−Application of AE signals with Wavelt transform−:
The non-destructive inspection that evaluates degradation condition of the structure member part is important in order to previously prevent the destruction of the structure. In one of this non-destructive examinations, there is MAE method for the elastic wave which arises by magnetization process of ferromagnetic material, and it is noticed as an evaluation method which very sensitively reacts for microscopic structural change of the material inside and change of stress state. However, the establishment of the non-destructive testing which utilized this technique has been retarded, because the generation mechanism of MAE has not sufficiently been clarified. In this study, MAE signals of pure iron and S25C that deformed plastically by tensile stress were measured with Displacement sensor (for the longitudinal wave detection) and Shear sensor (for the transversal wave detection). After then, wavelet transform that is possible to respect the time-frequency analysis of the detection signals, and the generation mechanism of MAE was examined.
Key Words : Non-destructive testing, Magnetomechanical acoustic emission, Wavelt transform, Displacement sensor, Shear sensor
Evaluation of Fracture Characteristics of TiN Ceramics Film Using Acoustic Emission
− Prediction of Scratch Mark with Scratch Testing −:
The demand for the materials of the structure member parts is severe, and ceramic coating material is getting the excellent performance in mechanical industry field because it shows characteristics of heat-resistance and abrasion resistance. However, the delay of the establishment for the evaluation method on the adhesion between mechanical strength of a film and parent material becomes an important problem in the development of the coating material. In this study, scratch testing was employed, AE method was utilized for detecting the signals of elastic wave, wavelet transform was used for analyzing the detected signals, and image processing was applied for picking up the character of the scratch mark. The evaluation method was proposed by using the above method, and the validity of this method was checked with the experimental results.
Key Words : Fracture characteristics, TiN ceramics film, Acoustic emission, Scratch testing, Scratch mark, Evaluation, Image processing, Fractal, Fuzzy
Evaluation on Behavior of Thermal Shock Fracture of TiN Ceramics Film with AE Method:
Ceramic coating materials that demonstrate the excellent characteristics are noticed, because the structure member parts are used in the severe environmental conditions. However, the ceramics that are the brittle material become a problem in which the evaluation on the thermal shock resistance is very important in the coating material, because it is comparatively easily destroyed by the repetition of the thermal fluctuation. In this study, the repeated thermal shock by YAG laser was given to TiN film, and the image processing was used for a grasp of the microscopic breakdown behavior. The detected AE signals at this time were applied for the quantitative evaluation of the damage part. Based on the data collected by this experiment, the system that evaluates damage conditions by one laser irradiation from the feature of the AE signal was constructed, and the effectiveness was examined.
Key Words : Evaluation, Thermal shock fracture, TiN ceramics film, Acoustic emission, Image processing, Fractal, Neural network
Detection of Crack Growth with Infrared Thermography：
The industrial machinery such as the high-temperature plant does not be used at fixed load and temperature, and there are many cases in which the load and temperature of its structural member parts fluctuate. In the equipment that receives temperature fluctuation, the thermal stress is generated, and the thermal fatigue crack may be generated. Therefore, defects such as the crack by thermal fatigue occur in surface and inside of material. It is very important to detect such defects in security and quality maintenance. Recently, the infrared thermography method is noticed in the detection method of such crack. The character of the method is non-contacting, non-destruction and it is very effective in order to catch detection of the crack and the fracture phenomenon in the thermal fatigue. In this study, our aim is to evaluate the generation of the crack from the temperature distribution condition that arises by the thermal fatigue process.
Key Words : Thermography, Acoustic emission, Crack growth, Detection
Grasp and Evaluation of Wear Types with AE：
Though the lubricant is used for the slide division of the machine, the abrasion is generated at the contact zone, when lubricated condition becomes bad. Vibrations and noise, etc. are generated, when the abrasion is generated. As the results, they may come to the destruction. Therefore, it is important to predict the transition of future phenomenon from the detected information. And, it is important industrially to recognize the abrasion phenomenon in the inprocess. From above mentions, AE methods that process the elastic wave that is caused by plastic deformation or destruction are center of attention. In this study, AE parameter and frequency components of AE signal were examined by researching the correspondence between abrasion condition and AE signal.
