Interface Cracking of FGM Coatings under Uniform Thermal Loading

2019 ◽  
pp. 388-396
Author(s):  
B. Yildirim ◽  
F. Erdogan
Keyword(s):  
Thermal Loading ◽  
Interface Cracking

scholarly journals The Design and Application of a Novel Duplex Coating Formed by Laser Pre-Treatment

2006 ◽  
Vol 118 ◽  
pp. 243-246 ◽  
Author(s):  
Kun Zhang ◽  
Chen Wu Wu ◽  
Ying Hu ◽  
Guang Nan Chen
Keyword(s):  
Stress State ◽  
Thermal Loading ◽  
Positive Response ◽  
Steel Substrate ◽  
Fem Modeling ◽  
Surface Cracking ◽  
Duplex Coating ◽  
Interface Cracking ◽  
Pre Treatment ◽  
Conventional Coating

novel duplex coating is presented on steel substrate by laser discrete quenching prior to chromium coating deposition. Due to the periodical changes in the mesostructures and properties of underlying substrate, the cracking and spalling behaviors of the duplex coating are expected to be different from that of conventional coating. A classic erosion experiment is selected to characterize the positive response of the duplex coating subjected to thermal loads. It is found that the surface cracking is partly restrained and the interface cracking is partly arrested. FEM modeling results show that a unique stress state is induced in the duplex coating with the tempering of the discrete pre-quenched regions due to thermal loading, which is believed to be the mechanism of controlling the damage modes.

Fracture-Tolerant and Shear-Resistant Interlayers for Mitigation of Reflective Cracking

2019 ◽  
Vol 2673 (10) ◽  
pp. 35-46
Author(s):  
Cristian Cocconcelli ◽  
Bongsuk Park ◽  
Jian Zou ◽  
George Lopp ◽  
Reynaldo Roque
Keyword(s):  
Asphalt Pavement ◽  
Aggregate Size ◽  
Cost Effective ◽  
Design Guidelines ◽  
Reflective Cracking ◽  
Rubber Membrane ◽  
Near Surface ◽  
Field Evidence ◽  
Cracking Performance ◽  
Interface Cracking

Reflective cracking is frequently reported as the most common distress affecting resurfaced pavements. An asphalt rubber membrane interlayer (ARMI) approach has been traditionally used in Florida to mitigate reflective cracking. However, recent field evidence has raised doubts about the effectiveness of the ARMI when placed near the surface, indicating questionable benefits to reflective cracking and increased instability rutting potential. The main purpose of this research was to develop guidelines for an effective alternative to the ARMI for mitigation of near-surface reflective cracking in overlays on asphalt pavement. Fourteen interlayer mixtures, covering three aggregate types widely used in Florida, and two nominal maximum aggregate sizes (NMAS) were designed according to key characteristics identified for mitigation of reflective cracking, that is, sufficient gradation coarseness and high asphalt content. The dominant aggregate size range—interstitial component (DASR-IC) model was used for the design of all mixture gradations. A composite specimen interface cracking (CSIC) test was employed to evaluate reflective cracking performance of interlayer systems. In addition, asphalt pavement analyzer (APA) tests were performed to determine whether the interlayer mixtures had sufficient rutting resistance. The results indicated that interlayer mixtures designed with lower compaction effort, reduced design air voids, and coarser gradation led to more cost-effective fracture-tolerant and shear-resistant (FTSR) interlayers. Therefore, preliminary design guidelines including minimum effective film thickness and maximum DASR porosity requirements were proposed for 9.5-mm NMAS (35 µm and 50%) and 4.75-mm NMAS FTSR mixtures (20 µm and 60%) to mitigate near-surface reflective cracking.

Random impact FEM simulation of irregularly-shaped media for parametric study of vibratory surface enhancement

2021 ◽  
pp. 095440542199012
Author(s):  
Jing Zhang ◽  
Joselito Yam Alcaraz ◽  
Swee-Hock Yeo ◽  
Arun Prasanth Nagalingam ◽  
Abhay Gopinath
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Parametric Study ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Fem Simulation ◽  
Surface Finishing ◽  
Aerospace Materials ◽  
Surface Enhancement ◽  
Steel Balls

