Thesis (M.S)--Ohio University, November, 2004. / Includes bibliographical references (p. 93-95)

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains x, 71 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 64-68).

Thesis (M. Sc.)--University of Hong Kong, 2002. / Also available in print.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Raymond Shreeve, Garth Hobson. Includes bibliographical references (p. 91-93). Also available online.

Thesis (M.S)--Ohio University, November, 2004. / Title from PDF t.p. Includes bibliographical references (p. 93-95)

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Excessive vibration exerted on the human body can cause many harmful phenomena that can result in permanent bodily damage or permanent disability. Human vibration is classified into two main categories: Hand,arm vibration and whole,body vibration. Hand,arm vibration is vibration transmitted through a percussive tool handle via the hand,arm system to the rest of the body. The main diseases concerning hand,arm vibration are Vibration White Finger (VWF), neurological diseases in the hand and fingers and musculoskeletal diseases like carpal tunnel syndrome. These diseases, especially VWF and musculoskeletal disorders, are mainly associated with lower frequencies. VWF in particular is more likely to occur when an operator is subjected to vibrations with high magnitudes in the 25-40 Hz region. The operating frequencies of most rock drills vary between 30 and 50 Hz. Although there are many other contributing factors like grip force, hand temperature and subject variability, prevalence of VWF among rock drill operators is relatively high in the world. The situation in South Africa is not yet very clear, and further research must be done to evaluate the current status of VWF in South Africa. Vibration energy at higher frequencies can be attenuated with rubber grips or gloves, and these types of dampers are already available on the market. The problem concerning the operating frequency of the drill has not yet been successfully addressed, and thus remains a problem in the rock drill industry as it is at the moment. The main objective of this thesis was the development and testing of a concept that can potentially be implemented on a rock drill to attenuate the operating frequency of a rock drill. The concept must be able to account for minor changes in operating frequency on a specific drill. In addition to that, the drill operating frequency varies from one drill to another. The thesis also aims to lay the mathematical foundation to design an attenuating handle for a specific drill with a specific operating frequency. All the objectives must be obtained without noticeable sacrifices in drill control or performance. The thesis includes the concept generation, optimisation, design and manufacture of a rock drill vibration absorber. The absorber has been tested, and the results are presented. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Among semi-destructive methods of measuring residual stresses in elastic materials, the blind hole-drilling strain-gage method is one of the best because it is simple, economical and accurate. It is based on the measurement of strains disturbed by machining a small diameter shallow hole in the test piece. The strains measured in three known directions permit the determination of the direction and magnitude of principal stresses and subsequently of any stress in any direction. This thesis presents the investigation of residual stresses in the longitudinal direction of a welded fabricated steel tube of 22 inch diameter, relating to a series of holes drilled in one half of a circular section of the tube. An initial assumption, substantiated later, was the existence of a uniform field of residual stresses through the thickness of the tube. Several methods for determining calibration coefficients are documented. The values of longitudinal stresses once computed are presented in a smooth curve. A straight line approximation is reconnnended for use in further studies of the effects of residual stresses on failure loads.

The purpose of this thesis might be subdivided under two headings - modification of the testing machine so that it would be suitable for drilling tests and development of a standard drilling test for machinability which would employ the modified machine. The first mission was accomplished by the substitution of a specimen-holder in the form of an angle iron for the tool holder already attached to the carriage. One other modification consisted of replacing the timing circuit of the machine with a 1 rpm indicator card mount which, together with a recording pen, gave a pictorial record of the progress of the drill through test specimens. The second purpose of the investigation was fulfilled when the straight line portion of the machinability curve was found, proved, and defined by equation. Also of equal interest with regards to this machinability concept was the establishment of confidence limits showing the relative variability of the materials tested. Perhaps the statement should be made that the exact values of these confidence limits depend on the number of test specimens being included in the index determination. The investigators based their calculations on a sub-group containing four specimens. This sub-group size was believed sufficiently high to detect any test equipment defect, such as a feather edge on the drill or an incorrectly set speed, without requiring an excessive number of drilling operations. Although the index values calculated and listed in Table #13 are correct for the materials tested, they are not recommended for general use since they are based on test specimens all coming from one source. A larger number of tests on specimens from a large number of foundries and steel mills would be necessary for a true estimate of the machinability of the test materials. / M.S.