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first is to calculate the shear angle using the theoretical equation based on the kinematic analysis of the bias-extension test. The second is to draw straight lines along the yarns for various images from the bias test. The third method is to use a series of images obtained from the test along with soft image correlation software. However, all these approaches carried out by the above researchers cannot be used for the woven composite that is wrapped round the pipe. The only way to measure the shear angle, strain and others due to thermal expansion is to apply Mohr‘s Circle theory using a strain gauge and surface temperature detector. 5.6 Summary and Conclusions From the above results, from this experimental approach of using the surface temperature detector, it is possible to measure the CTE of the test material on site provided the measurement is carried out at proper locations; it also provides an alternative method to the bonded temperature sensor which may involve extra cost and time. For unreachable locations, for example, between layers of the composite repair, the temperature sensor has to be bonded next to the bonded strain gauge so that more accurate readings can be obtained. From these experimental results also, it can be concluded that the CTE measurement using this simple approach produced is acceptable and practical in this composite based pipeline repair. However, this approach produces better and accurate result in the isotropic material (i.e. steel) than in the anisotropic material (i.e. composite). The results of maximum thermal strain at both layers (fourth and eight layers) show that the thermal strain is directly proportional to the temperature increase. In the investigation of shear strain in the thermal expansion experiment, the shear strain is found to be higher at the eighth layer (i.e. 172 microstrain) compared to the fourth layer of composite (i.e. 73.3 microstrain). However, at the eighth layer, the shear strain was nearly constant as temperatures increased. Therefore, the CTE readings at C3 and C4 (both at the eighth layer) as illustrated in Figure 5.12, were much closer to each other if compared to C1 and C2 (at the fourth layer) which were less apparent. This shows that 190
shear strains becomes more stable at the outer layers than the inner layers of the composite repair. This study concludes that maximum thermal and shear strain are not only influenced by the temperature but also thickness. The values of shear angle at both fourth and eight layers show inconsistency as the temperature increases from 25 °C to 40 °C. Again, this concludes that in the thermal expansion of the composite material, thermal strain and shear strain are the function of thickness and temperature of the material. But shear angle is less predictable and an accurate relationship cannot be easily established in this anisotropic composite. 191
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CRANFIELD UNIVERSITY MAHADI ABD MUR
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ABSTRACT One of the most common pro
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TABLE OF CONTENTS ABSTRACT ........
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3.7.1 Introduction ................
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5.6 Summary and Conclusions .......
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Figure 3.1: Schematic diagram of th
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Figure 5.4: The average temperature
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NOMENCLATURES ACFM Alternating Curr
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1 INTRODUCTION One of the most comm
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1.1 Objectives Knowing this backgro
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The methodology of this integrated
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Chapter 6 contains the summary and
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period of the major part of the exi
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Figure 2.2: Reported interest in de
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Figure 2.4: Dent damage caused by v
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presented current practices, recent
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Energy Workforce Sdn Bhd (2011) cla
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available provides real time detect
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2.3.3 Reliability Analysis of Infor
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Figure 2.9: Pipeline failure probab
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2.3.3.1 NDT Reliability and POD cur
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increase in the yield limit of stee
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the SCC assessment in their integri
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Manufacturers such as Walkers Techn
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Company L.P, 2005); Aquawrap ® pro
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monitoring, inspection, and damage
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2.6.2 Aims of Structural Health Mon
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Figure 2.16: Application fields and
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egistered by the piezoelectric sens
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discretization error. Round-off err
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notches and Neuber‘s is better fo
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maximum local stress at discontinui
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De Carvalho (2005) concludes that t
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accurate simulation of loading espe
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Based on the above facts, the opera
