Torsion Testing Machine Research Articles

Fatigue crack initiation and propagation of 100Cr6 steel under torsional loading in very high cycle regime

Cyclic torsional fatigue properties of a high strength steel 100Cr6 are investigated using an ultrasonic torsional fatigue testing machine, and the results are compared with those obtained with fatigue tests under axial loading. Fatigue crack initiation and growth under torsion loading are observed in the very high cycle regime. Results show that fatigue cracks initiated from specimen surface as well as subsurface inclusions under torsion loading. However, subsurface MnS inclusions play a dominant role in crack initiation under torsion loading in the very high cycle regime. The initiation and early propagation of fatigue cracks are mostly controlled by the direction of the maximum shear stress. For surface crack initiation, cracks initiated in parallel to the longitudinal direction of the specimens. Once the shear crack propagated to a crack length of about 20-30 μm, crack branched to the angle close to the direction perpendicular to the remote maximum principal stresses. As for the subsurface fatigue crack initiation, the cracks parallel to the longitudinal direction of the specimens could not be observed, and crack propagation followed a spiral shape on a plane with an orientation of 45° with respect to the loading direction, which corresponds to the maximum principal stress plane.

An Experimental Study of Torsional Properties of Polyvinylchloride

In this research, an experimental study has been performed to investigate the mechanical properties through torsion testing of polyvinylchloride (PVC) polymer specimens. For the purpose of the experimentation, specimens of PVC round bars have been prepared. Torsion testing machine apparatus of 200 Nm motor driven was used to evaluate the torsion properties of the tested bars. The apparatus provides four deformation speeds of 50°/min, 100°/min, 200°/min and 500 °/min. The tests conducted under different conditions in a room temperature and cooling of the samples and tested at different deformation speeds given by the torsion apparatus. Various tests produce the torsional moment- angle of rotation diagrams and thereafter both of torsional fracture resistance and shear modulus have been calculated. The results showed the effect of temperature change on the mechanical properties of PVC by making the material harder and can resist higher value of the applied torque where the range is from 2.9 N.m for the cooled sample to 2 N.m for the received samples tested at room temperature. Moreover the results showed an increase of shear modulus to 282 MPa for the cooled samples in compare to 140 MPa for as received samples. Finally the results provide a guideline for designers on how to use parts made of PVC in different applications where the range of both the maximum torque and failure torque with their mechanical properties of rigidity and torsional resistance were recorded.

Development of ultrasonic torsional fatigue testing machine with mean torsional stress

Development of ultrasonic torsional fatigue testing machine with mean torsional stress

Biomechanics of Fractures.

This video presents the digitized, original, reel-to-reel footage of Victor Frankel's groundbreaking 1960s experiments demonstrating the viscoelastic properties and fracture mechanics of loaded bone. As can be seen, novel instrumentation was used that resulted in an easily reproducible method of controlling bone loading rates. The innovation, and associated experiments, radically advanced our understanding of the mechanisms of acute fractures and bone's response to energy. Using the "Standard Torsion Testing Machine" that he helped design, the author explains how the mechanical and functional properties of bone are affected by various defects. Examples used include an intact dog femur, a femur with a hole in the cortex, and a femur with an open section defect. Slow motion depiction allows the viewer to appreciate the potential soft tissue damage associated with bone fragmentation and how this varies with energy input. The video concludes with a demonstration of the effect of torsional motion on the vasculature. Graphs produced by the torsion tester display torque versus angular deformation plots for each experiment. These illustrate the relationship between bone structure, fracture, and energy. The x-ray contrast segment provides an example of associated arterial damage secondary to a fracture. This previously unreleased piece of orthopaedic history provides viewers with perspective on the early days of biomechanical study and an easy-to-understand tutorial on acute fracture mechanics and the role of energy in injury.

