Abstract of Special Research Report (RR-97)
National Institute of Occupational Safety and Health, Japan
Application of Thermoelastic Effect to Determination of Stress Concentration Factors and Stress Intensity Factors
RR-97-1 |
Yoshio KITSUNAI, Takashi HONDA and Tetsuya SASAKI |
: The local stresses and strains near notches and cracks are very important for fracture analysis of cyclically loaded structural components. A number of experimental techniques such as photo elasticity and numerical methods such as finite element analysis have been developed to evaluate stresses or strains near notches. A thermoelastic method is a relatively new stress analysis technique based on the measurement of infrared radiation emitted from the surface of a body as a result of change in temperature arising from a change of stress. In this study, to confirm the validity of the thermoelastic method, stress concentration for several notches in sheet specimens and stress intensity factors of CT and CCT specimens were analyzed by the thermoelastic stress analysis technique. The results were compared with theoretical and analytical results. |
Evaluation of Human Pain Tolerance for Human-Oriented Robot Design
RR-97-2 |
Hiroyasu IKEDA and Noboru SUGIMOTO |
: Domestic and international standards or regulations for industrial robots strictly recommend that these robots should be isolated from operators and other workers. However, there will be many fields in the future where humans will have to allow robots to work besides them. One typical application will be a robot usage in labor assistance and rehabilitation for the aged people or with disabilities. Other applications may include a non-autonomous robotic system designed for cooperative tasks with a human operator. |
Statistical Analysis on Human Factors concerning Falling-accident in Construction Works
RR-97-3 |
Yoshimi SUZUKI, Shin-nosuke USUI, Yoshiyuki EGAWA and Takuro SHOJI |
: Although industrial injuries in Japan have decreased as a whole, the number of cases in construction industry accounts for about 40% of the total casualties(deaths) and trend in the cases by falling-accident is increasing recently. |
Stability of Composite Ground Improved by Deep Mixing Method during Construction of Embankments
RR-97-4 |
Noriyuki HORII, Yasuo TOYOSAWA, Satoshi TAMATE, Hideo HASHIZUME and Yasuhiko OKOCHI |
: Deep Mixing Method(DMM) is often utilized to control the large deformation or failure during construction of embankments and other soil structures. However, the evaluation method for the strength of improved composite ground has not been established in a practical aspect. In this study, centrifuge model tests were carried out to investigate the effect of improvement by the deep mixing method. Four kind of model tests were carried out. These were (1) non improved ground, (2) deep improved ground under the toe of the embankment, (3) deep improved ground under the shoulder of the embankment, and (4) shallow improved ground under the shoulder of the embankment. In addition to centrifuge model tests, numerical analyses by means of Finite Element Method and Circular Sliding Method were performed to appreciate the experimental results. |
Deformation and Failure Behavior of Anchored Retaining Wall Induced by Excessive Exacavation in Centrifuge Model Tests
RR-97-5 |
Yasuo TOYOSAWA, Noriyuki HORII and Satoshi TAMATE |
: Accidents due to collapse of anchored retaining wall occasionally occur in excavation site. To study the deformation and failure behavior of anchored retaining wall, centrifuge model tests were carried out by using an in-flight excavator. Three different models which consisted of different layer such as (1) Kanto loam, (2) sand and (3) a stratum of Kanto loam layer and sand layer with anchors were tested to observe the anchored sheet pile wall's collapse. Based on the results of these centrifuge model tests, the development of the earth pressures and the strains on a sheet pile wall during excavation process and failure mechanisms are discussed. |
Dust Explosibility of Magnesium and Its Alloys
RR-97-6 |
Toei MATSUDA |
: A large number of violent dust explosions have been caused by light metals, such as aluminum and magnesium, which show the most severe dust explosion hazard because of their high heats of combustion, particularly in finely divided states. This fact would lead to the requirement that all aspects of explosion hazards of these dusts should be disclosed and understood for their safer industrial use and manufacture. The ignition and combustion of light metals have been fairly well studied by many researchers and useful information on metal dust explosibilities has been provided by the U.S. Bureau of Mines and German organizations. However, their dust explosibility data in recent testing apparatuses have been limited, and the available data on the explosibility characteristics of metal alloys are contradictory in part. |
Study on Chemical Reaction Hazards of Organic Solvents (2nd Report) --Reaction Mechanism of Epichlorohydrin-Dimethylsulfoxide Mixture--
RR-97-7 |
Takayuki ANDO |
: Although the potential hazards of the solvents are usually discussed on fire or explosion hazard, some solvents show thermal hazards such as exothermic decomposition and/or exothermic reaction with the solute, which are found, for example, in distillation processes. |
Estimation of Activation Energy for Decomposition of Unstable Substances
RR-97-8 |
Teruhito OHTSUKA |
: When a chemical storaged, it's very important to know how fast they decompose and how much heat flow comes from them. But in some cases, the temperature to start decomposition and its melting point are very close, the decomposition temperature measurement will be impossible. In this paper, the method to measure some properties about chemicals like above by measuring with pressure, is proposed. Lauroyl peroxide (LPO) was chosen as an example. |
Insulation Degradation of Printed Circuit Board Caused by Electrochemical Migration
RR-97-9 |
Tatsuo MOTOYAMA and Kenji ICHIKAWA |
: Recently, high density wiring boards have been used in electronic devices in order to achieve its small sizing, therefore the intensity of electric field between lines has become high. On the other hands, electronic devices such as a control apparatus, measuring systems and so on have been used in atmosphere of not only indoor but also outdoor especially in chemical plants where corrosive gases exist. Humidity and corrosive gases accelerate insulation degradation caused by electrochemical migration and failure of electronic devices occurs. |
Self-Consistent Simulation of Charged Powders
and its Application to Evaluating Electrostatic Hazards
RR-97-10 |
Atsushi OHSAWA |
: During the handling and processing of powders, it is well known that charge accumulate on the powder particles. When these charged powders enter and accumulate in a vessel, a large amount of charge can be stored and can lead to electrostatic hazards. To prevent such hazards, it is important to understand the mechanism of the formation of the hazards. In this paper, we present a self-consistent simulation of charged powder entering a vessel for modeling electrostatic phenomena and evaluating electrostatic hazards. |