Grip End Research Articles

The Effect of Buckling Restraint on Axial Strain Life Fatigue Data

Abstract Focused on the common problem of easy specimen buckling in the axial strain–controlled fatigue testing of thin automobile steel sheets, a strain fatigue test method for thicknesses less than 2.5 mm is proposed. Because of the unrestrained grip end of specimens between the anti-buckling device and the testing machine fixture, specimens were prone to buckling in this area. In addition, if the designed specimen sizes were unreasonable, buckling may have occurred in the width and thickness directions of the gauge length of the specimen. Both situations can lead to invalid tests. This paper adopted a testing machine fixture and an anti-buckling plate as a mortise-and-tenon structure for the anti-buckling method; the upper and lower fixtures of the testing machine were cut in straight grooves, and the left and right anti-buckling plates were designed to be connected with a mortise and tenon. This is equivalent to narrowing the width of the unrestrained part of the specimen’s grip end to avoid buckling failure due to plane strain. The factors affecting the stiffness of fatigue specimens are also discussed herein. In order to avoid common instability in the thickness and width directions of the gauge length and unconstrained part of the specimen’s grip end at a strain ratio of Re = −1 during testing, six recommended specimen sizes are given on the premise of ensuring maximum specimen stiffness. When using the anti-buckling device, the recommended specimen sizes and test points of this study (i.e., the lower limits for yield strength and thickness of strain control testing) are 110 MPa and 0.5 mm, respectively, with which continuous and smooth stress–strain curves that result in accurate and reliable experimental data can be obtained.

Unusual step-like stress flow behavior and mechanisms of a 1.3 GPa grade medium-Mn steel with 51.2 % ductility

A Fe-8.9Mn-1.59Si-1.0Al-0.25C medium-Mn steel have achieved a superior combination of strength and ductility, i.e., the product of strength and elongation (PSE) of 66.5 GPa%. Meanwhile, an unusual step-like stress–strain curve due to heterogeneous deformation bands including Lüders band and multiple Portevin–Le Chatelier (PLC) bands was investigated systematacially. The repeated heterogeneous deformation is due to a combination of extrinsic and intrinsic factors. The former refers a small stress concentration near the grip ends of the tensile sample, and the latter is associated with low density of initial mobile dislocations, limited capacity of mobile dislocation multiplication and the presence of meta-stable austenite. As for meta-stable austenite, stress-assisted martensite transformation (SAMT) was confirmed experimentally, which will facilitate strain concentration and the starting of heterogeneous deformation. Moreover, before strain-induced martensite transformation (SIMT), it is the plastic deformation of austenite grains through the slip of partial dislocation and stacking faults (SFs) that contributes to a larger Lüders strain. Finally, we propose that whether it is possible to make the heterogeneous deformation to be a positive side for certain working conditions, which may open new doors for the application of medium-Mn steels. We will continue to do some exploratory studies in this direction next.

Analysis of a sandwiched piezoelectric semiconducting thermoelectric structure

In this paper, we analyze the piezo-thermoelectric responses of an integrated n-type piezoelectric semiconducting (PS) thermoelectric (TE) film and substrate membrane structure. Equations governing the behavior of the laminated PSTE structure are first derived based on the phenomenological theories of thermoelectricity and piezoelectric semiconductors. Closed form solutions of stress, deformation, electric displacement and electric field are obtained under a steady state thermal gradient and fixed grip end conditions. A parametric study for a zinc oxide (ZnO) PSTE film sandwiched between zirconia (ZrO2) substrate membranes show that both tensile and compressive stresses develop in the ZnO film and all field variables are dramatically influenced by the pyroelectric constant.

Development of Live Working Robot for Distribution Network

The distribution network is the key link to ensure the continuous power supply. The live working of the distribution network has become an important means to ensure the reliability of power supply and improve the reliability of power supply. This article designs a suitable application according to the task of live working of the distribution network and the analysis of the working objects. A live working robot which is used for distribution network with a voltage level of 10 kV or less. The robot is composed of a mobile insulation platform, a robot body, a working end, an insulation protection system, and a control system, where in the robot body includes a control box, a work robot, and a work tool transfer device. The end of the operation includes a grip end, a wire stripping end, and a clip mounting end. The results show that the robot can replace the manual task of charging and disconnecting wires, reduce the labor intensity of the operators and ensure the safety of the operators.

