Parameterized Finite Element Modeling of the Surface Systems With Coatings Which Considers the Cracking of the Coatings and Influences of the Case-Hardening of the Substrate

Abstract

Accurately predicting the failure of multilayered surface systems, including coatings on tools or products, is of significance for all of the parties concerned within the chain of design, manufacturing and use of a product. Previous modeling work has, however, been focused largely on the effect of individual parameters rather than on the performance of a multilayered system as a whole. Design and manufacture of multilayered surface systems, currently, still relies largely on experiments and failure tests. A parameterized approach which considers geometrical, material, interfacial and loading variables, processing history, thermal effects, surface-failure modeling, etc. has therefore been developed to address the situation in order to be able to improve the efficiency and accuracy of the analysis and design of multilayered coating-systems. Material property values for the hardened case of the substrate are described with a function of the hardened depth and defined with a field method. Initial residual stresses calculated using a newly developed theoretical model are incorporated into the model as initial stress conditions. Thermo-mechanical coupled modeling is incorporated into the model so as to be able to consider temperature effects. These are associated with a cohesive-element modeling approach, which has been used to predict indentation-induced crack initiation and propagation within the coating layer. The comparison of experimental results with those of numerical modeling affords excellent agreement. The parameterized modeling method developed allows for the parameters to be changed easily during a series analysis. Combined with the capability of the prediction of cracking of the coatings, the developed method/model provides an efficient way for investigating the effects of these parameters on the behavior of multilayered systems, which is demonstrated by the analysis of three cases of the coated tool steels (H11): (i) a substrate without being pre-heat-treated; and (ii) two substrates with a shallow and a deep hardened-case, respectively, (both are treated by plasma-nitriding). The results showed that the case-hardening of a substrate has a significant influence on the performance of the surface system with coating, especially on its load-bearing capacity and the cracking of the coating.

Investigation of the initiation and propagation of cracks in the coated surface of spur gear: An application of irreversible cohesive zone model

“…Implementation of cohesive zone model in the between the continuum elements has been proved an efficient technique for the simulation of nucleation and propagation of cracks in the coating surface under monotonic loading [1]. However, under the fatigue loading condition, the deterioration of material properties and cohesive strength is expected to be related to the loading history.…”

“…By means of cohesive-zone modelling approach, the critical load in terms of the initiation of the first crack is able to be predicted. More details about the bilinear cohesive constitutive law, the implementation and applications can be found in [1].…”

“…Apparently, a comprehensive computational model, allowing for the specific working conditions to be taken into account, is demanded, from the point of the coating design and analysis of view. Most recently, an innovative modelling strategy, which combined with the parameterized modelling, submodelling technique and cohesive zone model (CZM), was developed to determine the load bearing capacity for the coated products [1,2]. The advantage of this comprehensive modelling technique allows for many key factors, including geometry, material MATEC Web of Conferences properties and pre-heated treatment to be considered for the coating design and its failure mechanism.…”

“…The advantage of this comprehensive modelling technique allows for many key factors, including geometry, material MATEC Web of Conferences properties and pre-heated treatment to be considered for the coating design and its failure mechanism. This modelling strategy has been validated by a series of micro-indentation test and rolling contact test [1,3]. In this study, the function of this innovative modelling strategy is further developed by implementation of the irreversible cohesive law with unloading-reloading hysteresis, with which the failure mechanisms of the coated spur gear under the contact fatigue loading will be investigated.…”

Investigation into initiation and propagation of cracks in the coated surfaces of spur gears with submodelling and irreversible cohesive-zone modelling techniques

“…Clearly, a more accurate computational model, allowing for the specific working conditions to be taken into account, is much needed from the point of view of the coating design and analysis. Most recently, an innovative modelling method, which combined with the parameterized modelling, submodelling technique and cohesive zone model (CZM), was developed to determine the load-bearing capacity for the coated products [6,7]. This comprehensive modelling method allows for many key factors, including geometry, material properties and pre-heated treatment, to be considered in the coating design and analysis.…”