PSI - Issue 41

Ericha Dwi Wahyu Syah Putri et al. / Procedia Structural Integrity 41 (2022) 266–273 Putri et al. / Structural Integrity Procedia 00 (2022) 000 – 000

270

5

3.2. C-Ring Specimen C-Ring is a spring that provides tension on the bolt or vice versa. The tightened bolt will give stress to the C ring, the shape of the research specimen. The change usually examines the distortion of the C-rings in dimensional measurements of the inner diameter (ID), outer diameter (OD), gap width (GW), thickness, flatness, cylindricity, and roundness. They are measured using a coordinate measuring machine (CMM). It can help for tubes, rods, and short lateral rods and is usually bolted with constant elongation or load. The inner & outer diameter changes and the change in gap width come with undersize distortion. This method uses the ASTM G38 – 01 standard for making and using the C-Ring specimen see Fig. 5a) (Chu et al., 2019). This method is preferred to determine the susceptibility of alloys of various product forms to stress corrosion cracking. Prawoto et al. (2012) conducted experimental, computational, and analytical analyses to study the stress redistribution during stress corrosion cracking with a C Ring specimen. The results are the stress vs. displacement equation in ASTM can only be used carefully. As the crack propagates, the equation cannot be used even when considering the decrease in thickness. However, the crack's tip is so sharp that it is almost impossible to use normal continuum mechanics analytically (Prawoto et al., 2021). The stresses on the C-ring can be calculated using Equations 2 and 3: = − ∆ (2) ∆ = 2 4 (3) Where D is the outer diameter of the C-ring before stressing, D f is the outer diameter of the stressed C-ring, σ is the elastic stress, Δ is the change of D at the required stress, d is the mean diameter ( D - t ), t is the wall thickness, E is the elastic modulus, and Z is the correction factor for the curved beam. a. b.

Fig. 5. Illustration of C-ring specimen

3.3. Tensile Specimen

Tensile specimens for measuring tensile properties in the air are adapted to SCC. SCC testing methods with tensile specimens use ASTM G-49 standard (Cui et al., 2021). This testing can be subjected to a wide range of stress levels associated with elastic or plastic strain. Because the stress system is intended to be essentially uniaxial (except in the cast of notched specimens), special attention must be exercised in the construction of stressing frames to prevent or minimize bending or torsional stresses (Padekar et al., 2013). Fig. 6 shows tensile specimens on SCC testing methods. Specimens can be quantitatively stressed by a constant load, a constant strain, or an increased load or strain. The most versatile way to perform stress corrosion cracking tests with tensile tests loaded in the axial direction is the flexibility to choose the type and size of the specimen, the stress method, and the stress level (Karolczuk et al., 2020).