Experimental &FEA Assessment of Modification in Portal Axle Shaft

Portal axles (or portal gear) are designed for off-road driving conditions. The axle tube is above the center of the wheel hub and a reduction gearbox present within the hub. Axle tube is installed between the wheel and the axle shaft to give more ground clearance to the vehicle. It is the shaft which must have higher strength and toughness.Since composite materials are having promising properties, which can reduce the weight and almost equal to conventional material properties. In this paper portal axle shaft is analyzed by Finite Element Analysis considering varying parameters i.e. rib thickness and hollow shaft thickness and are consider. Some of the parameters are kept constant which are the depth of spokes, the rib fillet radius and the number of spokes. The Torsional strength of the shaft compared for three different models.The modeling and simulation of spur gears in placed portal axle is important to predict the actual motion behavior. However, gear train design in portal axle is difficult to study comprehensively due to their relatively low cost and short product life cycle. In this study, modal analysis of portal axle shaft is simulated using Finite Element Method(FEM). Keywords:EN-24, FEM, torsion test, Taguchi approach, Torsion Testing Machine. I. Introduction A portal axle unit is installed between the wheel and the axle shaft to give higher ground clearance to the vehicle. It allows driving on off-road so that the vehicle can go over high terrains and obstacles. Compared to normal axel, portal axles enable the vehicle to gain a higher ground clearance, as both axel tube and differential casing are tucked up higher under the vehicle. The difference between normal axel and portal axel are showed in the below figure1

The Mechanical Effect of Rod Contouring on Rod-Screw System Strength in Spine Fixation.

ObjectiveRod-screw fixation systems are widely used for spinal instrumentation. Although many biomechanical studies on rod-screw systems have been carried out, but the effects of rod contouring on the construct strength is still not very well defined in the literature. This work examines the mechanical impact of straight, 20° kyphotic, and 20° lordotic rod contouring on rod-screw fixation systems, by forming a corpectomy model.MethodsThe corpectomy groups were prepared using ultra-high molecular weight polyethylene samples. Non-destructive loads were applied during flexion/extension and torsion testing. Spine-loading conditions were simulated by load subjections of 100 N with a velocity of 5 mm min-1, to ensure 8.4-Nm moment. For torsional loading, the corpectomy models were subjected to rotational displacement of 0.5° s-1 to an end point of 5.0°, in a torsion testing machine.ResultsUnder both flexion and extension loading conditions the stiffness values for the lordotic rod-screw system were the highest. Under torsional loading conditions, the lordotic rod-screw system exhibited the highest torsional rigidity.ConclusionWe concluded that the lordotic rod-screw system was the most rigid among the systems tested and the risk of rod and screw failure is much higher in the kyphotic rod-screw systems. Further biomechanical studies should be attempted to compare between different rod kyphotic angles to minimize the kyphotic rod failure rate and to offer a more stable and rigid rod-screw construct models for surgical application in the kyphotic vertebrae.

曲げ・ねじり組合せ疲労試験装置を用いたSUS304の非比例多軸高サイクル疲労寿命

曲げ・ねじり組合せ疲労試験装置を用いたSUS304の非比例多軸高サイクル疲労寿命

高強度鋼の超高サイクルフレッティング疲労に関する研究

In fretting fatigue, fatigue limit is, in general, considered to disappear. Several researchers, however, have reported that there could be the critical stress intensity factor range that is a threshold where a fretting fatigue crack is arrested within tens of micrometer. In this study, non-propagating fretting fatigue cracks of high strength steel were examined in the very high cycle regime. Fretting fatigue tests were conducted by using an ultrasonic torsional fatigue testing machine to accelerate fatigue tests. Fretting fatigue cracks were initiated in the early stage of the fatigue life of a specimen. For run-out specimens in the very high cycle regime, fatigue cracks were still observed in the fretting regime.