Implications of Rigid Gripping Constraints on Clubhead Dynamics in Steel Golf Shafts

Research and equipment testing with golf robots offers much greater control and manipulation of experimental variables compared to tests using human golfers. However, whilst it is acknowledged that the club gripping mechanism of a robot is dissimilar to that of a human, there appears to be no scientific findings on the effects of these gripping differences on the clubhead at ball impact. Theoretical and experimental strain propagation rates from the clubhead to the grip and back to the clubhead were determined during robot testing with a 9-iron to determine if this time interval was sufficiently short to permit the gripping mechanism to have an effect on the clubhead during impact. Longitudinal strain appears to propagate the most quickly, but such deflections are likely to be small and therefore of little meaningful consequence. Shaft bending was not a primary concern as modes of large enough amplitude appear to propagate too slowly to be relevant. Torsional strain propagates at a rate which suggests that constraints at the grip end of a golf club could potentially influence impact dynamics for steel shafted irons; however, this effect seems unlikely to be significant, a likelihood that decreases further for longer irons. As such, it is considered reasonable to treat the influence of a robot’s gripping mechanism on clubhead dynamics at impact as negligible, and therefore comparisons between robot and human data in this regard are valid.

A Novel Hybrid Heating Method for Mechanical Testing of Miniature Specimens at Elevated Temperature

A novel hybrid heating method which combines the conventional electric-resistance specimen heating with microcoil heating of specimen ends to achieve uniform heating over the gauge length is presented. Resistive heating of a miniature specimen develops a parabolic temperature profile with lowest temperature at the grip ends because of the heat loss to the gripper. Coil heating at the specimen ends compensates for this heat loss resulting in uniform temperature distribution over the central segment of the specimen. Thermo-electric finite element simulations were carried out to analyze the transient and steady temperature distribution in miniature specimens followed by experimental validation.

Measurement of Angular Motion in Golf Swing by a Local Sensor at the Grip End of a Golf Club

This paper describes a novel method for measuring golf swing angular motion in a global coordinate system using the 3-D acceleration and angular velocity detected by a local motion sensor set at the grip end of a golf club. Optical direct linear transformation (DLT) is the conventional method for measuring sports motion; however, accurate localization of global coordinates and precise setting of infrared high-speed cameras in the test field are essential. Furthermore, infrared reflectors must be attached to the moving object. The system itself and the fine-tuning are expensive, but an accurately set system can provide precise positions for the moving reflectors. It is effective for measuring translational motion but not angular motion that is based on the principles of measurement. The alternative method that is proposed here is easier in terms of setting and fine-tuning, more reasonable in cost, and more accurate in measuring rotational motion compared with the DLT method. Furthermore, the system's wireless transmitter enables noninvasive measurement. When addressing the golf club, its initial angles and posture matrix are calculated using the 3-D acceleration; when the swing begins, the motion sensor measures the changing angular velocity and the acceleration. The application of step-by-step Euler transformation for each sampling interval yields the angular velocity and angle in the global coordinate system. The mean RMSE of ten trials with five subjects was 3.06°, 26.64°, and 4.43° for the 3-D angle of the club shaft.

J232011 パッティングストロークにおけるクラブヘッドの三次元運動計測([J232-01]ヒューマンダイナミクス(1))

This study describes a method for measurement of the golfs putting stroke. The data obtained can be available for sports skills assessment and training. Measurement method proposed was derived by kinematical human body model analysis. The system was developed using 3-D gyro sensor and infrared sensor. Gyro sensor was used to measure the rotation of the club head. Moreover, infrared sensor was used to measure the distance changes between the grip end and the body during putting stroke. As a result of the experiment, the following matter became clear. (1) During swing, since the distance of grip end and body of subjects is changing, it cannot be said that putting stroke is a simple pendulum easily. (2) The golf middle-class player swung so that the face side of a head might become perpendicular to the direction of a hit ball.

312 試作したホッケースティックモデルの打撃性能について(生体衝撃負荷)

The top players of field hokey experientially know that high restitution area of their hokey stick exists not on the head but on the position slightly shifted to grip end. They would have to swing the stick horizontally with low posture to hit the ball near the area when strong and high speed balls were needed in the game. Therefore, we have been developing a new hockey stick that has high restitution area on the head. The mass distributions of sticks affect the positions of the 1st modal node of vibration and center of percussion has been found. The area on the high coefficient of restitution may be related to the positions of the 1st modal node of vibration and center of percussion. In this study some experiment using sticks with the various positions of the modal node and the center of percussion controlled by the mass distributions has been carried out. Furthermore a hockey ball model was newly proposed for FEM analysis. The results of the FEM simulation closed on the results of our previous experiment.

