scholarly journals Crack behaviour at the interface of a surface layer applied on a steel substrate by laser cladding

2021 ◽  
Vol 1209 (1) ◽  
pp. 012049
Author(s):  
L Malíková ◽  
P Doubek ◽  
P Miarka ◽  
S Seitl
Keyword(s):  
Surface Layer ◽  
Laser Cladding ◽  
Steel Substrate ◽  
Protective Layer ◽  
Cobalt Alloys ◽  
Material Interface ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Proper Material ◽  
Special Case

Abstract An influence of the bi-material interface between a steel substrate and a thin protective layer applied through laser cladding was investigated. A range of elastic properties and thicknesses of the layer were considered to cover the behaviour of a short crack in the selected materials such as bronze, nickel or cobalt alloys. The special case of the crack terminating directly at the interface was investigated, which is connected to the necessity of application of generalized approaches of linear elastic fracture mechanics. The results contribute to better understanding of fracture response of selected materials and to a more reliable decision on choosing a proper material of the protective layer.

scholarly journals Adhesion on Nanoorganized Multilayers

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Yolla Kazzi ◽  
Houssein Awada
Keyword(s):  
Surface Layer ◽  
Fracture Mechanics ◽  
Power Law ◽  
Contact Time ◽  
Linear Elastic Fracture Mechanics ◽  
Metallic Gold ◽  
Thin Surface Layer ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Glass Plates

Nanostructured multilayers composed of alternate organic (alkyldithiol) and metallic (gold) layers are grafted onto glass plates and prepared in order to modify the mechanical and local dissipative properties of a thin surface layer of the substrate. The adhesion phenomenon between a polyisoprene elastomer and these layers is presented and verified by two theories, namely, Johnson, Kendall, Roberts (JKR) and linear elastic fracture mechanics. The increase in adhesion with contact time following a power law has been clearly noted.

Case Study of Crack Initiation from Bi-Material Notches

2010 ◽  
Vol 452-453 ◽  
pp. 449-452
Author(s):  
Jan Klusák ◽  
Zdeněk Knésl
Keyword(s):  
Crack Initiation ◽  
Stress Singularity ◽  
Homogeneous Material ◽  
Material Interface ◽  
Damage Initiation ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
The Stability ◽  
Applied Stresses

Conditions of damage initiation in bi-material structures are analysed in the paper. The considerations are derived from the knowledge of the stress state caused by the existence of the sharp notch and the bi-material interface. The step change of material properties and the geometrical discontinuity at the interface leads to a singular peak of stress that is similar to the stress singularity near the crack tip in homogeneous material. That fact urges to use generalized linear elastic fracture mechanics for assessment of conditions of crack initiation. In the paper crack initiation direction and quantification of the external load connected with crack initiation are discussed. Within the stability assessment, possible directions of crack initiation should be considered and tested in both material components and at their interface as well. Knowing the critical applied stresses, one can decide among the damage eventualities.

Crack Behaviour in Laminar Ceramics with Strong Interfaces

2009 ◽  
Vol 417-418 ◽  
pp. 301-304 ◽  
Author(s):  
Luboš Náhlík ◽  
Lucie Šestáková ◽  
Pavel Hutař
Keyword(s):  
Crack Propagation ◽  
Propagation Direction ◽  
External Loading ◽  
Small Scale ◽  
Material Interface ◽  
Linear Elastic ◽  
Crack Propagation Direction ◽  
Density Factor ◽  
Scale Yielding ◽  
Elastic Fracture

The paper deals with crack propagation in ceramic laminates. Assumptions of linear elastic fracture mechanics and small scale yielding are considered. Crack behaviour in a ceramic laminate body under external loading is investigated. Strong residual stresses due to different coefficients of thermal expansion of individual material layers are taken into account in finite element calculations. The change of crack propagation direction at the material interface is estimated on the base of the strain energy density factor and maximum tangential stress criteria. The influence of thickness of laminate layers on crack propagation direction is estimated. The stepwise crack propagation through the Al2O3-ZrO2 ceramic laminate is numerically estimated. It can be concluded that good agreement between the estimated crack path and experimental data was found.