軸受鋼の繰返し往復すべり接触における摩擦挙動と表面損傷

Delamination failure is one of the most important engineering issues for rolling contact machine elements. It is known that this failure is intimately related to shear-mode (mode II and mode III) fatigue crack growth. Generally, the shear-mode fatigue crack growth behavior and its threshold condition can be greatly influenced by the crack face interference. Therefore, understanding of the mechanism of friction and surface damage of crack faces is of importance and a new testing method that can examine appropriately these properties is required. In this study, the influences of the cyclic reciprocating sliding contact with micro-scale relative motion on the frictional behavior and the surface damage of a bearing steel were studied under dry condition. As a novel friction and wear testing method, a cyclic ring-on-ring test was conducted by making use of a hydraulic-controlled combined axial and torsional fatigue testing machine. The coefficient of kinetic friction was ranged from 0.4 to 1.0, the average value being about 0.75.

Shear strength tests of glass ceramic sealant for solid oxide fuel cells applications

Different approaches are used for the integration of ceramic components in solid oxide fuel cells stacks, where dissimilar materials (ceramics and metals) have to be joined and coupled for a reliable long term operation. This work focuses on the mechanical characterisation of a glass ceramic sealant used for the joining of Crofer22APU metallic interconnect samples as well as the interaction with a preoxidised Crofer22APU. Crofer22APU–glass ceramic sealant joined samples are tested by two different mechanical tests. Hourglass samples with different geometries were tested using an in-house developed torsion test machine at room temperature. In addition, their mechanical strength was also evaluated according to the ISO 13124 standard. The comparison of the two different testing methods, with particular focus on the shear strength of the joined samples, are reviewed and discussed.

Effect of Crosslinks on the Stability of the Spine and the Pedicle Screw Fixation.

To evaluate the effect of crosslinks on the stability of the spine and pedicle screws. Compression fracture of the L1 vertebra was produced in 30 fresh thoracic and lumbar vertebrae samples obtained from adult sheep, which were divided into 3 groups (n=10)with lot-drawing method. Four screws were fixed onto the superior and inferior pedicles of vertebral arch close to the fractured vertebrae, with different number of crosslinks (0 in Group A,1 in Group B, and 2 in Group C) on the rods. After fixation, the samples were subject to 10 000 times of fatigue test with 1.5 Hz load on the HY-3080 computer-control electronic universal test machine and HY-1000NM computer-control torsion test machine. The axial compressive stiffness, maximum pullout strength,and range of motion (ROM) of 6 directions, i.e., flexion, extension, left and right lateral bending, and left and right axial rotation of the 3 groups were measured and compared. There were no statistically significant differences in axial compressive stiffness as well as the ROM of flexion, extension, and left and right lateral bending (all P>0.05). The maximum pullout strength was significantly smaller in Group A and Group B than in Group C [(129.56±29.63)N vs.(294.67±23.25) N,P=0.000;(254.02±36.29)vs.(294.67±23.25)N, P=0.006]. The ROM of left axial rotation was the highest in Group A(13.35°±1.06°), followed by Group B(12.23°±1.06°)and Group C (11.04°±0.74°)(F=13.44, P=0.000; Group B vs. Group A, P=0.000; Group B vs. Group C, P=0.001; Group C vs. Group A,P=0.000). The ROM of right axial rotation was also the highest in Group A(13.56°±1.15°), lower in Group B (12.39°±1.01°) and the lowest in Group C (10.81°±0.51°) (F=21.91, P=0.000; Group B vs. Group A,P=0.002; Group B vs. Group C, P=0.001; Group C vs. Group A, P=0.000). Crosslinks may reinforce the pullout strength of the screws and improve the axial stability of the spine.

A differential electromagnetic induction torque sensor and its finite element analysis.

