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approaches (i.e. POD and POS) which rely on a single measurement taken at a particular point in time, with structural integrity monitoring (SIM), the continuous collection of data over a longer period of time is possible. The assessment process takes into account the stage of the lifetime of the structure which is being monitored and the S-N curve for the welded steel plate joint for example, is expressed as Log (N) = 11.705 – 3Log(S) and is plotted on a log-log scale as illustrated in Figure 2.6. Figure 2.6: Stress life curve and SIMdex limit setting after 130 000 cycles on a log scale (De Leeuw and Brennan, 2009) Brennan (2007) also presents several other case studies of stress monitoring in rail application and steel structures. According to him, a wireless and self-powered stress memory system is able to identify components which, by the nature of their history, are more likely to contain stress-related flaws. As explained earlier, the conventional POD and POS can only tell the existence, type, size of the flaw and location at any point in time but not give any indication of whether or not a flaw is likely to develop. Therefore, this type of memory system has the possibility to be explored further for pipeline structures and research works are required to prove the effectiveness of this system in continuous pipeline stress monitoring. 20
2.3.3 Reliability Analysis of Information Hallen et al. (2003) explain how the use of probabilistic condition assessment to evaluate the integrity condition of corroding pipelines is beneficial to the operator or owner of pipelines because the uncertainties associated with in-line inspection (ILI) tools, pipeline geometry, corrosion growth rate and others can be modelled and considered over any chosen time period. By using the structural reliability methods, the probability of failures can be determined for the entire pipeline. The target probabilities which are established either from the historic failure rates (Greenwood, 2002) or from risk criteria (ERSG Ltd., 2009), will allow the operator to formulate cost-effective strategies for the future safe design and operation of the pipelines as agreed by Britto et al. (2010). By referring to reliability criteria and risk factors, Kharionovski (2006) has demonstrated his established express method which yields approximate expectations for the remaining gas pipeline service life-span. In their approach to determine the actions that guarantee the safe operation and cost-effective maintenance of the corroded pipeline over its expected service life, Hallen et al. (2003) present how this comparison is carried out in order to assess the benefits of remedial actions such as conducting repairs, as illustrated in Figure 2.7. According to them, the time it takes the failure probability to exceed the target probability is assumed to be the remaining safe life of the pipeline and the time to the next inspection. Figure 2.8 shows the scheme used to investigate the relationship between composite repairs, maximum allowable operating pressure (MAOP), corrosion growth rate and remaining safe life of the assessed pipeline. From that figure, as the composite repairs increase, the corrosion rate will reduce and the remaining life will increase significantly. Figure 2.9 shows the relationship between composite repairs and re-inspection intervals. As the number of composite repair increases, the re-inspection interval will be longer. 21
Page 1: CRANFIELD UNIVERSITY MAHADI ABD MUR
Page 4 and 5: ABSTRACT One of the most common pro
Page 7 and 8: TABLE OF CONTENTS ABSTRACT ........
Page 9 and 10: 3.7.1 Introduction ................
Page 11: 5.6 Summary and Conclusions .......
Page 14 and 15: Figure 3.1: Schematic diagram of th
Page 16 and 17: Figure 5.4: The average temperature
Page 18 and 19: NOMENCLATURES ACFM Alternating Curr
Page 21 and 22: 1 INTRODUCTION One of the most comm
Page 23 and 24: 1.1 Objectives Knowing this backgro
Page 25 and 26: The methodology of this integrated
Page 27 and 28: Chapter 6 contains the summary and
Page 29 and 30: period of the major part of the exi
Page 31 and 32: Figure 2.2: Reported interest in de
Page 33 and 34: Figure 2.4: Dent damage caused by v
Page 35 and 36: presented current practices, recent
Page 37 and 38: Energy Workforce Sdn Bhd (2011) cla
Page 39: available provides real time detect
Page 43 and 44: Figure 2.9: Pipeline failure probab
Page 45 and 46: 2.3.3.1 NDT Reliability and POD cur
Page 47 and 48: increase in the yield limit of stee
Page 49 and 50: 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
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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
Page 117 and 118:
Where; The Stiffness matrix is trad
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simulations for the hoop strain at
Page 121 and 122:
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
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Hoop Stress (MPa) Figure 3.3: Hoop
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However, Frost (2008) and Alexander
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Table 3.17: Ratio of Axial Stress N
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axial load (e.g. buried pipelines t
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3.10 Numerical Strain Analysis of C
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Figure 3.36 shows the contours befo
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Stress Concentration Factor 2 1.8 1
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In fact, for Notch 40 with 18 plies
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this second approach (i.e. the expe
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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
Page 205 and 206:
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
Page 213 and 214:
for future safe design and operatio
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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
Page 235 and 236:
Tennyson, R. C. and Mufti, A. A. (2
Page 237 and 238:
Xue, L., Widera, G. E. O. and Sang,
Page 239 and 240:
General Technical Specifications: T
Page 241 and 242:
Photos of the Design and Build of t
Page 243 and 244:
Composite Installation Process usin
Page 245 and 246:
APPENDIX 3 - STRAIN GAUGE INSTALLAT
Page 247 and 248:
Figure 7: Mylar tape was stuck onto
Page 249 and 250:
Figure 19: Repeating the above proc
Page 251:
2) Electrical Insulation Test Resul
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