Type Testing Machine Research Articles

Impact load transmission of the knee joint-influence of leg alignment and the role of meniscus and articular cartilage

Objective. The objective of this study was to evaluate load transmission in the cancellous bone of the tibia under static and impact load. Background. Abnormal transmission of loads may result in osteoarthritis and fractures. However, the role of the cancellous bone in these processes is not well understood. Methods. The compressive stresses in the subchondral bone, epiphysis and diaphysis of the tibia of porcine knees were measured under static and impact load using mini-pressure transducers. The tests were performed using a drop-tower type testing machine in neutral, varus and valgus alignments. Tests were repeated after meniscectomy and again after removing the articular cartilage. Results. In the intact knee in all alignments, the highest stress on the medial side was found in the epiphysis, and in the subchondral bone on the lateral side. After meniscectomy, a significant increase was observed in the stress in the subchondral bone on both sides. After the articular cartilage was also removed, the stress in the subchondral bone increased again, but slightly. Conclusion. The importance of the meniscus in load transmission is supported by this study. The contribution of the articular cartilage to load transmission is less than that of the meniscus. Relevance. The patterns of static and dynamic load transmission observed in this study correlate with the sites of insufficiency fractures of the medial tibial plateau and traumatic lateral tibial plateau fractures observed clinically. Examination of the load transmission is key to a more complete understanding of the causes of osteoarthritis and tibial plateau fractures.

Effects of the Number of Siping Edges in a Tire Tread Block on Friction Property and Contact With an Icy Road

Abstract Friction coefficients between tires and an icy road were measured at various temperatures and slip velocities using an inside-drum type testing machine. The tire contact with the icy road was observed during sliding. Effects of the number of sipes in a tread blocks on the friction coefficient were examined.

Engagement behaviour of a paper-based wet clutch Part 1: Influence of drive torque

Owing to increasing demands when designing wet clutches for automatic transmissions, more knowledge about their behaviour is needed. In cars with power shifting automatic transmissions, an engine torque is continuously transmitted through the gear box. Most experimental and theoretical work concerning investigations of wet clutches today uses the inertia type of test apparatus, e.g. the SAE test machine 2. However, this type of test machine has no possibility of investigating the influence of a drive torque from the power supply. In order to investigate the influence of drive torque on wet clutch engagements, a new type of apparatus was built, which can operate with different combinations of inertia and drive torque. This apparatus can perform engagements more similar to those in automatic transmissions. The aim of this paper was to compare experimental outputs obtained using these principles of testing, concerning the influence of drive torque. It was found that the friction characteristics of wet clutches are independent of how the input energy is produced. This means that friction can be investigated with both principles. It was also found that an apparatus using only inertia gives shorter engagement times and higher temperatures than an apparatus including a drive torque at the same level of input energy. This can be explained by different power characteristics. Therefore, when investigating temperatures of wet clutch engagements, one must be careful when translating the results into reality.

An experimental study of a combination method using a pedicle screw and laminar hook for the osteoporotic spine.

Using human cadaver spines, the authors compared the effect of using a combination of pedicle screw and laminar hook on the same vertebra with that of using a pedicle screw alone in reference to bone mineral density of the vertebra under nondestructive cyclic loading. To quantify stiffness obtained by pedicle screw alone and by the combination method and to clarify a relationship between stiffness obtained by each instrumentation method and bone mineral density of the vertebra. The use of pedicle screws apparently improves the union rate of spinal fusion. Instrumentation failures sometimes occur, however, such as loosening or loss of correction of the spine, especially in patients with osteoporosis. Some augmentation method in instrumentation is necessary to overcome bone fragility in the osteoporotic spine. Thirteen cadaver lumbar vertebrae were used for this study. Bone mineral density was measured by dual-energy X-ray absorptiometer. After separating each vertebrae, the pedicle screw was screwed into a vertebra. Five cycles of cephalocaudal loading were performed to the shank of the screw with a cross-head speed of 3 mm/min under a maximum load control of 29.4 N using an Instron type testing machine, and the stiffness obtained with the pedicle screw (Kj) was calculated from the load-deformation curve. Then, a laminar hook was set and connected to the screw via a rod. Mechanical testing was performed in the same way, and the stiffness obtained with the combination method (Kf) was determined. Kj and Kf were compared using the paired t test. The relationship between Kj, Kf, or the stiffness improvement ratio ([Kf-Kj]/Kj) by the combination method and bone mineral density was analyzed by linear regression analysis. Stiffness obtained by the combination method was significantly greater than that obtained by pedicle screw alone (89.8 +/- 35.0 N/mm by the combination method, 60.2 +/- 19.6 N/mm by pedicle screwing alone; P < 0.0001). Stiffness, whether obtained by pedicle screw alone or by the combination method, was positively correlated with bone mineral density (with pedicle screw alone, R2 = 0.614, P < 0.0001; with the combination method, R2 = 0.645, P < 0.0001). However, there was no significant correlation between stiffness improvement ratio and bone mineral density. Instrumentation stiffness obtained by the combination method was significantly greater than that obtained by the use of pedicle screw alone. There was no significant correlation between the improvement ratio by the combination method and bone mineral density. These results suggest that the combination method is valuable irrespective of the presence of spinal osteoporosis.