Novel method of the double-loop slip-knot: preknotting on the laparoscopic forceps enables easy and secure intracorporeal ligation

Laparoscopic ligation is a difficult and advanced technique because of the limited movement of forceps under two-dimensional videoscopic view. Currently, single-port surgery is widely used and a simple method for intracorporeal ligation is required. We describe an intracorporeal slip-knot with a double-loop strand that can be used to provide security and present the experimental results obtained. A modified Eskimo bowline with a 4-0 absorbable monofilament was placed on a needle driver, and the forceps was used to grip both ends of the thread. Another forceps was used to pass the line under vessels in the abdominal cavity. The line was withdrawn from the gripping point through the preknot on the rod after it was gripped at the same point. The slip-knot was tightened, and a pushing forceps and a needle driver were used to push the knot and complete the ligation. The double-loop slip-knot has a high bursting pressure compatible with that of a conventional square-to-slip knot, which is significantly higher than that of any other slip-knot. In an experimental evaluation on animal laparoscopy, residents performed complete ligations of gastric and colonic arteries and veins within 30 s after a short explanation of the procedure. This novel slip-knot with a double-strand loop could provide easy and secure intracorporeal ligation. This type of slip-knot has great potential for wide use in open surgery using laparoscopy. Further evaluation is required to determine its clinical applicability.

Understanding the mechanisms of shaft deflection in the golf swing

An understanding of shaft dynamics during the golf swing was gained through a series of theoretical simulations, using a 3D forward dynamics model. By resolving the resultant force applied at the grip end of the club into a tangential and a radial (centripetal) component, the mechanisms of shaft deflection were quantified. It was determined that radial force plays an important role in producing the toe-down and lead-deflections recorded in all golf swings made with a driver. However, the simulations also revealed that the recoil of the shaft, from its previously toe-up and lag deflected position during the downswing (due to tangential forces), plays at least an equally important role in determining the position and orientation of the clubhead at impact. It was further demonstrated that, due to the influence of the radial force component, maximum kick velocity is reached after the clubhead has passed beyond the neutral shaft position.

A-45 フリーバッティングにおけるバットの角速度と打球飛距離(野球4(打撃))

The purpose of this study was to characterize the bat swing parameters that increase the flight distance. Thirteen members of a collegiate baseball team performed free-batting practice. The batting performances were recorded with a ultra-high-speed camera and a tri-axial gyro-sensor attached to the grip end of a wooden baseball bat. Flight distance had a high correlation with the kinetic energy possessed by the batted ball (p<0.01) which, in turn, was correlated with the rolling velocity of the bat (p<0.05), the direction of the bat swing (p<0.01) immediately before the impact (p<0.05) and the orientation of the line of impact (p<0.05).

Creep testing standards and the influence of bending

Few data appear to be available quantifying the relationship between bending, or off-axis loading, and the high temperature creep properties of industrially important alloys. This paper reviews the literature on the topic and also presents some new experimental evidence showing the influence of bending on the creep properties of IN939 at 850°C.In general, for materials with reasonable ductility i.e. >3%, the amount of bending likely to be encountered due to normal machining tolerances on the testpiece grip ends and loading bar adaptors is not sufficient to cause a significant change in the expected creep life in comparison with the normal scatter attributable to the other testing tolerances e.g. temperature and load.This paper will help address the plea incorporated into the newly revised creep Standard ISO 204 requesting data correlating creep and bending that could provide information for inclusion into a statement of measurement uncertainty.

Shifting a portion of the clubshaft’s mass distally: does it improve performance?

The purpose of this paper was to examine the claim, based on a pendular swing demonstration, that moving a portion of the mass from the grip end of a golf club to a position further down the clubshaft improves clubhead speed at impact. A twodimensional model of a golf club was used to simulate the pendulum swing demonstration provided by a company that purportedly showed that such an optimal shifting of the club’s mass increased the velocity of the clubhead at impact. Two sets of simulation experiments were performed. The first supported the video demonstration provided by the company, which showed that a club’s swing-speed, while swinging under only the influence of gravitational torque, could be increased by relocating a portion of the club’s mass further down the shaft. However, in the second set of experiments when an externally generated torque was applied to the grip end of the club, as would be the case for the uncocking of the wrists during the later stage of the downward swing, the relocation of mass further down the shaft proved to have a detrimental effect on the generation of clubhead speed leading up to impact. Thus, a pendulum swing, which uses only gravitational torque to drive the system, is an inappropriate test for evaluating the benefits of club design modifications intended to improve clubhead speed at impact.

Wireless MEMS inertial sensor system for golf swing dynamics

The emergence of accurate MEMS inertial sensors motivates the design of miniature inertial measurement units (IMU) for applications well outside the field of inertial navigation. One promising application concerns novel sports training systems with inertial sensors embedded directly in sports equipment. This paper describes the theory, design, and evaluation of a miniature, wireless IMU that precisely measures the dynamics of a golf club used in putting. The design consists of a complete six degree-of-freedom IMU composed of MEMS accelerometers and angular rate gyros with an integrated microprocessor and RF transceiver. The resulting sensor system has negligible mass (25 g relative to 490 g for the putter) and is a mere 13 mm in diameter allowing it to fit wholly within the shaft of the club at the grip end. The measurement theory enables the computation of the position, velocity, and orientation of the club head at the opposite end of the shaft during the entire putting stroke. Experiments reveal that the three-dimensional position and orientation of the club head can be resolved to within 3 mm and 0.5°, respectively. These achievements yield a highly accurate, portable, and inexpensive sensor system to support golf swing training, custom club fitting, and club design.

