PSI - Issue 60

A. Bhardwaj et al. / Procedia Structural Integrity 60 (2024) 723–734 Abhimanyu Bhardwaj/ Structural Integrity Procedia 00 (2019) 000 – 000

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(b) Fig. 3 Design details of the job-carrier components. (a) Plates: The plates are designed based on plate theory, with a focus on meeting strength and rigidity requirements. Slots are strategically introduced in the plates to facilitate efficient radiation heat transfer, enable thermocouple placement, and achieve weight reduction for the entire assembly. (b) Stiffeners: Stiffeners are designed using strips instead of circular stiffeners made of TZM alloy for deformation reduction. This optimized design ensures that the plates effectively withstand the applied loads, exhibit sufficient rigidity, and meet the required safety margins for reliable performance within the furnace's operating conditions. Stiffeners play a crucial role in minimizing stresses and deformations. According to plate theory, circular-shaped stiffeners, when placed on the bottom of a circular plate at the region of highest slope of deflection, yield maximum reduction in stress and deformation. However, in our present case, designing circular stiffeners through machining would result in substantial wastage of expensive TZM alloy. To optimize material usage, strips are employed as stiffeners, strategically tracing the circular path, as illustrated in Fig. 2 and 3 (b). In addition to the strip stiffeners, an extra U rail stiffener is also incorporated in the job-carrier design to further enhance the structure's integrity, as illustrated in Fig. 2. This combination of stiffener types ensures an efficient distribution of loads and reinforces critical areas, The design of U-rail columns takes into account both buckling and direct stresses as potential failure modes. To assess buckling, we employed Euler beam theory with a conservative approach, assuming a fixed-free boundary condition. The load ( P ) of 100 kg was applied to compute moment of inertia ( I ) and subsequently dimensions of the U-section using Eq. (3), considering elastic modulus ( E ), and column length ( l ). For buckling calculation, factor of safety of four is used. Stress basis calculation were carried out, considering a load of 100 kg applied at an eccentricity of 0.250 m. Eq. (4) was used to compute moment of inertia ( I ) and area ( A ) to subsequently compute dimensions of the U-section considering load ( P ), allowable stress ( S ), applied moment ( M ) ,and maximum distance from the neutral axis ( d ). By incorporating both buckling and direct stress calculations, we arrived at the final design for the U-rail columns, as illustrated in Fig. 4 (a). The design of cotter pins is focused on their resistance against shear failure, considering a load of 100 kg applied on each column. To determine the suitable dimensions from bolt area ( A ), we employed Eq. (5) based on applied load ( P ) and allowable stress ( S ). The design, as depicted in Fig. 4 (b), incorporates the calculated dimensions to ensure the cotter pins' integrity in their shear resistance capacity. = 2 4 2 (3) = + (4) resulting in a well-supported job-carrier. 2.2. Design of Columns and Cotter Pins