure Bending Load". Advances in Mechanical Engineering 6 (1 gennaio 2014): 274748. http://dx.doi.org/10.1155/2014/274748.
Testo completoAbstract (sommario):
Two full-scale wing boxes with different types of butt joints were investigated under pure bending load, and numerical methods, including global analysis and detailed analysis, were proposed to determine the reasons for failure of the wing boxes. Wing boxes were tested under bending loads applied by a multichannel force control system. The experimental results showed that the region of the butt joint was the weakest location of the wing boxes, and the damage loads were far less than the design load. The global analysis and detailed analysis were carried out on the wing boxes, focusing on the region of the butt joint, to determine the reasons for failure. Global analysis in explicit dynamic modulus was adopted to simulate the loading process of the two wing boxes. Meanwhile, detailed finite element models created in Patran/Nastran were used to evaluate the stability. Comparing experimental results with numerical counterparts, it is shown that the failure of the wing boxes is induced by local buckling occurring around the butt joint. In addition, the wing box that uses butt joints with lap jointed sheets is more rigid than that without lap jointed sheets, and the stress distribution is more uniform. The numerical analysis proposed by the paper can help with structure design in preliminary assessment.
42
Yang, Xiuren, Fang Lin e Meiqun Huang. "Experimental Analysis of Bending Stiffness Characteristics of Grouted Double Mortise-Tenon Joint for Prefabricated Metro Station Structure". Advances in Civil Engineering 2021 (23 giugno 2021): 1–13. http://dx.doi.org/10.1155/2021/9958436.
Testo completoAbstract (sommario):
The grouted mortise-tenon joint, invented as the connection between the large prefabricated components, is the key to the prefabricated underground structures, and the double-tenon joint is most widely used in the prefabricated metro station structure. This paper conducts characteristic analysis of bending stiffness with a 1 : 1 prototype test in key working direction of different joint types for grouted double mortise-tenon joint. The results show that the double-tenon joint is characteristic of variable stiffness under different loads. Change laws of double-tenon joint bending stiffness without and with auxiliary pretightening device in tension side and compression side are also discussed. The correlations for calculating double-tenon joint bending stiffness with various axial loads and bending moments are derived at last, which offers the theory foreshadowing of similar joints.
43
Pan, Jian Rong, Zhan Wang, Lin Qiang Zheng e Zheng Ting Yang. "Finite Element Analysis of Beam-Column Connection with Cantilever Beam Splicing". Advanced Materials Research 838-841 (novembre 2013): 540–44. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.540.
Testo completoAbstract (sommario):
Beam-column connection with cantilever beam bolted-splicing is also known as the joint of column-tree moment-resisting frame. The study is still relatively small for the semi-rigid behavior and rotational stiffness of the joint. This paper deal with four specimens of the joints with cantilever beam splicing and four specimens of the welded joints by using three dimensional finite element model analysis. The strain, stress, yield and ultimate loads, yield and ultimate deformations had been compared between the joint with cantilever beam splicing and the welded joint. The analysis results show that, when the splicing area of the joint with cantilever beam splicing was designed more strongly, the stress distribution, the load-displacement curves in elastic working stage, and the initial rotational stiffness are good agreement between the joint with cantilever beam splicing and the welded joint. The hysteresis curves of the joint with cantilever beam splicing were inverse S-shaped, indicating that there was greater slipping deformation because of bolt splicing. The welded joint had no slipping phenomenon.
44
Jung, Dal Woo, e Nak Sam Choi. "Static and Fatigue Analysis of a Hybrid Joint Part for the Tilting Car Body". Key Engineering Materials 353-358 (settembre 2007): 2860–63. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.2860.
Testo completoAbstract (sommario):
Fatigue fracture behavior of a hybrid joint part for the tilting car body was evaluated in comparison to the case of static fracture. The specimens of hybrid joint part applied in the real tilting car body were fabricated for the bending test. Characteristic fracture behaviors of hybrid joint part specimens under cyclic loads were obviously different from the case under static loads. Static bending load caused the shear deformation and fracture in the honeycomb core region, while cyclic bending load did the delamination along the interface between composite skin and honeycomb core layers as well as the fracture of welded joint part. Experimental results obtained by static and fatigue tests were reflected in modifications of design parameters of the hybrid joint structure in the real tilting car body.
45
Sevrez, Violaine, Guillaume Rao, Eric Berton e Reinoud J. Bootsma. "On the Organizing Role of Nonmuscular Forces During Performance of a Giant Circle in Gymnastics". Journal of Applied Biomechanics 28, n. 1 (febbraio 2012): 57–62. http://dx.doi.org/10.1123/jab.28.1.57.
