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(12.58%) and strain (16.9%) concentration factors respectively. At N60 and N90, both hoop stress and strain concentration factors are almost the same with a difference of only 1.86% and 1.2% respectively. At N100, hoop strain concentration has a greater reduction, i.e. of about 11%, than the hoop stress concentration factor. N7 shows the hoop stress concentration factor is 50% higher than the hoop strain concentration factor. Reduction of SCF (%) 18 16 14 12 10 8 6 4 2 0 N7 N40 N60 N90 N100 Figure 3.37: Reduction after the repair in hoop stress and strain concentration factors Figure 3.38 shows several line curves of stress and strain concentration factors with and without repair. Since strain concentration factor Kε and stress concentration factor Kσ are widely used in estimating the fatigue life of a notched body, it is important to relate these two factors together. Polak (1983) reports that if stresses and strains obey Hooke‘s law, both factors are equal to the theoretical stress concentration factor Kt and this relationship is expressed as; Kσ Kε = Kt 2 (Equation 3.22) 124 Hoop strain concentration factor Hoop stress concentration factor Length of Notch (mm)
Stress Concentration Factor 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 Ktwr = 1.33 Ktr = 1.19 Figure 3.8: Theoretical Stress Concentration Factors (with and without repair) If the theoretical concentration factor with repair (Ktr) for a particular notch is known, for example for N40, Ktr is equal to 1.35, and a hoop or axial strain concentration factor is obtained experimentally, then the hoop or axial stress concentration can be determined easily. From Figure 3.38 also, it can be seen that hoop stress and strain concentration factors without repair are not really uniform or close to each other if compared to hoop stress and strain concentration factors with repair that are closer to each other as the notch length increases and they steadily converge at notch length equals 100 mm. Ktwr = 1.58 Ktr = 1.35 7 40 60 90 100 3.11 Summary and Conclusions Ktwr = 1.67 Ktwr = 1.81 Ktr = 1.47 The convergence study is important to be carried out on the FE model before any other studies, such as the influence of pressure, stress concentration factors and others, can be carried out. It is necessary and beneficial to make a comparison study on 125 Ktr = 1.57 Ktwr = 1.77 Ktr = 1.61 Hoop Stress Concentration Factor without repair Theoretical Stress Concentration Factor (without repair)- Ktwr Hoop Strain Concentration Factor without repair Hoop Stress Concentration Factor with repair Theoretical Stress Concentration Factor (with repair) - Ktr Hoop Strain Concentration Factor with repair Notch Length (mm)
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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
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 and 140: axial load (e.g. buried pipelines t
Page 141 and 142: 3.10 Numerical Strain Analysis of C
Page 143: Figure 3.36 shows the contours befo
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
Page 191 and 192: 5.4 Methodology of Thermal Expansio
Page 193 and 194: 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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