Fatigue Properties of Surface-Micromachined Al-3%Ti Thin Films

This paper describes new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a fatigue test. High cycle fatigue test has been performed on tensile type specimen of Al-3%Ti alloy using the newly developed fatigue test machine. The material used in this study was Al-3%Ti thin film, which was used in RF MEMS switch. The structure of the suggested specimen has two holes and several bridges. The holes at centre of grip end are able to make alignment and gripping easy. The bridges are to remove the side support strip easily and extract specimen from wafer without sawing. The test machine was developed using the voice coil of speaker. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. Fatigue tests was performed on 7 specimens. The thickness and width of the thin film of specimen are 1.0μm and 150μm, respectively. The fatigue strength coefficient and the fatigue strength exponent of Al-3%Ti alloy micro-sized specimen are determined to be 164MPa and -0.01322, respectively

Size Effect on Tensile Strength of Surface-Micromachined Al-3%Ti Thin Films

A new tensile tester using an electromagnetic-force actuator (voice coil) was developed to measure the mechanical characteristics of surface-micromachined thin film materials. The tester has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. The tester was applied for tensile testing of Al-3%Ti thin films with dimensions of 1000μm long, 50-480μm wide and 1.0 and 1.1 μm thick. The Al-3%Ti is commonly used in RF(radio frequency) microelectromechanical systems(MEMS) switch. The specimen with holes and bridges was designed for easy tensile test. The holes at center of grip end are able to make alignment and gripping easy. The bridges are to remove the side supports easily and extract specimen from wafer without sawing. It was found that the mean tensile strengths of Al-3%Ti are 140-380MPa, depending on the width of specimens and converging to a certain tensile strength as the width decreases.

Novel Test Procedure of Tensile Test for MEMS Materials

This paper describes a novel test procedure, new structure of specimen easy to manipulate, align and grip a thin-film and test machine for a tensile and fatigue test. For the proposed specimen, the surroundings of the specimen including the side support strips except for six bridges are etched during the fabrication of the specimen, which in turn makes it possible to cut off easily the specimen from the wafer by minimizing a damage to the test film and also possible to produce the specimen in mass production. For the present specimen, a small hole is made at the grip end and using a small pin for setting the specimen onto the tester, the setting process and alignment of specimen is much easier, compared to the specimen proposed by Sharpe et al. To gain confidence in reliability of testing results, pre-test using the Al-3%Ti is performed, which is widely used in the RF switch and other MEMS devices. Tensile tests are performed, from which tensile strengths of the Al-3%Ti are measured as 343±16.22MPa at 200μm width and 1.1μm thickness.

Mechanical properties of Au thin film for application in MEMS/NENS using microtensile test

Abstract In the case of MEMS and NEMS, the mechanical properties of their materials are closely related to their performance and reliability. The measurement of the mechanical properties of thin film for MEMS/NEMS is difficult because of the small sizes, forces, and displacements involved as well as the need for special techniques to prepare and handle the specimens. In general, micromechanical tests involve three main issues; specimen preparation, force application and measurement, and displacement or strain measurement. The microtensile testing system was developed. The grip ends of the specimen are glued to the grips attached to a piezoelectrically actuated loading system. Strain is measured directly on the specimen with laser interferometry named ISDG. Au is one of most widely used materials in microelectromechanical systems. Au film in the pattern is deposited on Si substrate by sputtering process, of which thickness is 1 μm. For strain measurement the markers on the specimen was made by focused ion beam (FIB). Using the microtensile test, stress–strain curve, elastic modulus and ultimate tensile strength of Au thin film was obtained. The results were compared with those of nanoindentation test.

Mechanical Properties of Al-3%Ti Thin Film for Reliability Analysis of RF MEMS Switch

This paper presents a novel experimental method to investigate the strength of material, Al-3%Ti, which is commonly used in RF(radio frequency) microelectromechanical systems(MEMS) switch. The experimental method involves the development of a new tensile loading system. The new tensile loading system has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry with 0.1nm resolution for displacement measurement. A voice coil of audio speaker is used as the actuator of the loading system. And new specimen was designed and fabricated to easily manipulate, align and grip a thin-film for a tensile and fatigue test. The material used in this study was Al-3%Ti thin film, which was used in RF switch. The thickness and width of the thin film of specimen are 1.1µm and 480µm, respectively. The holes at center of grip end are able to make alignment and gripping easy. The bridges are to remove the side supports easily and extract specimen from wafer without sawing. Tensile tests were performed on 5 specimens. The ultimate strength of Al-3%Ti was 144MPa.