Key Words : Waer, Acoustic emission, Evaluation, Wavelet transform
Evaluation of Fatigue Damage with AE：
With the diversification of the function for machine and structure, various industrial materials are used according to the application. The fatigue occupies many on the fracture case of the structure in such situation. Therefore, it is a very important problem to establish the soundness evaluation method of the structural member parts. And it becomes important that the problem on fatigue strength and fatigue crack progress characteristics is considered. From such fact, there are many study cases that applied the AE method. However, there is a serious problem that is discrimination of AE signal that originates from the crack propagation and the friction between crack planes, when fatigue damage by the cyclic fatigue process was evaluated by AE method. In this study, wavelet transform was applied for solving the problem, and the validity was examined.
Key Words : Fatigue, Acoustic emission, Evaluation, Crack growth, Crack closing
Behavior of Residual Stress and Texture in Drawinig of the Steel Wire:
Two kinds of drawing processes, the unidirectional drawing and reverse re-drawing, were applied to the drawing of two kinds of steel wire rods called S35C and SWRCH6R. Then the residual stresses of the steel wire rod drawn by the two kinds of drawhg processes were measured. The surface residual stresses to the axial direction of the steel wire rod were measured using X-ray analysis method. The result shows that there was a clear difference in residual stresses between unidirectional drawing and reverse re-drawing at nearly the total reduction 28 %. But beyond the total reduction 62 %, there was little difference in residual stresses. In addition, the texture of the steel wire rod was observed usirig measuring method called Schulz reflection method which is one of the X-ray analysis methods.
Computer simullation for each technique of the tube drawing:
Manufacturing methods and purposes by the tube drawing are various, and products suitable for purposes are made by changing the combination of the die and plug. In this study, Eiasto-Plastic FEN analysis with the finite element method was applied to each technique of the tube drawing, and the thermal distribution under the process, rcsidual stress after the process and thermal change, which were difficult to be obtained by an experiment, were obtained.
Study of butted tube with ultrasonic vibration:
Butted tube has a stage difference on the inside and outside surface of the tube. Its drawing processes contain sinking, mandrel drawing, plug drawing and expansion drawing. It is used for a body of a bicycle, motorbike and so on. The optimum die angle by drawing force and plug force in each butted tube drawing with ultrasonic vibration added was studied in this report. Ultrasonic vibration was added to plug and die to the axial and radius direction respectively. And the distributions of the axial directional surface residual stresses of each butted tube were studied by the experiment.
Influence of die shape on wire drawing bv Elasto-plastic FEM Analysis:
In wire drawing, the die approach shape causes a crack and fracture in the center of the wire, simultaneously decides optimum drawing condition, and effects the material property of wire after drawing. In this study, based on die-wire contact length ratio l/d0, the influence of the drawing stress and surface residual stress on the wire are examined.
Key Words : Residual stress, Drawing, Die, Wire
Three-dimensional Elasto-plastic Finite Element Method Analysis on the Influence of the Drawing Direction Angle in Die-wire Drawing:
The optimum drawing direction angle in manufacturing of the fine line coil was simulated by the three-dimensional elasto-plastic FEM analysis. The diameter of the fine wire coil after being rolled up is dependent on the drawing direction angle at the entrance or exit of the drawing die. The entrance angle when the fine wire entered the die and the exit angle when the fine wire left the die were exarnined. The drawing in setting angle at the die exit was effective in the diameter of the coil after being rolled up. Various parameters such as drawing direction angle and residual stress that influenced the drawing in setting angle were examined, and the useful data was obtained.
Key Words : Finite Element Method, Drawing, 3-D Analysis
X-ray Analysis of Residual Stress and Texture in Titanium Wire Drawing:
Residual Stress Distribution of TiC Film by CVD:
The materials have been used under the very severe conditions and the devehpment of the technology which coats the surface of the existing cheap structural material in a super material thin film has been required. In this study, by using the CVD method, the residual stresses in the covering film formation were analyzed writh FEM, and the distributions of the residual stresses changed by the various conditions were examined.
Key Words: Coating, CVD, TiC, Residual Stress
Computational Mechanics / Molecular Dynamics
Kansai Univ.｜Graduate | Engineering｜Mechanical Engineering｜ MEMM Lab.