Dynamic asymmetrical lifting capacity modeling /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | This dissertation presents a study of asymmetrical lifting of bags without handles over an obstruction and was intended to simulate the loading of grocery bags into car trunks. Eighteen male subjects were subjected to an externally-paced task of lifting grocery bags (grasping them at the open end) loaded with plastic bags filled with steel shots from 15 cm (6 inches) above the floor and over a wooden sill which served as an obstruction. There were two different sill heights of 70 cm (27.5 in) and 90 cm (35.5 inches), and for each of these heights there were three different sill depths of 28 cm (11.0 in), 43 cm (17.0 in), and 57 cm (22.5 in). The dependent variables were the maximum acceptable weight of lift and body part discomfort responses. Another independent variable was the subject's anthropometric dimensions. Constant variables were temperature (23-26 degrees celsius), humidity (52%-62%), horizontal distance of lift (100 cm), and time of day the subjects performed the lifting. A modified version of a psychophysical methodology was used to determine the maximum acceptable weight that subjects were willing to lift. An analysis of variance performed on the data showed no significant differences in the weights that subjects lifted across the two sill heights. However, there was a significant difference in the weights lifted across sill depths within each sill height. Weights lifted over the 28 cm (11.0 in) sill depth were significantly more than the weights lifted for either the 43 cm (17.0 in) depth or the 57 cm (22.5 in) depth. There was no significant difference between the weights lifted over the 43 cm (17.0 in) and 57 cm (22.5 in) sill depths. A Linear regression analysis was performed on the data and a set of 8 prediction equations were developed--one for each of the six treatment combinations, and two combination models. These equations were designed to predict the maximum acceptable weight of lift for an individual based on his anthropometric dimensions. Correlation coefficients (R^2) for these models ranged from 0.87 to 0.95. Stature, acromial height, trochanteric height, biacromial breadth, metacarpal III height, and grip strength at elbow angle of 90 degrees were the independent variables common to all the models. The body part discomfort ratings showed significant differences in discomfort for thighs and upper back only. While these ratings were not affected by sill heights, the sill depth of 43 cm (17.0 in) was found to be the least stressful of the three depths evaluated. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Industrial Engineering." |
| Physical Description: | xi, 112 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |