relaxation modulus master curve of HDPE and long-term failure pressure of PSP with time

figure 4-Curve fitting to the test data of HDPE tensile relaxation modulus with time figure 4 is the relaxation modulus master curve of HDPE (trade mark YEM4803T). figure 8-Variation of long-term failure pressure with the elapsed time figure 8 shows the long-term failure pressure of a composite pipe (its name is plastic pipe reinforced by cross helically wound steel wires, and the type is DN200 PN1.6).