The present work deals with the development of a finite element methodology for obtaining the stress distributions in thick cylindrical HK40 stainless steel pipe that carries high-temperature fluids. The material properties and loading were assumed to be random variables. Thermal stresses that are generated along radial, axial, and tangential directions are generally computed using very complex analytical expressions. To circumvent such an issue, probability theory and mathematical statistics have been applied to many engineering problems, which allows determination of the safety both quantitatively and objectively based on the concepts of reliability. Monte Carlo simulation methodology is used to study the probabilistic characteristics of thermal stresses, and was implemented to estimate the probabilistic distributions of stresses against the variations arising due to material properties and load. A 2-D probabilistic finite element code was developed in MATLAB, and the deterministic solution was compared with ABAQUS solutions. The values of stresses obtained from the variation of elastic modulus were found to be low compared to the case where the load alone was varying. The probability of failure of the pipe structure was predicted against the variations in internal pressure and thermal gradient. These finite element framework developments are useful for the life estimation of piping structures in high-temperature applications and for the subsequent quantification of the uncertainties in loading and material properties.
Laser forming or laser bending is a newly developed, flexible technique which modifies the curvature of sheet metal by thermal residual stresses instead of external forces. The process is influenced by many parameters such as laser parameters, material properties, and target dimensions. In this work, a pulsed Nd:YLF laser was used as the energy source. The laser beam was focused into a line shape irradiating on the stainless steel specimen to induce bending. The bending angle was measured at various processing conditions. A finite element analysis was performed with the use of a two-dimensional plane strain model to calculate the thermoelastoplastic deformation process. Experimental measurements and computational results were in good agreement. Numerical sensitivity studies were performed to evaluate the effects of the unavailable material property data at high temperature. It was found that both optical reflectivity and thermal expansion coefficient influenced the bending angle significantly, while other extrapolated material properties at high temperature yielded acceptable results.
The present work deals with the development of finite element methodology for obtaining the stress distributions in thick cylindrical HK40 stainless steel pipe that carry high temperature fluids. The material properties and loading are assumed to be random variables. Thermal stresses that are generated along radial, axial and tangential directions are computed generally using analytical expressions which are very complex. To circumvent such an issue, the probability theory and mathematical statistics have been applied to many engineering problems which allows to determine the safety both quantitatively and objectively based on the concepts of reliability. Monte Carlo simulation methodology is used to study the probabilistic characteristics of thermal stresses which is used for estimating the probabilistic distributions of stresses against the variations arising due to material properties and load. A 2-D Probabilistic finite element code is developed in MATLAB and the deterministic solution is compared with ABAQUS solutions. The values of stresses that are obtained from the variation of elastic modulus are found to be low as compared to the case where the load alone is varying. The probability of failure of the pipe structure is predicted against the variations in internal pressure and thermal gradient. These finite element framework developments are useful for the life estimation of piping structures in high temperature applications and subsequently quantifying the uncertainties in loading and material properties.
Abstract
WAUKESHA METAL NO. 88 is a corrosion resistant nickel-base alloy compounded to run against stainless steel without galling or seizing. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: Ni-84. Producer or source: Waukesha Foundry Company. Originally published July 1963, revised February 1993.
Abstract
Type HW is a nickel-base alloy containing chromium and iron. It is austenitic, non-magnetic, and has exceptionally high resistance to corrosion, cyclic heating, and oxidation. It is of the 60 Ni-12Cr type alloy. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Ni-37. Producer or source: Stainless steel foundries. Revised as Alloy Digest Ni-449, April 1994.
Abstract
ATI 441 is a low-carbon and low-nitrogen ferritic stainless steel with 18 Cr and columbium. The alloy is typically used for exhaust system components. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: SS-1150. Producer or source: Allegheny Technologies Inc..
Abstract
ATI 409HP (UNS S40900) ferritic stainless steel was introduced by ATI Allegheny Ludlum to provide improved oxidation and corrosion resistance for automotive exhaust systems in comparison to carbon steel. The alloy was designated "MF-1", indicating its end use: automotive mufflers. The good fabricability of this alloy, combined with its basic corrosion resistance and economy have significantly broadened the utility of ATI 409HP stainless steel. ATI 409HP consists of four grades: UNS S40900, S40910, S40920, and S40930. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, machining, and joining. Filing Code: SS-1135. Producer or source: Allegheny Technologies Inc..
Abstract
Böhler (or Boehler) A911 is a super duplex ferritic-austenitic chromium-nickel-molybdenum stainless steel with excellent resistance to stress-corrosion cracking, pitting, and crevice corrosion. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-1119. Producer or source: Böhler-Uddeholm Specialty Metals Inc..
Abstract
Nirosta 4429 is a low-carbon, high-nitrogen version of type 316 stainless steel. The low carbon imparts intergranular corrosion resistance while the nitrogen imparts both higher strength and some increased pitting corrosion resistance. It is recommended for use as welded parts that need not or cannot be annealed after welding. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, and joining. Filing Code: SS-787. Producer or source: ThyssenKrupp Nirosta.
Probability Study on the Thermal Stress Distribution in Thick HK40 Stainless Steel Pipe Using Finite Element Method
