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Table 4.6: Comparison of load transfer between simulation and experiment Location / Type of Strain 0 Layers 8 Layers 164 Percentage of Reduction (%) S2-Hoop Strain (Experiment) 401.14 380.12 5.24 S3-Hoop Strain (Experiment) 440.82 378.04 14.24 S5-Hoop Strain (Experiment) 479.77 356.86 25.62 *Defect Hoop Strain (Simulation) 402 365.87 8.99 S2-Axial Strain (Experiment) 363.41 287.65 20.85 S3-Axial Strain (Experiment) 285.77 218.62 23.50 S5-Axial Strain (Experiment) 301.86 284.8 5.65 *Defect Axial Strain (Simulation) 114.4 95.36 16.64 S4 - Hoop Strain (Experiment) 278.28 255.16 8.31 *Nominal Hoop Strain (Simulation) 265.81 267.34 -0.58 S4 - Axial Strain (Experiment) 68.38 66.13 3.29 *Nominal Axial Strain (Simulation) 2.2 5.99 -172.27 Nevertheless, these achieved results which are based on the test rig arrangement, have already met the objectives of this PhD study. In earlier discussions, the test rig that mimics the actual pipeline on site focuses on a straight pipe which relates to offshore or onshore pipelines rather than other shapes and it refers to above the ground pipelines only. In other research carried out by Lukacs et al. (2010), they conclude that in any experimental work (i.e. laboratory-based) which involves straight pipes, researchers are more concerned with hoop strain rather than axial strain. This is because of the nature of the test set-up itself which requires the pipe to have a closed system at both ends. Unlike the underground or buried pipelines which are subjected to soil movement, the axial strain is more important than hoop strain and the test set-up should be arranged in a different form.
Mircostrain 600 500 400 300 200 100 0 Figure 4.26: Strain distribution of experiment and simulation Figure 4.26 also shows that the experimental hoop and axial strains measured at different locations along the circumferentially arc-shaped notch show slightly different results. This is because the strain gauge elements were installed at different orientations. The orientation of the strain gauge or sensor at the S3 location has produced better strain readings and this technique will be adopted in future strain gauge installations on any biaxially loaded pipe. This is agreed by Freire et al. (August 2006) who also highlight the importance of the experimental technique using sensors. According to them, the laboratory test is crucial because it gathers benchmark experimental results that will be used to verify analytical or numerical stress calculation procedures. 165 0 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
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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
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 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 183: Mircostrain 300 250 200 150 100 50
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
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
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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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