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transfers in the axial direction. Again, referring to Equation 3.20, the recommended analytical repair axial length is 155 mm. If we compare the numerical repair length against the analytical repair length, a repair saving of 48% can be achieved through this design optimisation. The longest notch (i.e. Notch 100 Carbon/Epoxy) shows the maximum load transfer in hoop and axial directions occurs at different L/P ratios. The hoop stress load transfer of 13.8% occurs at L/P = 10.71 or a repair length of 160 mm and the axial stress load transfer of 25.11% occurs at L/P = 16.06 or at a repair length of 240 mm. Likewise, the maximum load transfer occurs at L/P = 10.71 for N100 Glass Epoxy with 12.01% in the hoop direction and 24.26% of axial stress load transfer occurs at L/P = 16.06 or a repair length at 240 mm. From the ASME PCC-2 guidelines, the analytical axial repair length is 248 mm only. Hence, a repair saving of only 3% can be achieved in the axial direction. 3.9.1.2 Concluding Remarks Analysis of the above results, shows that PRI has the ability to provide a good and helpful tool to the manufacturer in benchmarking the efficiency of their composite repair in the stress distribution study as well as in the design optimisation of composite repairs in the future. From the previous comparison of results between the numerical PRI and the analytical method (i.e. ASME PCC-2), the optimum length of composite repair, especially for the defect length of 40 mm in this study, is 160 mm as compared to the recommended length by ASME (2010) which is 188 mm. About 20% of stress loading has been transferred in the hoop direction and around 35 ~ 38% in the axial direction. Carbon fibres have given better results than glass fibres throughout the simulation tests. This study also shows that the smaller the notch length, the higher the material saving will be. Nevertheless, in this the PhD experimental work, only Glass Epoxy composite was used. The length of the defect and the length of repair were fixed at 40 mm and 280 mm. The number of plies was limited, i.e. up to eight plies only. 120
3.10 Numerical Strain Analysis of Composite Repair In this section, there are two objectives to be discussed. The first is the continuity of the modelling study from the previous section, but this time with more emphasis on hoop and axial strains. The second objective is to study the significance of a composite repair on the strain concentration factor. 3.10.1 Strain study on the chosen models prior to composite repair Table 3.18: The hoop and axial strain results at notch root Diagram Descriptions (Different Type) Short Pipe with defect of 40 mm (Half Pipe Model – Actual Model in this PhD Study) Symmetrical long pipe with defect of 40 mm (Half Pipe Model) Full Pipe Model with 40mm defect Full Pipe Model with 40 mm defect without flanges 121 E11 (µε)- Hoop strain E22 (µε)- Axial strain Analytical FEA Analytical FEA 460 402.35 108 114.4 460 412.69 108 153.87 460 412.17 108 76.77 460 405.93 108 99.086
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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
Page 89 and 90: According to Staten et al. (2010b),
Page 91 and 92: 3.5 The influence of pressure on th
Page 93 and 94: each pressure value remains constan
Page 95 and 96: Axial Stress, σa (S22) was referre
Page 97 and 98: Figure 3.14 shows a graph of analyt
Page 99 and 100: the notch defect is found to be in
Page 101 and 102: One of the contributions of this st
Page 103 and 104: Table 3.4: Convergence tests on var
Page 105 and 106: Figures 3.16 and 3.17 show that the
Page 107 and 108: Figure 3.20 shows that as the relat
Page 109 and 110: 3.7.4 Concluding Remarks A biaxial
Page 111 and 112: yarns change and lateral contact be
Page 113 and 114: For predicting E2 and Gl2, a number
Page 115 and 116: Where: Ar = weight of one sheet of
Page 117 and 118: Where; The Stiffness matrix is trad
Page 119 and 120: simulations for the hoop strain at
Page 121 and 122: 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: axial load (e.g. buried pipelines t
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 187 and 188: 14.25% in hoop strain and 23.5% in
Page 189 and 190: consideration for the selection of
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5.4 Methodology of Thermal Expansio
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Figure 5.1: Some preventive measure
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5.4.1 The Fundamentals of the Therm
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5.5 Analysis of Results 5.5.1 The t
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Thermal Output (strain ) 0.0002 0.0
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(Strain ,ε) Figure 5.12: Coefficie
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(Strain ,ε) 0.0002 0.00018 0.00016
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Table 5.1: The strain readings afte
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maximum shear strain increase as th
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The above results show that shear s
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shear strains becomes more stable a
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for future safe design and operatio
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has been fully cured. Poor surface
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6.3 Primary PhD Achievements The ea
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In Chapter 5, the CTE was determine
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ASM International (2002), "Thermal
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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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