Mechanical Properties of Woodceramics According to Carbonizing Temperature -Bending, Compression and Hardness-

Hee Seop Byeon,Sang Yeol Ahn,Seung Won Oh,Jin Ji Piao 한국목재공학회 2004 목재공학 Vol.32 No.3

Mechanical effects of polishing pad in copper electrochemical mechanical deposition for planarization?

Sukhoon Jeong,Sangjik Lee,Boumyoung Park,Hyoungjae Kim,Sungryul Kim,정해도 한국물리학회 2010 Current Applied Physics Vol.10 No.1

ECMD (electrochemical mechanical deposition) process consists of a traditional ECP (electrochemical plating) mechanism and a mechanical component. That is, this technique involves both electrochemical plating and mechanical sweeping of the material surface by the polishing pad. The mechanism of the ECMD process may be achieved through two mechanisms. The first mechanism may be the electrochemical plating on the surface where mechanical sweeping of polishing pad does not reach, and the second mechanism may be that the plating rate in the area that is mechanically swept may be reduced by the polishing pad. In this study, the effects of the mechanical component were investigated through various polishing pad types and hole ratios. In comparison to various polishing pad types using the manufactured the ECMD system, the plating rate and WIWNU (within wafer non-uniformity) using the experimental non-pore polishing pad were better than those of the experiments using other polishing pads.

Studies on the Correlation between Mechanical Properties and Ultrasonic Parameters of Aging 1Cr-1Mo-0.25V Steel

Seok Chang-Sung,Kim Jeong-Pyo The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.2

Mechanical properties of in-service facilities are required to evaluate the integrity of power plants and chemical plants. Non-destructive technique can be used to evaluate the mechanical properties. To investigate the mechanical properties using ultrasonic technique, the four classes of thermally aged specimens were prepared using an artificially accelerated aging method. Ultrasonic tests, tensile tests, fracture toughness tests, and hardness tests were performed for the specimens. Then the mechanical properties were compared with ultrasonic parameters such as attenuation and non-linear parameter. From the investigation, we confirm that the ultrasonic parameter can be used to evaluate the mechanical properties.

Mechanical properties of ultra-high-performance fiber-reinforced concrete: A review

Yoo, D.Y.,Banthia, N. THE CEMENT ASSOCIATION OF JAPAN 2016 CEMENT AND CONCRETE COMPOSITES Vol.73 No.-

A comprehensive investigation into the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC), considering various influential factors, is imperative in order to obtain fundamental information for its practical utilization. Therefore, this paper reviewed the early-age strength (or setting) development and mechanical properties of hardened UHPFRC. In connection with the latter, the effects of the curing conditions, coarse aggregate, mineral admixtures, fiber properties, specimen size, and strain-rate on the mechanical performance of UHPFRC were specifically investigated. It was obvious that (1) heat treatment accelerates the hydration process, leading to higher strength; (2) a portion of the silica fume can be replaced by fly ash, slag, and rice husk ash in mechanical perspective; (3) the use of deformed (hooked and twisted) or long straight steel fibers improves the mechanical properties at a static rate; and (4) high rate loading provides a noticeable increase in the mechanical properties. Alternatively, there are some disagreements between the results from various 'size effect' tests and the effectiveness of using twisted steel fibers at static and high rate loadings. Further research to reduce the production cost of UHPFRC is also addressed in an attempt to make its widespread use more practical.

Mechanical effects of polishing pad in copper electrochemical mechanical deposition for planarization

Jeong, S.,Lee, S.,Park, B.,Kim, H.,Kim, S.,Jeong, H. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.1

ECMD (electrochemical mechanical deposition) process consists of a traditional ECP (electrochemical plating) mechanism and a mechanical component. That is, this technique involves both electrochemical plating and mechanical sweeping of the material surface by the polishing pad. The mechanism of the ECMD process may be achieved through two mechanisms. The first mechanism may be the electrochemical plating on the surface where mechanical sweeping of polishing pad does not reach, and the second mechanism may be that the plating rate in the area that is mechanically swept may be reduced by the polishing pad. In this study, the effects of the mechanical component were investigated through various polishing pad types and hole ratios. In comparison to various polishing pad types using the manufactured the ECMD system, the plating rate and WIWNU (within wafer non-uniformity) using the experimental non-pore polishing pad were better than those of the experiments using other polishing pads.

The Mechanical Properties of Lean Clay Filler under Freeze-thaw and Thermostatic Curing Cycles in Loess Plateau

Xiaoqiang Liu,Jiankun Liu,Yahu Tian,Yupeng Shen,Dan Chang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.4

The subgrade filler weakens its mechanical property after suffering from freeze-thaw (F-T) cycles, which threatens the trains' operation safety. It is essential to study the filler's mechanical property's evolution with the F-T cycles and reveal the test factors' incidence on the mechanical parameters. This study conducted a series of unconsolidated and undrained (UU) triaxial shear tests in the F-T and thermostatic-curing (T-C) groups, considering the temperature, confining pressure, and cycle times. As the control group, the T-C group can more prominently reflect the F-T effects on the soil's mechanical parameters, including the stress-strain curve, shear strength, and strength index. A piecewise and linear function can fit internal friction angle or cohesion's change with cycle times, respectively. The fitting parameters reflect the T-C and F-T effects on soil's mechanical properties. The absolute degree of incidence reveals the correlation between mechanical parameters and test factors. The -15°C has the most significant incidence than -5°C and 20°C in shear strength, while -5°C has the most considerable incidence than -15°C and 20°C in friction angle or cohesion. The water distribution and volume expansion due to the F-T cycles are the main reasons determining mechanical properties' evolution with the cycle times in different negative temperatures.