Aerospace materials experience high levels of mechanical and thermal loading, high/low cycle fatigue, and damage from foreign objects during service, which can lead to premature retirement. Mechanical surface treatments of metallic components, for example, fan blades and blisks, are proven to improve fatigue life, improve wear resistance and avoid stress corrosion by introducing work hardening, compressive residual stresses of sub-surface, and surface finishing. Vibropeening can enhance aerospace materials’ fatigue life involving the kinetic agitation of hardened steel media in a vibratory finishing machine that induces compressive stresses into the component sub-layers while keeping a finished surface. Spherical steel balls are the most widely used shape among steel-based media and have been explored for decades. However, they are not always versatile, which cannot access deep grooves, sharp corners, and intricate profiles. Steel ballcones or satellites, when mixed with round steel balls and other steel media (diagonals, pins, eclipses, cones), works very well in such areas that ball-shaped media are unable to reach. However, a methodology of study the effect of irregularly-shaped media in surface enhancement processes has not been established. This paper proposes a finite element-based model to present a methodology for the parametric study of vibratory surface enhancement with irregularly-shaped media and investigates residual stress profiles within a treated area of an Inconel component. The methodology is discussed in detail, which involves a stochastic simulation of orientation, impact force, and impact location. The contrasting effects of a high aspect ratio, or an edge contact, as opposed to rounded and oblique contacts are demonstrated, with further analysis on the superposition of these effects. Finally, the simulation results are compared with actual residual stress measurements and was found to have a max percent difference of 34% up to 20 [Formula: see text]m below the media surface.

scholarly journals Mechanical Performance of a Ballastless Track System for the Railway Bridges of High-Speed Lines: Experimental and Numerical Study under Thermal Loading

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2876
Author(s):  
Yingying Zhang ◽  
Lingyu Zhou ◽  
Akim D. Mahunon ◽  
Guangchao Zhang ◽  
Xiusheng Peng ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Loading ◽  
Mechanical Performance ◽  
Track Structure ◽  
Box Girder ◽  
High Speed Railway ◽  
Ballastless Track ◽  
Track System ◽  
Girder Bridge ◽  
Track Slab

The mechanical performance of China Railway Track System type II (CRTS II) ballastless track suitable for High-Speed Railway (HSR) bridges is investigated in this project by testing a one-quarter-scaled three-span specimen under thermal loading. Stress analysis was performed both experimentally and numerically, via finite-element modeling in the latter case. The results showed that strains in the track slab, in the cement-emulsified asphalt (CA) mortar and in the track bed, increased nonlinearly with the temperature increase. In the longitudinal direction, the zero-displacement section between the track slab and the track bed was close to the 1/8L section of the beam, while the zero-displacement section between the track slab and the box girder bridge was close to the 3/8L section. The maximum values of the relative vertical displacement between the track bed and the bridge structure occurred in the section at three-quarters of the span. Numerical analysis showed that the lower the temperature, the larger the tensile stresses occurring in the different layers of the track structure, whereas the higher the temperature, the higher the relative displacement between the track system and the box girder bridge. Consequently, quantifying the stresses in the various components of the track structure resulting from sudden temperature drops and evaluating the relative displacements between the rails and the track bed resulting from high-temperature are helpful in the design of ballastless track structures for high-speed railway lines.

Generalized displacement correlation method for mechanical and thermal fracture of FGM

2020 ◽  
Vol 09 (01) ◽  
pp. 2050004
Author(s):  
Y. Ait Ferhat ◽  
A. Boulenouar ◽  
N. Benamara ◽  
L. Benabou
Keyword(s):  
Present Method ◽  
Thermal Loading ◽  
Parametric Design ◽  
Correlation Method ◽  
Functionally Graded ◽  
Mixed Mode Fracture ◽  
Graded Materials ◽  
Displacement Based ◽  
Ansys Parametric Design Language ◽  
Good Agreement

The main objective of this work is to present a numerical modeling of mixed-mode fracture in isotropic functionally graded materials (FGMs), under mechanical and thermal loading conditions. In this paper, the displacement-based method, termed the generalized displacement correlation (GDC) method, is investigated for estimating stress intensity factor (SIF). Using the ANSYS Parametric Design Language (APDL), the continuous variations of the material properties are incorporated by specified parameters at the centroid of each element. This paper presents various numerical examples in which the accuracy of the present method is verified. Comparisons have been made between the SIFs predicted by the GDC method and the available reference solutions in the current literature. A good agreement is achieved between the results of the GDC method and the reference solutions.

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