Integral Finite Element Analysis Research Articles

Experimental and numerical study on the residual seismic performance of post-blast RC piers

Experimental and numerical study on the residual seismic performance of post-blast RC piers

Full-field experimental and numerical characterisation of a growing fatigue crack in a stainless steel

Abstract Full-field mechanical characterisation has been carried out for growing cracks under cyclic loading conditions using both Digital Image Correlation (DIC) and integrated finite element (FE) analysis. Compact tension specimens of a model material, stainless steel 316L, were used in the experiments, where the position of the crack tip and the evolution of the near-tip displacements and strains were tracked at selected observation points along the crack path. “Critical” strains at the advancing crack tip were captured at selected locations along the crack path. The influence of DIC data processing strategies and the choice of a characteristic length on the critical strain were examined. Potential attenuation effects behind the crack tip, commonly referred to as crack closure, were also investigated by evaluating the crack opening displacement (COD) at selected instances to the crack tip during the crack growth, where the experiment was interrupted to allow DIC measurements taken during a complete cycle. The impact of measured crack closure on the near-tip strains and crack driving force in terms of J-integral was assessed using both standard and integrated FE analysis.

A 3D full‐field study of cracks in a nuclear graphite under mode I and mode II cyclic dwell loading conditions

AbstractThree‐dimensional (3D) full‐field deformation around crack tips in a nuclear graphite has been studied under mode I and mode II cyclic dwell loading conditions using digital volume correlation (DVC) and integrated finite element (FE) analysis. A cracked Brazilian disk specimen of Gilsocarbon graphite was tested at selected loading angles to achieve mode I and mode II cyclic dwell loading conditions. Integrated FE analysis was carried out with the 3D displacement fields measured by DVC injected into the FE model, from which the crack driving force J‐integral was obtained using a damaged plasticity material model. The evolution of near‐tip strains and the J‐integral during the cyclic dwell loading was examined. Under cyclic dwell, residual strain accumulation was observed for the first time. The results shed some light on the effect of dwell time on the 3D crack deformation and crack driving force in Gilsocarbon under cyclic mode I and II loading conditions.

Characterisation of fatigue crack tip field in the presence of significant plasticity

Characterisation of a fatigue crack tip in the presence of significant plasticity has been challenging due to the lack of suitable tools and lack of knowledge of material constitutive information under cyclic loading. In this paper, Digital Image Correlation (DIC) and integrated finite element (FE) analyses have been used to characterise the crack-tip field beyond the small-scale yielding (SSY) regime in a stainless steel 316L of a compact-tension (CT) specimen under mode I loading conditions. The non-linear characteristics of the near-tip deformation field were verified by the poor fit to the William’s regression and the overestimation of the stress intensity factor K. The extent of the crack tip plasticity was estimated using a detailed constitutive material model and compared with the estimated by Irwin. The displacement fields local to a stationary fatigue crack were mapped using DIC, and inputted into the FE model as boundary conditions so that an integrated FE analysis was carried out. Fatigue pre-cracking was simulated in the FE analysis prior to the full-field analysis of the fatigue crack tip, including stress/strain distributions ahead of the crack tip and the crack opening displacement (COD) under selected loading conditions. Although a distinct “knee” was captured as an indication of crack opening from the compliance curves in both the DIC measurements and the FE analyses, consistent with the existing knowledge on the phenomenon of crack closure, it does not appear to correlate with the crack driving force measured by the J-integral.

Finite Element Analysis on the Fatigue Stresses of a Railway Vehicle Roller Bearing

The distributed fatigue stresses of 353130B roller bearing of China freight car with K5 type titling bogie are investigated using an elastic-plastic finite element (FE) analysis. Policy of two steps is applied. First, an integral FE analysis is performed on adapter-bearing-axle-wheel-track interactive system. Second, local analysis is applied to the local axle-bearing-adapter part, in which on the section of axle is with the bound condition obtained from the integral analysis. Wheel contact force spectrum on a curved railway line by on-line inspection is used for the present study. Previous proposed multivariate quadratic regression approach is applied for transferring the load spectrum to the dynamic stress spectrum at a special position of the bearing. Results reveal that the rollers, innerand outer-rings of bearing are subjected to distribute axially equivalent stress amplitude. The closer to axle side, the larger the equivalent stress amplitude. The equivalent stress amplitude of outer ring at the position close to the seal seat is relative larger to that of inner ring. The results are consistency with the shell failures of the bearings in production. Availability of present study is indicated.