Aging degradation of mechanical structures

Abstract

A numerical approach is proposed in this paper for safety assessment of mechanical structures with agerelated degradation. Deterioration occurs in mechanical structures due to various environmental attacks and operation conditions which leads to changes in structural performance and structural resistance capacity. By combining techniques such as degradation evaluation methods, damage mechanics, and the finite element method, the proposed numerical method can be used to analyse the responses and damages of mechanical structures with age-related degradation. Ageing degradation effects can be taken into account by introducing degradation factor into formulations of finite element method and damage mechanics. The numerical results for a notched bar and a plate with a central hole are provided to validate the proposed numerical method.

Future of nanoindentation in archaeometry

“…Potentially, the instrumented indentation technique can be used to quantify the residual stresses of materials [19,64], which is known to affect fatigue strength, fracture toughness and wear resistance, and which can influence the structural strength and lifetime of archaeological components. This review concludes that many investigations above scrutinise Aging is a time-dependent process [67] and one of the important aspects in archaeometry. Aging (in the current context, for example, due to low or high temperature exposure, mechanical loading, radiation exposure, actions of insects, bacteria and fungi, tribological wear, etc.)…”

“…Aging (in the current context, for example, due to low or high temperature exposure, mechanical loading, radiation exposure, actions of insects, bacteria and fungi, tribological wear, etc.) can be explained as partial or total loss of their capacity to achieve the purpose, can lead to change in structural properties, and may impact the ability to withstand various challenges from operation, environment and natural events [67]. Except few examples, such as ultraviolet irradiation and the actions of insects, bacteria and fungi related degradation in skin [6], age-related variations at grain boundaries in metals [7], tribological wear of enamels [13][14], mechanical (ductility) properties for paint like materials [16], radiation related damage in stones [20], aging related characterization of archaeological materials using nanoindentation technique has not been demonstrated much through literature.…”

Seismic vulnerability of reinforced concrete buildings considering aging and soil-structure interaction effects

“…Common problems to concrete material may include alkali-aggregate reaction, freezing and thawing, leaching, sulphate attack, cracking due volume changes led by temperature variation, corrosion of concrete, debonding of steel. Cracking, splitting, spalling and disintegration, loss of mortar and stones are common defects occurring in masonry structures due to aging (Valliappan and Chee, 2008). Aging effects as a consequence of chemical, physical and environmental attacks (e.g.…”