Papers by Keyword: Ultrasonic Technique

Abstract: For structural health of mechanical structures, non-destructive detection and material defect characterization represent the main useful tools for mechanical decay prediction caused by local composite damage phenomena. In this work, internal delamination due to alternate bending were characterized in flat specimens, performing fatigue and static tests, coupled with thermographic, optical, and ultrasonic analysis for damage detection and evolution purposes. Damage to rupture behavior of CFRP material through mechanical tensile tests is performed on several samples and non-destructive inspection procedures are optimized during successive HCF tests to detect in real time local compliance variations and damage initiation. Thermographic continuous monitoring and occasional ultrasonic analysis are implemented to analyze composite anomalies during fatigue life and to elaborate a procedure for identification of delamination induced damage before failure. IRT and UT results are computed with MATLAB analysis for damage evaluation with strain and compliance data acquired during tests.

Abstract: Here a novel technique was employed to fabricated three-dimensionally porous polystyrene (PS) films via ultrasound assisted template method. In contrast to spin-coated thin film, different morphologies appeared on the films prepared by casting PS/toluene solution on glass substrates. By varying either systematic parameters or intrinsic parameters, surface structures changed from two-dimension flat pores to three-dimension sponge pores. The influences of ultrasonic intensity, frequency, irradiation time, film thickness and toluene content in water bath on surface morphologies were extensively studied. Scanning electron microscopy and white-light confocal microscopy showed that PS casted films with thickness of 200μm have a higher porosity and lower surface roughness within micrometer range. The contact angle measurement indicated slight changes of surface hydrophilicity with toluene content in water bath. Suitable toluene content favored multilayer formation of PS film and led to monodisperse pore distribution analyzed by ImageJ.

Abstract: -Fe-Cr phase was investigated using formula Fe₈₀Cr₂₀. Ball milling process and ultrasonic technique is successfully done to develop solid solubility and improve homogenous, respectively. However, the effect of the Cr to Fe powder is not complete investigated using combination of its process. Ball milling is conducted by milling time of 60 hours and ultrasonic technique were carried out at ultrasonic time of 3 h, 3.5 h, 4 h, 4.5 h and 5 h. From the strain effect analysis is obtained that the strain increased with crystallite size decreased and broad peaks due to the micro strain that is obtained from the increasing d-spacing. The solid solubility and lattice parameter of the material relatively increased from the untreated sample to treated samples with the highest solid solubility of 62.1% and highest lattice parameter of 3.091 nm which is located at the milled and UB 4.5 hours. It is caused the temperature increased that effect to the higher diffusion of the atom. Therefore, the combination treatment is highest promote to improve the properties of the metallic materials.

Abstract: Zinc phosphate molecular sieve were synthesized using zinc chloride, phosphoric acid as a zinc and phosphor source, respectively. Different types of zinc phosphates zeolites were synthesized by conventional hydrothermal (using (2-hydroxyethyl) trimethylammonium hydroxide (2-HETMAOH) as new template. Also, ethylene glycol (EG) was utilized as co-solvent and ultrasonic tool was applied as mixer. The influence of the chemical composition of the starting sol-gel and the other parameters such as, Zn/P mole ratio, time of microwave irradiation were studied.

Abstract: Hydrogen embrittlement is a common problem for the integrity of oil conducting pipes. In this work, we estimate the rate of hydrogen penetration into an API 5L steel pipe welded by electric arc. The hydrogen penetration was estimated by means of data taken from ultrasonic measurements. As expected, the steel pipe becomes more brittle as the hydrogen penetration rate does so. A simple diffusion model was developed. The model confirms the strong dependency between the rate of penetration and the mechanical damage to the material.

Abstract: It's required that mechanical properties of in-service facilities maintain the safety of operation in power plants as well as chemical plants. In this study the four classes of thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method at 630°C. Ultrasonic tests, tensile tests, KIC tests and hardness tests were performed in order to evaluate the degree of the material degradation. The mechanical properties deteriorated as the specimen degraded, but the attenuation coefficient and the harmonic generation level of the ultrasonic signal increased. The non-linear parameter derived from the harmonic generation level is especially sensitive and will be a good parameter to evaluate the material degradation.