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3 FINITE ELEMENT ANALYSIS (FEA) IN
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Figure 3.2: Schematic diagram of th
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In this modelling work (i.e. compos
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This partition toolset also helps u
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Figure 3.6: Mesh control using Swee
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Figure 3.7: Schematic representatio
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discretization. Therefore, in this
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According to Staten et al. (2010b),
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3.5 The influence of pressure on th
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each pressure value remains constan
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Axial Stress, σa (S22) was referre
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Figure 3.14 shows a graph of analyt
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the notch defect is found to be in
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One of the contributions of this st
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Table 3.4: Convergence tests on var
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Figures 3.16 and 3.17 show that the
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Figure 3.20 shows that as the relat
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3.7.4 Concluding Remarks A biaxial
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yarns change and lateral contact be
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For predicting E2 and Gl2, a number
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Where: Ar = weight of one sheet of
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Where; The Stiffness matrix is trad
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simulations for the hoop strain at
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Figure 3.24: Finding the hoop stres
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Table 3.8: The effect of repair len
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four up to 18 layers. In this study
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hoop and axial stress concentration
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Table 3.11: Predicted Elastic Const
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Table 3.13: Axial Stress v/s L/W ra
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Hoop Stress (MPa) Figure 3.3: Hoop
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However, Frost (2008) and Alexander
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Table 3.17: Ratio of Axial Stress N
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axial load (e.g. buried pipelines t
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3.10 Numerical Strain Analysis of C
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Figure 3.36 shows the contours befo
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Stress Concentration Factor 2 1.8 1
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In fact, for Notch 40 with 18 plies
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this second approach (i.e. the expe
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4.2.2 Strain Gauge Selection and Cr
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Finally, a method used to calculate
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Where, and are the maximum and mini
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should be between 20 and 28 bar and
Page 159 and 160: welded weld neck flange at both end
Page 161 and 162: Figure 4.7: Sensor and heating elem
Page 163 and 164: Figure 4.9: A summary of data acqui
Page 165 and 166: One of the objectives of doing this
Page 167 and 168: Figure 4.14: A schematic diagram of
Page 169 and 170: Table 4.1: Strain gauge readings at
Page 171 and 172: microstrain 3.00E-04 2.50E-04 2.00E
Page 173 and 174: However, the axial load transfer is
Page 175 and 176: Mircostrain 500 450 400 350 300 250
Page 177 and 178: Since the defect is not a flat notc
Page 179 and 180: Again, the epoxy resin plays a sign
Page 181 and 182: Table 4.4: Study at the defect area
Page 187 and 188: 14.25% in hoop strain and 23.5% in
Page 189 and 190: consideration for the selection of
Page 191 and 192: 5.4 Methodology of Thermal Expansio
Page 193 and 194: Figure 5.1: Some preventive measure
Page 195 and 196: 5.4.1 The Fundamentals of the Therm
Page 197 and 198: 5.5 Analysis of Results 5.5.1 The t
Page 199 and 200: Thermal Output (strain ) 0.0002 0.0
Page 201 and 202: (Strain ,ε) Figure 5.12: Coefficie
Page 203 and 204: (Strain ,ε) 0.0002 0.00018 0.00016
Page 205 and 206: Table 5.1: The strain readings afte
Page 207 and 208: maximum shear strain increase as th
Page 209: The above results show that shear s
Page 213 and 214: for future safe design and operatio
Page 215 and 216: has been fully cured. Poor surface
Page 217 and 218: 6.3 Primary PhD Achievements The ea
Page 219 and 220: In Chapter 5, the CTE was determine
Page 221 and 222: ASM International (2002), "Thermal
Page 223 and 224: Bucinell, R. B. (2001), Calculating
Page 225 and 226: Proceedings of OMAE'01 20th Interna
Page 227 and 228: Greenwood, R. (2002), UKOPA Pipelin
Page 229 and 230: Kotrechko, S. A., Krasovskii, A. Y.
Page 231 and 232: Mousavi, S. E., Xiao, H. and Sukuma
Page 233 and 234: Raju, I. S. and Newman, J. C. (1986
Page 235 and 236: Tennyson, R. C. and Mufti, A. A. (2
Page 237 and 238: Xue, L., Widera, G. E. O. and Sang,
Page 239 and 240: General Technical Specifications: T
Page 241 and 242: Photos of the Design and Build of t
Page 243 and 244: Composite Installation Process usin
Page 245 and 246: APPENDIX 3 - STRAIN GAUGE INSTALLAT
Page 247 and 248: Figure 7: Mylar tape was stuck onto
Page 249 and 250: Figure 19: Repeating the above proc
Page 251: 2) Electrical Insulation Test Resul
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