セラミックス成形体の被削性に関する研究（第３報）‐切削モデルの検討

In recent years, many ceramics have been to developed for the uses. Some ceramics for mechanical or electronic parts are required to be cut as the green compact. The cutting of the green compact is decreased cracks on the machined surface. The purpose of the paper is to clarify the mechanism at cutting of green compact. The cutting mechanism is investigated and discussed from the results of the fracture test by a new type testing machine and of the cutting test by a lathe. In the cutting test, the radius of cutting edge were varied from 0.8mm to 4mm. A fracture model is proposed from AE(Acoustic Emission) signal caused by fracture and SEM image of fracture surface. The main results obtained are as follows; (1) AE signal shows there stages of fracturing the green compact. (2) The fracture energy is from 4 J/m2 to 7 J/m2. (3) A fracture model is available to clarify the cutting mechanism. (4) The tool with large side cutting edge angle is able to cut a work at high efficiency and to elongate the tool life.

Biomechanical Study of Artificial Hip Joint.

To study the in vivo damage of the polyethylene acetabular cup retrieved at revision surgery was investigated, Mechanical properties were measured by a viscoelastic spectrometer and a universal Instron type testing machine with a torque meter. The following results were obtained ; 1) There was a positive quadratic correlation between stiffness of the acetabular cup and the duration from the implantation until the revision surgery in the case of the Weber type artificial hip joint. 2) There was a negative qudratic correlation between tan δ and the duration from the implantation until the revision surgery in the case of the Weber type artificial hip joint. 3) There was positive correlation between stiffness of the acetabular cup and the duration from the implantation until the revision surgery in the case of the Kyocera type artificial hip joint. 4) There was a negative correlation between tan δ and the duration from the implantation until the revision surgery in the case of the Kyocera type artificial hip joint. 5) There was a positive correlation between linear wear and the duration from the implantation until the revision surgery in the case of both the Weber and the Kyocera type artificial hip joints. 6) There was a positive correlation between torque and the duration from the implantation until the revision surgery in the case of both the Weber and Kyocera type artificial hip joints.

研削切断用薄手砥石の結合度試験

Bonding test of thin grinding wheels has been performed, using bit type testing machine. Bit displacement and torque were inversely proportional to the bonding grade of wheels, and were more closely connected with the bond contents. The torque needed to pulling out a grain was obtained as a function of the amount of bond contents per one grain. It was found that, the higher the bonding grade wheel, grains were more breakable than the lower one.

Influences of skidding pattern upon the occurrences of skid damage to railway wheels

Wheel skidding happens easily on braking when moisture and contaminants remain on the railhead. Then wheel-flat damage is liable to occur. This study was carried out to search for an appropriate skidding pattern by which the wheel flat would be reproduced experimentally. A two-roller type of testing machine, which suitably incorporates a skidding device, was designed and manufactured for the test. The device can give rise to wheel skidding either by the lubricant feeding to the contact zone of wheel and rail or by the application of the brake to the wheel specimen axle. Various patterns of wheel skidding are generated depending upon the lubricant, contact stress, skidding time and the brake operation. It is necessary for the wheel-flat reproduction to arrange a skidding condition in which severe wear is suppressed and the temperature of the skidding surfaces rises gradually. Stoppage of the wheel specimen is a useful technique to reproduce various degrees of flat damage.

