Analysis Of Spalling Research Articles

Hygro-thermo-mechanical analysis of spalling in concrete walls at high temperatures as a moving boundary problem

A mathematical model allowing coupled hygro-thermo-mechanical analysis of spalling in concrete walls at high temperatures by means of the moving boundary problem is presented. A simplified mechanical approach to account for effects of thermal stresses and pore pressure build-up on spalling is incorporated into the model. The numerical algorithm based on finite element discretization in space and the semi-implicit method for discretization in time is presented. The validity of the developed model is carefully examined by a comparison between the experimentally determined data stated in literature and the results obtained from the numerical simulation.

Analysis of Spalling in Roughing Mill Backup Rolls of Wide and Thin Strip Hot Rolling Process

In this paper, the spalling causes of backup rolls in a roughing mill of a hot strip rolling mill were investigated. The roughing mill withstood extreme service conditions with long service cycles for backup and work rolls, a large variety of the same width rolling campaigns, severe and non‐uniform wear contours of backup and work rolls. Analysis of cyclic stress applied on backup rolls indicated that contact stress played a dominant role in rolling contact fatigue which led to spalling on the backup roll surface. A 3D finite element model of roll system was established and contact stresses between rolls in whole service periods of backup and work rolls were calculated. The simulation results showed that roll wear had significant impact on contact stress distribution. In particular, the severe and non‐uniform U‐typed wear contours of work rolls led to produce huge contact stress peak in two sides of the rolls, where existed large cracks by eddy current inspection of post‐service backup rolls. Backup rolls stood thousands of times stress cycle in a service period, they were liable to fatigue damage in these areas. A new backup roll contour was developed to improve contact stress distribution and no spalling accidents were happened any longer after applied to the roughing mill.

An analysis of spalling in the microscratch test

An analysis of the microscratch test is presented for the case when extensive spalling occurs ahead of the scratch. In contrast to earlier models, attention is not focused on modeling the loads exerted on the film during a scratch test. Rather, the analysis relies on using the geometry of the spall to deduce the critical in-plane load for delamination and, hence, the interfacial toughness. It is shown that the extent of the spall is inversely proportional to the fourth root of the toughness. The model is used to compute the interfacial toughness between a Pt film and a NiO substrate using experimental data given in the literature. The predicted toughness is very consistent with the expected value.