PSI - Issue 42

James C. Hastie et al. / Procedia Structural Integrity 42 (2022) 614–622 J.C. Hastie et al. / Structural Integrity Procedia 00 (2019) 000–000

618

5

2 = � 1 � 2

(5b)

Matrix in tension (( σ 2 + σ 3 ) > 0):

2 = ( 2 + 3 ) 2 2 + � 22 3 – 2 3 � 2 + � 12 2 + 12 3 � 2

(5c)

Matrix in compression (( σ 2 + σ 3 ) < 0):

2 = �� 2 � 2 – 1 � ( 2 + 3 ) + ( 2 + 3 ) 2 4 2 + � 22 3 – 2 3 � 2 + � 12 2 + 12 3 � 2

(5d)

We note that the above are squares of the failure indices. The strength ratio based on Hashin is = 1 ( , , , ) 3. Results and discussion 3.1. Riser operation We begin by examining the temperature distributions through the pipe wall for low and high internal operating temperatures. Distributions for T i = 30 °C and 130 °C combined with T ∞ = 5 °C, h c = 50 Wm -2 °C -1 on the outer surface are shown in Fig. 4 (distributions are the same for all configurations since they only differ in fibre angle rotated about the radial direction). Temperature at the outer surface exposed to free convection does not rise significantly with T i . The drop in temperature is steeper through the liners (radius, r = 76 mm to 84 mm and 92 mm to 100 mm) than the composite laminate ( r = 84 mm to 92 mm) as a result of lower through-liner thermal conductivity and thus greater insulating characteristics. (6)

Fig. 4. Through-wall operating temperature distribution

The failure response of the configurations subjected to operating load combinations is now investigated. Layer strength ratios are summarised in Table 2 for the above temperature profiles combined with the following mechanical loads: P i = 15 MPa, P e = 10 MPa, F z = 50 kN. The increase in internal temperature causes a substantial drop in strength ratio for the inner liner of all configurations. The laminate and outer liner are less affected, which follows less temperature change seen in Fig. 4. Given that the inner liner function is fluid containment, yielding does