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Table 4.3: The experimental strain results at defect and nominal areas in the composite repair Location / Type of Strain 0 layer 2 Layers 4 Layers 6 Layers 8 Layers 154 Percentage of Reduction (%) S3-Hoop Strain 440.82 429.87 406.28 398.42 378.04 14.25 S3-Axial Strain 285.77 268.26 239.43 224.47 218.62 23.5 S4-Hoop Strain 278.28 276.08 274.43 266.76 255.16 8.3 S4-Axial Strain 68.38 72.3 67.82 70.8 66.13 3.29 Table 4.3 and Figure 4.20 show some significant amounts of load transfer at the defect and nominal areas after the completion of 8 layers of composite. The percentage of reduction that represents the amount of load transfer is defined as the difference between the strain before (without repair) and after repair (with 8 layers of composite material) divided by the strain before the repair multiplied by 100. At S3, about 14.25% load is transferred in the hoop (i.e. percentage of reduction) and 23.5% in axial directions; only 8.3% and 3.29% of hoop and axial load transfers occur at S4. This shows that the composite takes more load at the defect area than at the nominal area.
Mircostrain 500 450 400 350 300 250 200 150 100 50 0 S3-Hoop Strain S3-Axial Strain S4-Hoop Strain S4-Axial Strain Figure 4.12: The load transfer behaviour from reinforced material (steel) into the reinforcing material (composite) as the thickness of composite increases In this experiment, the technique of installing the strain gauge is of paramount importance. There are three significant locations of strain gauges, as shown in Figure 4.21. This shows that the orientation of each element of the rectangular strain gauge rosette plays a significant role in determining the more accurate and steady measurement. S3 in Figure 4.22 shows the most steady reduction of strain readings compared to S2 and S5, although all of them were installed along the circumferentially arc-shaped defect, as shown in Figure 4.21. 155 0 layer 2 Layers 4 Layers 6 Layers 8 Layers
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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
Page 123 and 124: Table 3.8: The effect of repair len
Page 125 and 126: four up to 18 layers. In this study
Page 127 and 128: hoop and axial stress concentration
Page 129 and 130: Table 3.11: Predicted Elastic Const
Page 131 and 132: Table 3.13: Axial Stress v/s L/W ra
Page 133 and 134: Hoop Stress (MPa) Figure 3.3: Hoop
Page 135 and 136: However, Frost (2008) and Alexander
Page 137 and 138: Table 3.17: Ratio of Axial Stress N
Page 139 and 140: axial load (e.g. buried pipelines t
Page 141 and 142: 3.10 Numerical Strain Analysis of C
Page 143 and 144: Figure 3.36 shows the contours befo
Page 145 and 146: Stress Concentration Factor 2 1.8 1
Page 147 and 148: In fact, for Notch 40 with 18 plies
Page 149 and 150: this second approach (i.e. the expe
Page 151 and 152: 4.2.2 Strain Gauge Selection and Cr
Page 153 and 154: Finally, a method used to calculate
Page 155 and 156: Where, and are the maximum and mini
Page 157 and 158: 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: However, the axial load transfer is
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 183 and 184: Mircostrain 300 250 200 150 100 50
Page 185 and 186: Mircostrain 600 500 400 300 200 100
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 and 210: The above results show that shear s
Page 211 and 212: shear strains becomes more stable a
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
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Proceedings of OMAE'01 20th Interna
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Greenwood, R. (2002), UKOPA Pipelin
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Kotrechko, S. A., Krasovskii, A. Y.
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Mousavi, S. E., Xiao, H. and Sukuma
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Raju, I. S. and Newman, J. C. (1986
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Tennyson, R. C. and Mufti, A. A. (2
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Xue, L., Widera, G. E. O. and Sang,
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General Technical Specifications: T
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Photos of the Design and Build of t
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Composite Installation Process usin
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APPENDIX 3 - STRAIN GAUGE INSTALLAT
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Figure 7: Mylar tape was stuck onto
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Figure 19: Repeating the above proc
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2) Electrical Insulation Test Resul
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