Study on Tribology of Silicon Nitride Ceramic Tappet

In order to elucidate the tribological behavior of the Si3N4 ceramic used in automobile engine, a series of tests was carried out to measure the friction coefficient and wear resistance of Si3N4 during lubricated sliding against metals. A Timken type test machine and a spring loaded wear test machine were used for this study. Tests were also conducted with metal against metal pairs for comparison. The simulation tests of hot-pressed Si3N4 Ceramic tappet against metal cam pairs were conducted on a single cam-follower test machine. The test results showed that not only that the Si3N4 ceramic has excellent wear resistance, but also that the wear of the metal parts in contact with the Si3N4 ceramic decreased. These results were supported by engine bench test results.

The Tribological Reaction Accompanying Friction and Wear of Silicon Nitride Containing Titanium Nitride

Effect of humidity in atmosphere gas, air, or argon, is investigated for the tribochemical reaction in Si3N4 – 23 percent TiN-Si3N4 – 23 percent TiN sliding contact system using a pin-on-plate type testing machine by reciprocal movement of pin against plate. An examination is also conducted on Si3N4 – Si3N4 couple in comparison with the above system. The experimental results have shown that the wear rate decreases with increasing humidity, and the wear property is somewhat improved by adding a suitable amount of TiN to Si3N4. Reaction products formed on the interface under the sliding contact are analysed by using EPMA and XPS. It is confirmed that SiO2 (or TiO2) is produced on the surface during friction and wear, and the amount of SiO2 (or TiO2) increases with the increase of humidity. Formation of NH3 caused by development of tribochemical reaction on friction surface is examined by a spectrometric study using Nessler’s reagent. The results show that the formation of NH3 is connected directly with the amount of SiO2 (or TiO2), and that three types of formation rate are observed depending on the humidity.

Friction and wear behavior of graphite fiber‐reinforced composites

AbstractFriction and wear behavior of continuous graphite fiber composites was studied for different fiber orientations against the sliding direction. The effect of fiber orientation on friction and wear of the composite and on deformation of the counterface was investigated experimentally. A pin on disk type testing machine was built and employed to generate friction and wear data. A graphite fiber composite plate was produced by the bleeder ply molding in an autoclave and machined into rectangular pin specimens with specific fiber orientations, i.e., normal, transverse, and longitudinal directions. Three different wear conditions were employed for two different periods of time, 24 and 48 hours. The wear track of the worn specimens and the metal counterface was examined and a scanning electron microscope (SEM) to observe the damaged fibers on the sliding surface of the specimen and wear film generation on the counterface. A wear mechanism of the continuous graphite fiber composite during sliding wear is proposed based on the experimental results.

Development of a deflection controlled multiaxial fatigue testing machine

This paper discusses the development of a multiaxial fatigue testig machine. The deflection controlled eccentric disk type testing machine produces mode I, mode II, or combination of both, of crack surface displacements on round or flat specimens. These loadings are necessary for research on complex multiaxial stresses which are common in engineering practice, such as crankshafts. This machine achieved the objective with very simple mechanisms (vector sum of two crank throws of eccentric disks yield bending moments; vector differences, twisting moments), but with more computation in setting the desired parameters. Bending data and torsion data produced by the machine were in good agreement with the data by a conventional fatigue testing machine. Multiaxial data produced by the machine were also in good agreement with the prediction by a well proved multiaxial fatigue theory. Applications of the multiaxial fatigue testing machine are described.

Constitutive relations between stress, strain-rate and temperature of copper.

Strain-rate and temperature dependence on the flow stress of OFHC copper is discussed. Tensile tests were made ranging in strain-rate from 2.5 × 10-4 s-1 to 1 s-1 and temperature from 25°C to 600°C with a cam-plastometer type testing machine built as a trial. Experimental results were compared with a theory proposed previously by the first author for constitutive relationships of elastic/visco-plastic materials. On the temperature and strain-rate range discussed in this paper, it was recognized that three fields of deformation mechanism exist. The proposed equation represented well constitutive relation in individual field and correlation of neighboring fields. Significant variations of final reduction in area and total elongation also were discussed in connection with transition of deformation mechanism.

