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Study On Stress Measurement For Round Bar By Impact Sound

Nor Liana, Salleh (2010) Study On Stress Measurement For Round Bar By Impact Sound. Masters thesis, Takushoku University.

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For a safety of structures , it is important to know how much stress is working in a structure or a member. Stress has been measured in most cases using a s train gauge. In this technique, we have to attach a gauge to a structure and take a lot of trouble in extending the cable from a measuring device to t he strain gauge and in keeping gauges under proper condition, especially for a long-term measurement . Moreover, in t he case where we kept the strain gauge for several months or about a year and measured it after the internal, the measurement voltage of the strain gauge carries out a drift, and it is though that the measurement with a strain gauge becomes difficult. A new method is desired, where we can measure the stress in a structure even if the interval time of measurement is about a year or two and enables us to measure t he stress s imply and at any time with ease. For example, the generating stress of the rope for hanging the road of a bridge is the equal and same stress value at the time of completion and if t here is measuring method which can simply and accurately measure/ confirm an unusual stress that occur during the time of completion, t he safety of maintenance management of a bridge can be raised further. Moreover, in t he middle of construction until it completes, the situation when big load is hanging on the rope, t he rope that support the weight of t he hanging road is also can be considered. Development of the measurement system which can easily grasp the generating stress of a component is expected over all t he time, necessarily for completion where a bridge is built, and contributes great improvement in the safety control. Recently, without using strain gauge to measure generating stress in a structure, they proposed the change of stress t hat produced heat which brings temperature change as a technique of measuring [2] . However, this technique is restricted to the dynamic load changed in time, Static stress measurement cannot be performed on that principle, and measurement accuracy is also low. Moreover, a hammer etc. pounds on an axis, al though the existence of the sound that generated from the fatigue crack is judge as spot-method and adopted conventionally, quantitative examination is not carried out. Although equipment diagnosis [3] based on the genera ted sound of a machine and a structure is performed widely, for the present condition, accurate evaluation of generated stress is still having no result. This research examined t he validity of the technique of measuring the stress generated in the component using the crashing sound made by throwing a small ball to a beam component. There is also no wiring work needed in the case of measurement with a strain gauge. Moreover, it will give advantage to intermittent measurement which the accuracy of the measurement will not fall off. Round bar with both ends fixed is t he subject of stress measurement, and tensile load, compression axial load, torsion load and bending load are t he subject of t he load working on the round bar. About the case where axial load acts, firstly, the relation between axial stress and natural frequency which acts on t he round bar is theoretically searched. Next, by throwing a small ball to the round bar which generated crashing sound, Fourier analysis was acted,and natural frequency of the round bar was measured experimentally. The natural frequency and corresponding s tress obtained experimentally were evaluated by theoretical result, and compared to the value of actual stress gain from s train gauge that stuck on the round bar, t hen t he stress measurement accuracy of the round bar component by a crashing sound was examined. For the tors ion load and bending load, it was investigated experimentally whether natural frequency would change with the sizes of the load acted on the round bar.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Strains and stresses -- Measurement, Stress concentration
Subjects: T Technology > T Technology (General)
T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Library > Tesis > FKM
Depositing User: Siti Syahirah Ab Rahim
Date Deposited: 28 Oct 2014 17:01
Last Modified: 28 May 2015 04:32

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