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3.7.3 Internal Pressure For a pipe under internal pressure, the hoop stress, h , and the axial stress, a are the two major stress components that are always considered. In this FE model, the maximum hoop and axial stresses were taken at the notch root and nominal hoop and axial stresses were taken at the point away from the defect (refer to Figure 3.5) which gives the stress concentration factor, K t , by h Kt h max h nom a max a (Equation 3.5) and Kt a 82 nom (Equation 3.6) The problem of SCF for circumferentially notched pipe has been examined by several authors (Carpinteri et al., 2004), yet a study on an arc-shaped notch in a pipe has not been carried out so far. The outer radius of the external notch is difficult to obtain because of the nature of its geometry and this makes comparison against other types of notches (e.g. those given by Pilkey (1997)) impractical. Prior to making experimental measurements, confidence can be attributed to the current FEA by considering the results of the parametric variations and using engineering experience and judgment. Convergence tests were carried out on all notch geometries, as represented in Table 3.4 and Figures 3.16 and 3.17. These show that all the convergence results of stress concentration factors are based on both hoop and axial stresses as the number of elements increases and the size of the elements becomes smaller.
Table 3.4: Convergence tests on various sizes of notch; Test Pressure at 50 bar No of Elements h max h nom h K t 83 a max a nom Relative Notch, L/t = 0.85 (N7); Arc-shaped (semi-circle) Notch a K t 4576 90.86 62.61 1.45 55.45 15.44 3.59 5120 90.94 61.36 1.48 55.65 15.37 3.62 11872 90.86 61.23 1.48 55.47 15.51 3.57 14000 90.82 61.25 1.48 55.33 15.63 3.54 Relative Notch, L/t = 4.88 (N40); Arc-shaped Notch 4454 98.04 66.86 1.61 48.69 17.80 2.73 6800 98.94 60.99 1.62 49.94 17.69 2.82 11664 100.73 61.01 1.65 56.21 17.95 3.13 14504 100.74 60.90 1.66 56.18 17.73 3.17 Relative Notch, L/t = 7.32 (N60); Arc-shaped Notch 3840 104.98 61.76 1.70 50.05 19.46 2.57 7200 105.04 61.82 1.70 48.91 19.32 2.53 11520 105.07 61.59 1.71 48.54 19.86 2.44 14190 105.08 61.75 1.70 48.31 19.77 2.44 Relative Notch, L/t = 10.98 (N90); Arc-shaped Notch 3840 107.88 61.49 1.75 42.89 22.53 1.90 7200 107.31 61.47 1.75 41.34 22.36 1.85 11520 107.17 61.21 1.75 40.91 22.33 1.83 14448 107.14 61.15 1.75 40.78 22.35 1.83 Relative Notch, L/t = 12.20 (N100); Arc-shaped Notch 3936 108.17 61.17 1.77 40.79 23.65 1.72 7200 107.29 61.08 1.76 39.22 23.43 1.67 11520 107.10 60.81 1.76 38.80 23.40 1.66 14448 107.10 60.75 1.76 38.68 23.42 1.65
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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
Page 51 and 52: Manufacturers such as Walkers Techn
Page 53 and 54: Company L.P, 2005); Aquawrap ® pro
Page 55 and 56: monitoring, inspection, and damage
Page 57 and 58: 2.6.2 Aims of Structural Health Mon
Page 59 and 60: Figure 2.16: Application fields and
Page 61 and 62: egistered by the piezoelectric sens
Page 63 and 64: discretization error. Round-off err
Page 65 and 66: notches and Neuber‘s is better fo
Page 67 and 68: maximum local stress at discontinui
Page 69 and 70: De Carvalho (2005) concludes that t
Page 71 and 72: accurate simulation of loading espe
Page 73 and 74: Based on the above facts, the opera
Page 75 and 76: 3 FINITE ELEMENT ANALYSIS (FEA) IN
Page 77 and 78: Figure 3.2: Schematic diagram of th
Page 79 and 80: In this modelling work (i.e. compos
Page 81 and 82: This partition toolset also helps u
Page 83 and 84: Figure 3.6: Mesh control using Swee
Page 85 and 86: Figure 3.7: Schematic representatio
Page 87 and 88: 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: One of the contributions of this st
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 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
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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
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welded weld neck flange at both end
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Figure 4.7: Sensor and heating elem
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Figure 4.9: A summary of data acqui
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One of the objectives of doing this
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Figure 4.14: A schematic diagram of
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Table 4.1: Strain gauge readings at
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microstrain 3.00E-04 2.50E-04 2.00E
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However, the axial load transfer is
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Mircostrain 500 450 400 350 300 250
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Since the defect is not a flat notc
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Again, the epoxy resin plays a sign
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Table 4.4: Study at the defect area
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Mircostrain 300 250 200 150 100 50
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Mircostrain 600 500 400 300 200 100
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14.25% in hoop strain and 23.5% in
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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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