Testo completoAbstract (sommario):
Five elite gymnasts performed giant circles on the high bar under different conditions of loading (without and with 6-kg loads attached to the shoulders, waist or ankles). Comparing the gymnasts’ kinematic pattern of movement with that of a triple-pendulum moving under the sole influence of nonmuscular forces revealed qualitative similarities, including the adoption of an arched position during the downswing and a piked position during the upswing. The structuring role of nonmuscular forces in the organization of movement was further reinforced by the results of an inverse dynamics analysis, assessing the contributions of gravitational, inertial and muscular components to the net joint torques. Adding loads at the level of the shoulders, waist or ankles systematically influenced movement kinematics and net joint torques. However, with the loads attached at the level of the shoulders or waist, the load-induced changes in gravitational and inertial torques provided the required increase in net joint torque, thereby allowing the muscular torques to remain unchanged. With the loads attached at the level of the ankles, this was no longer the case and the gymnasts increased the muscular torques at the shoulder and hip joints. Together, these results demonstrate that expert gymnasts skillfully exploit the operative nonmuscular forces, employing muscle force only in the capacity of complementary forces needed to perform the task.
46
Bach, J. M., e M. L. Hull. "A New Load Application System for In Vitro Study of Ligamentous Injuries to the Human Knee Joint". Journal of Biomechanical Engineering 117, n. 4 (1 novembre 1995): 373–82. http://dx.doi.org/10.1115/1.2794195.
Testo completoAbstract (sommario):
This paper describes the design and accuracy evaluation of a new six degree of freedom load application system for in vitro testing of the human knee joint. External loads of both polarity in all six degrees of freedom can be applied either individually or in any combination while the knee is permitted to move unconstrained in response to applied loads. The flexion/extension degree of freedom permits the full physiological range of motion. In addition to external loads, forces of the three major muscle groups (quadriceps, hamstrings, gastrocnemius) crossing the joint can be developed. Full automation and rapid convergence of loads to programmed values are achieved through a computer which feeds command signals to servo controller/electro-pneumatic servo valves. The servo valves regulate pressure to pneumatic actuators which develop the various loads. Experiments undertaken to quantify the accuracy of both load and displacement measurements reveal that errors particularly in load measurement are effectively controlled through the apparatus design.
47
Welch, Michael. "A Paradigm for the Analysis of Preloaded Bolted Joints". Strojnícky casopis – Journal of Mechanical Engineering 69, n. 1 (1 maggio 2019): 143–52. http://dx.doi.org/10.2478/scjme-2019-0012.
Testo completoAbstract (sommario):
AbstractThe purpose of this paper is to present a paradigm, or guide, to the analysis of preloaded bolted joints made using multiple bolts. Classical analysis methods are applied to the interaction of the joint elements subjected to combinations of both in-plane and out-of-plane loads and moments. The distribution of the external loads and moments within the preloaded joint is determined in relationship to individual bolts. An analysis of loads and stresses in individual bolts and dowels along with flange bending and thread shear in tapped or threaded holes is developed. The article brings together a number of concepts and links them into a practical design analysis process that is applicable for many cases of preloaded bolted joints and are adequate to demonstrate the structural integrity of each element of the joint. Interpretation of results, within the context of design standards, is provided. In some cases finite element methods may be more appropriate, and the methods discussed can be used in the validation process.
48
Koves, W. J. "Analysis of Flange Joints Under External Loads". Journal of Pressure Vessel Technology 118, n. 1 (1 febbraio 1996): 59–63. http://dx.doi.org/10.1115/1.2842164.
Testo completoAbstract (sommario):
Flange joint leakage is one of the common maintenance problems in refineries and chemical plants. This paper studies the effect of external loads on the strength and leakage behavior of flanged joints. Finite element and analytical methods are compared, and the proposed method is compared with leakage data. The common “equivalent pressure” method is shown to be very conservative, and a method of evaluating external loads is recommended.
49
Gabriel, Stefan M., Anton G. Clifford, William J. Maloney, Mary K. O’Connell e Paul Tornetta. "Unloading the Osteoarthritic Knee with a Novel Implant System". Journal of Applied Biomechanics 29, n. 6 (dicembre 2013): 647–54. http://dx.doi.org/10.1123/jab.29.6.647.
Testo completoAbstract (sommario):
Medial knee osteoarthritis (OA) is a common disorder often associated with pathologic joint loading. Insoles, braces, and high tibial osteotomy are OA treatments aimed at reducing medial joint loads, but their use and effectiveness are limited. The KineSpring System implant also intends to reduce knee loads in OA patients while overcoming those limitations. The current study was undertaken to test the implant’s effect on loads at the knee. Six cadaver knees with Outerbridge Grade I-II medial OA were subjected to simulated gait using a kinematic test system. Knees were tested with and without the medial knee implant while thin film sensors measured medial and lateral femorotibial contact pressures. Significant medial compartment load reductions (134 ± 53 N [P= .002]) were found throughout the stance phase of gait in the treated knee. Significant total joint load decreases (91 ± 40 N [P= .002]) were also observed without substantial changes in lateral compartment loads. These significant reductions of medial and total intra-articular loads are also within clinically effective ranges of other unloading systems. This suggests that the KineSpring System could be a viable treatment for medial knee OA.
50
Hong, J. S., H. I. Choi e K. J. Chun. "PS6-13 STUDY ON JOINT SPEED AND IMPACT LOADS ON JOINTS DURING FALLING(PS6: Poster Short Presentation VI,Poster Session)". Proceedings of the Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics 2015.8 (2015): 330. http://dx.doi.org/10.1299/jsmeapbio.2015.8.330.
Testo completo