United States Department of Transportation
i
Puncture Resistance of Scale Model Aluminum Tank Car Heads
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1987-06-01
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[PDF-7.28 MB]
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Abstract:In the study of the coupler-tank car head impact phenomena in derailment and switchyard operations, different test conditions have to be considered. In order to correlate the threshold puncture velocity with these conditions, many impact tests need to be performed to obtain the required information. For these studies, a small-scale model testing program is certainly more desirable over the full scale testing as far as the cost is concerned. It is imperative, however, that the small-scale model impact tests will provide reliable information as to the real full-scale impact phenomena. Therefore, several attempts were made in this study with small-scale impact testing to investigate different tank car head protection devices with different impact conditions. An attempt was made with center impact testing on model aluminum tank car heads: (1) to assess the effectiveness of mitigating materials on increasing the puncture resistance of model aluminum tank car heads; (2) to evaluate the effect of low temperature on the threshold puncture energy of model aluminum tank car heads; (3) to test the validity of the scaling laws adopted on model aluminum tank car heads; and (4) to study the influence of loading on the threshold puncture velocity of model aluminum tank car head in horizontal impact situations. Two additional attempts were made with off-center impact testing on model aluminum and high-alloy steel tank car heads to assess the vulnerability of model tank car heads under off-center impacts. A number of 1/10- and l/5-scale model aluminum and high-alloy steel tank heads were used in this study. Also a Finite Element Model was developed for the prediction of the puncture resistance of scale-model aluminum and high-alloy steel tank car heads. The small-scale impact testing program includes vertical impact tests (drop-weight) and horizontal impact tests (pendulum). These tests were performed on the scale-model tank car bareheads and heads that were covered by high-alloy steel head shields or steel face plates combined with different kinds of mitigating materials. These materials were used as protective devices to increase the puncture resistance of the scale-model aluminum and high-alloy steel tank car heads in the center and off-center impact tests. Several kinds of mitigating materials were selected and examined in preliminary dynamic impact tests to determine the most suitable material-combination with the most energy absorbing capacity which can be used in impact situations. Beside the high-alloy steel head shield (thick steel plate), two different kinds of mitigating materials combined with steel face plates (thin steel plates) were chosen and used in the center impact tests, while only one of the two mitigating materials combined with steel face-plates was used in the off-center impact tests. This mitigating material was formed from several layers of aluminum honeycomb combined with thin sheets of high-alloy steel; the second material was formed from a single plate of Hytrel Polyester Elastomer "Tecspak" combined with a single thin sheet of high-alloy steel. The test results indicate that all the protective devices provide good protection to the scale model tank car heads against impact puncture as compared with the barehead impact situation. However, some differences in terms of protection capability between these protective devices in each scale were found.
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