英文report模版

Imperial College London

Department of Mechanical Engineering

Investigation into the Safety Factors of a

Fairground Ride

Tianxin Weng

Group 9C

26th Nov 2010

Abstract

The goal of this experiment is to assess the safety of a modification on a fairground ride. The modification is a hole drilled on the connection arm for light decoration. The experiment was carried out in three steps: tensile test to determine the yield stress, UTS and Young‟s modulus; determination of strain gauge factor and determination of the stress concentration factor and safety factors for the modification. First, a tensile test for the same material used in the fairground ride (steel) was carried out. The yield force and ultimate tensile force were read from the graph produced by the apparatus. For the strain of the plate to be measured more precisely, a calibration of electronic gauge (that would be used in stage three) is carried out by a four-point-bend experiment. The gauge factor would be the outcome of this stage. In third stage, load would be applied on a plate with gauges on the surface within its elastic region. Stain values was read by the gauge mounted on the plate. The ratio of maximum strain and the nominal strain is the stress concentration factor in this case. The stress concentration factors would be worked out by using the ratio of failure stress and the working stress.

The safety factors (S.F.) with a hole are 2.27±0.23 for yield and 2.75±0.28 for fatigue. They were 8.0±0.16 for yield and 9.7±0.20 for fatigue without a hole. The quantity of S.F. drop is significant due to the hole. The results show that it isn‟t safe for the fairground to make the modification.

The alternative suggestion for the fairground is using the sticky flash light instead of drilling a hole. It has the same appearance for attracting the tourist but maintain the safety factors.

Nomenclature

x Extension of the specimen

L The original length of the specimen G Gauge factor

Fractional uncertainty of …X‟

E Y oung‟s modulus

Surface strain

σ Tensile stress

Diameter

Contents

Abstract (i)

Nomenclature ....................................................................................................................................... i i

1. Introduction (1)

2. Methods (2)

2.1 Tensile test of steel (2)

2.2 Calibration of the gauge (3)

2.3 Stress Concentration Factor test (4)

3. Results (6)

3.1 Recording and processing data of the tensile test (6)

3.2 Recording and processing data of the calibration (8)

3.3 Recording and processing data of the S.C.F. (9)

3.4 Evaluation of the new safety factors (9)

4. Discussion (11)

5. Conclusion (12)

6. Reference (13)

Appendix 1 Tensile test graph (14)

Appendix 2 Calculation of the working stress (15)

Appendix 3 Calculation of the cross-section area (16)

Appendix 4 Calculation of the Young‟s modulus (17)

Appendix 5Yield and ultimate tensile stress (18)

Appendix 6 Calculation of thickness of the bar and the distance between two inner stands (19)

Appendix 7 Calculation of the gauge factor (21)

Appendix 8 the calculation of t he cross-section area of the aluminium plate (22)

Appendix 9 Recording and processing data of the S.C.F. (23)