Bounded Elastic Moduli Multiplier Technique for Limit Loads: Part 2 - Case Studies

An accompanying paper provides the theoretical underpinnings of a new method to determine statically admissible stress distributions in a structure, called Bounded elastic moduli multiplier technique (BEMMT). It has been shown that, for textbook cases such as thick cylinder, beam, etc., the proposed method offers statically admissible stress distributions better than the power law and closer to elastic-plastic solutions. This paper offers several examples to demonstrate the robustness of this method. Upper and lower bound limit loads are calculated using iterative elastic analyses using both power law and BEMMT. These results are compared with the ones obtained from elastic-plastic FEA. Consistently BEMMT has outperformed power law when it comes to estimating lower bound limit loads.

Thermal Stresses Due to Non-Uniform Internal Heat Generation in Functionally Graded Hollow Cylinder

Thermal stresses of a functionally graded hollow thick cylinder due to non-uniform internal heat generation are studied in this paper. Analytical solutions are obtained with radially varying properties by using the theory of elasticity. Thermal stresses distribution for different values of the powers of the module of elasticity and varying power law index of heat generation are studied. The results have been computed numerically and illustrated graphically.

A Prediction Model of the Concrete Cracking Induced by the Non-Uniform Corrosion of the Steel Reinforcement

This paper investigates the influence of non-uniform corrosion in the transversal direction of the steel reinforcement on the cracking propagation of the concrete cover. An analytical model is proposed for the prediction of the corrosion-induced cracking performance. Both the thick cylinder theory of the concrete and the effect of transversal non-uniform corrosion of the steel reinforcement are involved by considering the corrosion layer of the corrosion products and a layer of concrete with the corrosion products filled with the pores. A three-stage corrosion-induced cracking of the concrete is proposed: corrosion without expansive stress to the concrete, corrosion with expansive stress to the adjacent concrete, as well as the corrosion-induced cracking of the concrete. By considering the non-uniform corrosion of the steel reinforcement and the tensile stress induced by the volumetric expansion of the corrosion products, the cracking initiation resulting from the non-uniform corrosion was involved in the prediction model. The models were also validated by the experimental results from both the corroded specimens and the existing literature, which would be helpful for the evaluation of the existing reinforced concrete constructions in the marine environment.

Effect of Process Conditions on Residual Stress in Laser-MAG Welding of High Strength Steel

In this paper, the finite element method is used to simulate and analyze the laser-MAG composite welding of 4mm thick cylinder of high strength steel 30CrMnSiA, and the variation law of welding residual stress under different technological conditions is obtained. By comparing and analyzing the welding residual stress of the actual test plate by blind hole method with theoretical calculation value, the two methods are in good agreement, and the rationality of the model is verified.

Damage Evaluation of Grade 91 Thick Cylinder Under Variable Thermal Cyclic Loading Using Continuum Damage Coupled Viscoplastic Models

This study evaluates creep-fatigue damage in the modified Grade 91 thick-cylinder tested by Japan Atomic Energy Agency (JAEA), to understand the failure mechanism of critical components of Fast Reactor nuclear plants. As modified Grade 91 demonstrated creep-fatigue interaction induced failure mechanisms, finite element analysis of high-temperature components will require a unified constitutive model (UCM) that can simulate various creep-fatigue responses with reasonable accuracy. Hence, a UCM coupled with various advanced modeling features including the continuum damage modeling features is investigated to demonstrate their predictability of the fatigue, creep and creep-fatigue responses of the modified Grade 91 steel. The modified UCM is implemented into ABAQUS for analysis of creep deformation in the thick cylinder benchmark problem. Finite element analysis results are presented to demonstrate how the thermal cycling influences the creep-deformation of this high-temperature component. It is also demonstrated how thermal cycling’s influence on fatigue life can be determined based on the damage variable incorporated in the UCM.