Numerical Investigation of Stress Singularities in Cracked Bimaterial Body

2008 ◽  
Vol 385-387 ◽  
pp. 125-128 ◽  
Author(s):  
Luboš Náhlík ◽  
Lucie Šestáková ◽  
Pavel Hutař
Keyword(s):  
Stress Singularity ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Material Interface ◽  
Element Analysis ◽  
Linear Elastic ◽  
Singularity Exponents ◽  
Singularity Exponent ◽  
Scale Yielding ◽  
Elastic Fracture

Composite materials or generally materials with interfaces are nowadays used in many varied engineering applications. In comparison with classical engineering materials the existence of material interface causes locally different stress distribution, which can strongly influence behaviour of whole structure and can have an important influence on failure mechanisms of such materials. The paper presented is devoted to the investigation of stress singularity exponents of a crack growing in a bimaterial body perpendicularly to the interface and touching the material interface. Discrepancies between value of stress singularity exponent in the centre of bimaterial body and on the free surface were found. The assumptions of linear elastic fracture mechanics (LEFM) and small scale yielding (SSY) are considered. For numerical calculations finite element analysis was used. Results obtained can contribute to a better understanding of failure of materials with interfaces.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

Investigation on Stress and Strain Singularity in LEFM

2006 ◽  
Vol 306-308 ◽  
pp. 31-36
Author(s):  
Zheng Yang ◽  
Wanlin Guo ◽  
Quan Liang Liu
Keyword(s):  
High Stress ◽  
Crack Tip ◽  
Plane Stress State ◽  
Stress And Strain ◽  
Linear Elastic ◽  
Geometrical Nonlinear ◽  
Maximum Crack ◽  
Elastic Fracture ◽  
Plain Strain ◽  
Strain Singularity

Stress and strain singularity at crack-tip is the characteristic of Linear Elastic Fracture Mechanics (LEFM). However, the stress, strain and strain energy at crack-tip may be infinite promoting conflicts with linear elastic hypothesis. It is indicated that the geometrical nonlinear near the crack-tip should not be neglected for linear elastic materials. In fact, the crack-tip blunts under high stress and strain, and the singularity vanishes due to the deformation of crack surface when loading. The stress at crack-tip may still be very high even though the singularity vanishes. The low bound of maximum crack-tip stress is the modulus of elastic in plane stress state, while in plain strain state, it is greater than the modulus of elastic, and will increase with the Poisson’s ratio.

Fabrication of SiC Particulates Reinforced MoSi2 Composite Coating by Laser Cladding

2008 ◽  
Vol 373-374 ◽  
pp. 304-307
Author(s):  
Sen Yang ◽  
Ming Run Wang ◽  
Tao Gong ◽  
Wen Jin Liu
Keyword(s):  
Wear Resistance ◽  
Laser Cladding ◽  
Continuous Wave ◽  
Steel Substrate ◽  
Laser Output Power ◽  
Scanning Velocity ◽  
Sic Particulates ◽  
Metallurgical Bond ◽  
Improve Wear Resistance

In order to improve wear resistance of carbon steel, laser cladding experiments were carried out using a 3kW continuous wave CO2 laser. The diameter of the laser beam was 3-5mm, the scanning velocity was 3-10mm/s, and the laser output power was 1.0-1.3kW. The experimental results showed that MoSi2/SiCP composites coating could be in-situ synthesized from mixture powders of molybdenum, silicon and SiC by laser cladding. A good metallurgical bond between the coating and the substrate could be achieved. The microstructures of the coating were mainly composed of MoSi2, SiC and FeSiMo phases. The average microhardness of the coating was about HV0.21300, about 6.0 times larger than that of steel substrate.

Ni Content Surface Layer Produced by Laser Surface Treatment on Amorphisable Cu Base Alloy

2010 ◽  
Vol 649 ◽  
pp. 101-106
Author(s):  
Mária Svéda ◽  
Dóra Janovszky ◽  
Kinga Tomolya ◽  
Jenő Sólyom ◽  
Zoltán Kálazi ◽  
...  
Keyword(s):  
Surface Layer ◽  
Surface Treatment ◽  
Laser Cladding ◽  
Base Alloy ◽  
Laser Surface ◽  
Laser Alloying ◽  
Laser Surface Treatment ◽  
Ni Content ◽  
Wide Range ◽  
The Matrix

The aim of our research was to comparatively examine Ni content surface layers on amorphisable Cu base alloy produced by different laser surface treatments. Laser surface treatment (LST) techniques, such as laser surface melting, laser alloying and laser cladding, provide a wide range of interesting solutions for the production of wear and corrosion resistant surfaces. [1,2] With LST techniques, the surface can be: i) coated with a layer of another material by laser cladding, ii) the composition of the matrix can be modified by laser alloying. [3] Two kinds of laser surface treatment technologies were used. In the case of coating-melting technology a Ni content surface layer was first developed by galvanization, and then the Ni content layer was melted together with the matrix. In the case of powder blowing technology Ni3Al powder was blown into the layer melted by laser beam and Argon gas. LST was performed using an impulse mode Nd:YAG laser. The laser power and the interaction time were 2 kW and 20÷60 ms. The characterization of the surface layer microstructure was performed by XRD, scanning electron microscopy and microhardness measurements.

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