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(Strain ) Table 5.4: The analysis of results after the 8th layer (at the defect area) Temperature (°C) ε1 ε2 22 0.0003 0.00025 0.0002 0.00015 0.0001 0.00005 188 Max Shear Strain (2R) Θ in radians 24 0 0 0 0 0 25 8.14E-05 -5.56E-05 1.37E-04 1.37E-04 -25.38 26 9.25E-05 -4.58E-05 1.38E-04 1.38E-04 -41.87 27 1.18E-04 -4.25E-05 1.59E-04 1.60E-04 -40.69 28 1.38E-04 -3.97E-05 1.76E-04 1.78E-04 -40.61 29 1.50E-04 -3.10E-05 1.79E-04 1.81E-04 -40.22 30 1.62E-04 -2.04E-05 1.79E-04 1.82E-04 -39.60 31 1.79E-04 -9.84E-06 1.85E-04 1.89E-04 -39.17 32 1.87E-04 3.53E-06 1.81E-04 1.84E-04 -39.64 33 1.99E-04 1.47E-05 1.82E-04 1.84E-04 -40.14 34 2.12E-04 2.47E-05 1.83E-04 1.87E-04 -38.80 35 2.21E-04 3.35E-05 1.83E-04 1.87E-04 -38.5 36 2.34E-04 5.03E-05 1.77E-04 1.84E-04 -37.07 37 2.46E-04 5.55E-05 1.83E-04 1.90E-04 -24.86 38 2.57E-04 6.34E-05 1.87E-04 1.93E-04 -27.13 39 2.66E-04 8.02E-05 1.81E-04 1.85E-04 -24.98 40 2.75E-04 9.60E-05 1.72E-04 1.79E-04 32.53 0 Figure 5.15: The effects of shear strain with the increasing temperature in the eight layers at the defect area 0 20 40 60 ε1 (Maximum Strain - Equation 5-6) ε22 (Maximum strain in transverse direction) Max Shear Strain (2R) - From Equation 5-4 Shear Strain (γ22) - From Equation 5-3 (Temperature °C)
The above results show that shear strain between laminates is solely induced by temperature variations. However, before these laminates are induced by any external factors, in this case temperature, Billoet and Cherouat (1999) mention that the woven fabrics which are impregnated with resin actually already have complex internal microstructures and present anisotropic behaviour due to the directions of the fibres. In this study, when this anisotropic composite is subjected to temperature variations, according to Schwarz et al. (1991) the expansion behaviour of the fibre composites is then determined by fibre expansivity, the fibre arrangement and the matrix. In fact, there are two main factors responsible for the thermal expansion of composites. The first is the thermal expansion of the fibre itself and the second is the contribution resulting from the internal shear stresses which are a function of the fibre angle, the ratio of the moduli of fibre and matrix, and of the fibre anisotropy. Schwarz et al. (1991) also mention that the effect of internal stresses is much greater, often resulting from a higher fibre modulus of elasticity. For example, carbon fibre that has a high modulus of elasticity does not only have high internal shear stress but also high internal shear strain. In Harding and Li's (1992) research in the determination of interlaminar shear strength for glass epoxy and carbon epoxy laminates at impact rates of strain, they found that the interlaminar shear stress is directly proportional to the average interlaminar shear strain. Therefore, it can be concluded here that measuring the CTE of composite at different layers, as referred to in Figure 5.12, is more practical for glass epoxy than the carbon epoxy composite. This is because using carbon fibre which has a higher fibre modulus and internal shear stress and strain than glass fibre would then lead to greater errors. The detailed study of shear behaviour of woven composite fabrics such as shear force, shear angle and shear rate can be referred to in Wang et al. (2006). They have developed a predictive model of shear behaviour of textile composites to replace time consuming material characterisation tests. Lee et al. (1990) also present the same study but use bias-extension tests instead. They have managed to show how the shear angle properties of glass fabrics are determined and predicted when subjected to tensile bias testing. According to them, there are three main methods to determine shear angle. The 189
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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
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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
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
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: maximum shear strain increase as th
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
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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