Torque is an important parameter for condition monitoring and fault diagnosis for rotary machines. This paper describes a new structure differential torque sensor based on the principle of electromagnetic induction. The method involves the construction of a pulsating flux by the excitation winding of the sensor, and the torsion angle produced by the load torque is converted into the angle displacements of the excitation winding and the output winding. Last, the output winding of sensor generates an induction potential force, which is proportional to the load torque as seen through electromagnetic coupling. Sensor sensitivity would be reduced by load effect; therefore, this paper presents a suppression method that can ensure the sensitivity is not affected. The transfer function of the sensor is constructed through Laplace transformation. The sensor characteristics are simulated by finite elements, including the influence of winding coil numbers and excitation voltage frequency. The sensor was calibrated by a torsion testing machine, and the experimental results indicated that the sensitivity of the sensor is about 18.2 mV/Nm, the non-repeatability error is about 2.3%, the non-linear error is about 3.3%, and the hysteresis error is about 2.6%.

Measurement of Twist Springback on AA6061-T6 Aluminum Alloy Strip - A Preliminary Result

Twist forming is one of a critical process in a sheet metal forming process that has a complex profile. There are a few parameters that need to be taken into consideration, such as twist angle, workpiece geometries including length, width and thickness and material properties of the workpiece material. In this study, the preliminary result of the twist forming behavior of an aluminum alloy strip with uniform section will be studied. The experiment is conducted using torsion test machine. At this stage, the torque pattern was studied and compared with the published work to validate the experiment test rig. The result showed an agreement with the published work.

Simulation and Test Study of Multidisc Magneto-Rheological Fluid Clutch

A Magneto-rheological Fluid Clutch (MRC for short) which has a novel and simple structure is designed; the research on the magnetic field distribution is based on the finite element simulation software which is named Ansoft; In order to test the work performance, the electronic torsion testing machine is used for the torque transmission capability and controllability test. The experimental results reveal that the MRC could meet the torque transmission demand of high power machine and response quickly and reliably.

Design of 80000N·m Torsion Testing Machine

The article introduce the mechanical structure and the principles of 80000 N·m torsion testing machine, the structure and the principles of checking power unit of this kind of testing machines and the control manner and the principles of the electronic control system, than expound the benefits of the equipment and its application.

EXPERIMENTAL INVESTIGATION ON TORSION BAR SUSPENSION SYSTEM USING E- GLASS FIBRE REINFORCED COMPOSITE MATERIAL

The purpose of this study is to investigate torsion deflections and energy storage of the composite bar in torsion bar suspension system. In this experimental study, round solid steel bar is machined and wounded with E-Glass/ Epoxy were manufactured by filament winding process. The experiment was carried out on a torsion test machine, which was built specifically to investigate the static and dynamic characteristics of torsion spring bar used in vehicle suspension system. This paper provides fundamental knowledge of torsion test and significant parameters such as torque, modulus of resilience in torsion and angle of twist has been highlighted. The torsion deflections were obtained experimentally. The results of experimental study are compared with the conventional torsion suspension system.

Fretting Fatigue Testing of Carburized Alloy Steel in Very High Cycle Regime Using an Ultrasonic Torsional Fatigue Testing Machine

Recently, high-strength alloy steels have been developed and used for various products. It is well known that fretting fatigue does not show fatigue limit. In other words, fretting fatigue failure may occur in very high cycle regime more than 107 cycles. However, it is difficult to investigate fretting fatigue property in very high cycle regime by using conventional fatigue testing machines because it is time-consuming. In this study, a fretting fatigue testing method for carburized alloy steels in very high cycle regime is explored by using an ultrasonic torsional fatigue testing machine. Carburized SCM420H was used for investigation. The experimental results showed that it is possible to conduct fretting fatigue testing of carburized alloy steels by using an ultrasonic torsional fatigue testing machine.