Investigation of Interfacial and Mechanical Properties of Various Thermally-Recycled Carbon Fibers/Recycled PET Composites

백영민,신평수,김종현,박하승,권동준,K. Lawrence DeVries,박종만 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8

The mechanical and interfacial properties were evaluated for carbon fiber reinforced composites (CFRC) manufactured using thermally recycled waste carbon fiber and recycled polyethylene terephthalate (PET). The mechanical properties of the recycled fiber were determined and compared to those of neat fibers using the single-fiber tensile test. The surfaces of the recycled and neat carbon fiber were examined and compared using FE-SEM and dynamic contact angle measurements. A goal of the study was to determine the applicability of industrial use of recycled CF and/or recycled PET in CFRC. Mechanical properties were measured using short beam and tensile tests. These properties were observed to be correlated with crystallinity. The interfacial properties between the recycled carbon fibers and recycled PET were evaluated using the microdroplet test. At low temperature residual resin remained on the recycled CFs surface resulting relatively the low interfacial properties. At excessively high temperatures, oxidation occurred, on the CFs surface, which also resulting in relatively poor low mechanical properties. The optimal treatment condition was 500 oC, where the surface was relatively clean and the reduction in mechanical properties was minimized.

산불 피해목의 재질변화에 관한 연구 (2) -산불 피해 소나무의 경시적 재질변화-

박정환 ( Jung Hwan Park ),박병수 ( Byung Soo Park ),김광모 ( Kwang Mo Kim ),이도식 ( Do Sik Lee ) 한국목재공학회 2008 목재공학 Vol.36 No.1

Degradation of mechanical properties of fire-killed Korean red pine has been investigated after death in 5 years period. Impact bending absorbed energy was the most sensitive property by elapsed time after forest fire. It is an indication of incipient decay of the wood and can be useful indicator to monitor any change of mechanical property of fire-killed tree after death. Degradation of mechanical properties was more pronounced in sapwood than heartwood. Impact bending absorbed energy was more reduced than any other properties in both sapwood and heartwood, while compressive strength was least impacted by elapsed time after forest fire. It is recommended that the fire-killed Korean red pine can be harvested in one year after the fire for industrial uses by considering decay and consequent changes of mechanical properties.

Effects of manufacturing process and surface treatments on mechanical properties of PLA/SCF composites using extrusion printing

Zhiyong Ma,Zheng Qian,Jiabin Cai 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

Short carbon fiber (SCF) reinforced polylactic acid (PLA) composites were fabricated by extrusion printing, and the effects of process parameters and surface treatments on the mechanical properties of composites were studied. Based on the rheological properties of composites and the extrusion process simulation, pure PLA specimens and PLA/SCF specimens were manufactured under different printing parameters. Three kinds of surface treatment were adopted to improve the mechanical properties. The experimental results show that SCF can effectively improve the tensile strength and bending strength, but the compressive strength decreased. The specimen had the best mechanical properties when the layer height was 0.1 mm and the nozzle diameter was 0.6 mm. The mechanical properties can be further improved by coupling agent coating method, and the compressive strength was even higher than that of pure PLA specimen. The research in this paper can provide a reference for the fabrication of thermoplastic composites with excellent mechanical properties by extrusion printing.

Predictive carbon nanotube models using the eigenvector dimension reduction (EDR) method

Zhimin Xi,윤병동 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.4

It has been reported that a carbon nanotube (CNT) is one of the strongest materials with its high failure stress and strain. Moreover, the nanotube has many favorable features, such as high toughness, great flexibility, low density, and so on. This discovery has opened new opportunities in various engineering applications, for example, a nanocomposite material design. However, recent studies have found a substantial discrepancy between computational and experimental material property predictions, in part due to defects in the fabricated nanotubes. It is found that the nanotubes are highly defective in many different formations (e.g., vacancy, dislocation, chemical, and topological defects). Recent parametric studies with vacancy defects have found that the vacancy defects substantially affect mechanical properties of the nanotubes. Given random existence of the nanotube defects, the material properties of the nanotubes can be better understood through statistical modeling of the defects. This paper presents predictive CNT models, which enable to estimate mechanical properties of the CNTs and the nanocomposites under various sources of uncertainties. As the first step, the density and location of vacancy defects will be randomly modeled to predict mechanical properties. It has been reported that the eigenvector dimension reduction (EDR) method performs probability analysis efficiently and accurately. In this paper, molecular dynamics (MD) simulation with a modified Morse potential model is integrated with the EDR method to predict the mechanical properties of the CNTs. To demonstrate the feasibility of the predicted model, probabilistic behavior of mechanical properties (e.g., failure stress, failure strain, and toughness) is compared with the precedent experiment results.