Friction and wear of nitrogen implanted aluminum alloy based FRM

Aluminum alloy based FRM (Fiber Reinforced Metal) has been implanted with nitrogen ions in order to investigate the effects of implantation on the tribological properties of the FRM. An SiC whisker reinforced aluminum alloy has been chosen as the specimen. The non-mass-analyzed nitrogen ions were implanted up to 10 18 |N/cm 2 at 90 kV using a Z-100 implanter. The friction and wear tests were made using a wheel on plate type testing machine at various friction loads. Appreciable improvements in friction and wear properties are revealed in an oil lubrication condition. The nitrogen implantation suppresses the adhesive wear between the FRM specimen and the stainless steel wheel.

窒素イオン注入によるＳｉＣウイスカー強化Ａｌ合金の表層改質

SiC whisker reinforced alminum alloys were implanted with N+ ions to investigate the effect of implantation on the tribological properties. N+ ion was implanted to 1018 ions/cm2 at 90keV. Wear tests was made using a pin-on-plate type testing machine at various loads. Appreciable improvements in wear properties were observed.

PREDICTION AND EVALUATION OF LONG‐TERM CREEP‐FATIGUE LIFE

AbstractOrdinary short‐term creep fatigue tests were carried out on a servo‐hydraulic testing machine for various heat resistant steels. From these results a life prediction method in the long‐term creep‐fatigue regime is proposed using creep rupture ductility data up to 105 h. To verify the predicted life the authors have developed a new type of testing machine driven by thermo‐actuator which can evaluate the long‐term creep‐fatigue behaviour of materials beyond 104 h.

黒鉛材料の遅れ破壊の機構に関する一考察

A mechanism of delayed fracture under static load was proposed for fine grained nuclear grade isotropic graphite.Rectangular specimens were loaded in 3-point bending mode to the neighbourhood of the fracture stress and kept at about the same stress level by using an Instron type testing machine. The discrete acoustic emission (AE) signals were generated before the specimen completely fractured. This fact indicates that microcracks are produced or propagate discontinuously within the specimen under static load. This phenomenon was explained by a model in which the microstructure of graphite is regarded as the combination of elastic and plastic parts. According to the model, the stress relaxation in the plastic part induces an increase in stress at the region of crack tips or some kinds of defects in the elastic part.

A Tabular Summary of Some Experiments in Dynamic Plasticity

A tabular summary of some experiments in dynamic plasticity is presented. The experimental work is divided into three categories according to the type of testing machine used. The results of investigations using the cam-plastometer, experimental drop forges, and split Hopkinson pressure bars are presented. In addition, a number of other methods for obtaining dynamic mechanical properties are discussed.

クレイズ発生と成長の統計的研究

In spite of many works on the initiation and growth of crazes, few studies on plastic deformation caused by crazing inherent in high polymer solids have been performed. In this paper, as the first step to describe plastic deformation in high polymer quantitatively, the craze density, i.e., the number of crazes per unit surface area, and the craze growth rate were investigated, and their statistical nature were examined.The experiments were performed under the action of a crazing agent, kerosene, at room temperature (20±1°C) with a constant load type testing machine on the specimens of polycarbonate and polyvinylchloride. The dependences of craze initiation and growth on applied stress and testing time were determined by photographs taken through an optical microscope without stopping the test.The main results were: (1) the variation of craze density with time can be described successfully by a simple rate theory, (2) the distribution of the craze growth rate, which has essentially a statistical nature, is approximated by a normal distribution function and (3) the dispersion of craze length at a certain time can be explained by a statistical theory which takes into account both the distribution function of growth rate and the density variation of crazes with time.

Friction Transients (Their Role in Friction Failures)

It is usually assumed that friction failures are due to excessive working conditions expressed as load, velocity, temperature and lubrication, or any combination of these. The failure criteria takes the form of “Flash Temperature,” “PV,” “PVT,” etc. By far more dangerous are the “Friction Transients” when the system passes from one steady state to another, both of them being quite safe. The experimental results confirm the theoretical expectations and lead to a new failure criterion expressing the rate of change of the local conditions produced by any of the disturbing variations while reaching the final steady state. In order to study the role of various operating variables on the transient friction instability, a new type of testing machine has been conceived. Presented at the JSLE/ASLE International Lubrication Conference in Tokyo, Japan, June 9–11, 1975.