Biomechanical evaluation of fracture fixation constructs using a variable-angle locked periprosthetic femur plate system

BackgroundIn the United States there are more than 230,000 total hip replacements annually, and periprosthetic femoral fractures occur in 0.1–4.5% of those patients. The majority of these fractures occur at the tip of the stem (Vancouver type B1). The purpose of this study was to compare the biomechanically stability and strength of three fixation constructs and identify the most desirable construct. MethodsFifteen medium adult synthetic femurs were implanted with a hip prosthesis and were osteotomized in an oblique plane at the level of the implant tip to simulate a Vancouver type B1 periprosthetic fracture. Fractures were fixed with a non-contact bridging periprosthetic proximal femur plate (Zimmer Inc., Warsaw, IN). Three proximal fixation methods were used: Group 1, bicortical screws; Group 2, unicortical screws and one cerclage cable; and Group 3, three cerclage cables. Distally, all groups had bicortical screws. Biomechanical testing was performed using an axial–torsional testing machine in three different loading modalities (axial compression, lateral bending, and torsional/sagittal bending), next in axial cyclic loading to 10,000 cycles, again in the three loading modalities, and finally to failure in torsional/sagittal bending. ResultsGroup 1 had significantly greater load to failure and was significantly stiffer in torsional/sagittal bending than Groups 2 and 3. After cyclic loading, Group 2 had significantly greater axial stiffness than Groups 1 and 3. There was no difference between the three groups in lateral bending stiffness. The average energy absorbed during cyclic loading was significantly lower in Group 2 than in Groups 1 and 3. ConclusionsBicortical screw placement achieved the highest load to failure and the highest torsional/sagittal bending stiffness. Additional unicortical screws improved axial stiffness when using cable fixation. Lateral bending was not influenced by differences in proximal fixation. Clinical relevanceTo treat periprosthetic fractures, bicortical screw placement should be attempted to maximize load to failure and torsional/sagittal bending stiffness.

Creep strength of Mod.9Cr1Mo steel under biaxial stress states

This paper describes the development of tension, torsion, and combined tension-torsion creep testing machine with hydro static thrust bearing, criterion on creep rupture strength under biaxial stress states was examined. Tension, torsion, and combined tension-torsion creep tests were carried out at 873 K in air employing the developed creep testing machine and hollow cylindrical specimen of Mod.9Cr1Mo steel. Ratio of rupture time tR/tR* increased with the decreasing principal stress ratio λ at constant Mises' equivalent stress, where tR, and tR* denote rupture times for biaxial and tension creep tests, and λ expresses ratio of minimum principal stress to maximum principal stress. Hayhurst's stress successfully correlated with tension, torsion, and combined tension-torsion loading creep lives but Mises' type equivalent stress and maximum principal stress were inadequate to predict creep lives of Mod.9Cr1Mo steel. Oxide film and micro cracks on specimen surfaces were observed using SEM. Micro cracks and oxide film cracks initiated to the perpendicular direction to maximum principal stress axis for -1≦λ≦0. Main crack grew in direction perpendicular to specimen axis independent on the maximum stress ratio λ. The residual lives under biaxial stress states were estimated using Omega method. The Omega method was able to estimate the residual lives within a factor of 4 under biaxial stress states.

Extracortical plate fixation with new plate inserts and cerclage wires for the treatment of periprosthetic hip fractures

Fixation of periprosthetic hip fractures with intracortical anchorage might not be feasible in cases with bulky implants and/or poor bone stock. Rotational stability of new plate inserts with extracortical anchorage for cerclage fixation was measured and compared to the stability found using a standard technique in a biomechanical setup using a torsion testing machine. In a synthetic PUR bone model, transverse fractures were fixed distally using screws and proximally by wire cerclages attached to the plates using "new" (extracortical anchorage) or "standard" (intracortical anchorage) plate inserts. Time to fracture consolidation and complications were assessed in a consecutive series of 18 patients (18female; mean age 81years, range 55-92) with periprosthetic hip fractures (ten type B1, eight type C-Vancouver) treated with the new device between July 2003 and July 2010. The "new" device showed a higher rotational stability than the "standard" technique (p < 0.001). Fractures showed radiographic consolidation after 14 ± 5weeks (mean ± SD) postoperatively in patients. Revision surgery was necessary in four patients, unrelated to the new technique. In periprosthetic hip fractures in which fixation with intracortical anchorage using conventional means might be difficult due to bulky revision stems and/or poor bone stock, the new device may be an addition to the range of existing implants.