FINITE ELEMENT SIMULATION OF ND:YAG LASER SHOCKPEENED NICKEL
CHROME, COBALT CHROME BASE METAL ALLOY FOR DENTAL APPLICATION
ILAVARASAN S 2010118017
KARTHIKEYAN S 2010118024
KUMAR K 2010118026
SARATH RAJA G 2010118040Project Guide Dr. K Shanmuga Sundaram
Associate ProfessorDepartment of Mechanical Engineering
College of Engineering, GuindyAnna University, Chennai-25
IntroductionThe main objective of this project is to give a solution to the
material selection for the dental implants or any other dental treatments.
Dental Implants are become necessary now a days. Because,
• 69% of adults at an age of 35 to 44, lost at least one of their permanent teeth by accident, gum disease or failed root canal.• 26% of adults at an age of 74, have lost all their permanent teeth.
Objective Selecting the suitable material,
laser for the dental application and comparing the changes in the mechanical properties after doing shock peening operation
Hardness Wear resistance Yield strength Ultimate strength Modulus of Elasticity
The experimental results and the theoretical results (simulation) are compared and studied
Material SelectionSelection of Materials are based on the following things,
• Bio compatibility• Color• Life • Durability• Easy for shaping• Aesthetics• Physical properties
• Low thermal conductivity and expansion• Resistance to wear and abrasion• Resistance to chemical erosion
• Flexibility to adopt to a shape• Strength to withstand the Mastication force
Material Selection Disadvantages • Poor Strength• High cost• Low Wear resistance• Less aesthetics• Takes longer time to make• Difficult to adjust• Dull in tooth color• May irritate the sensitive teeth (conducts cold)• High cost• Galvanic Shock• More brittle• Less life• Chance for future cavities• More time to place
o Gold Alloyo Porcelaino Plastic + Fine
Glasso Titaniumo Cobalt
Chromiumo Nickel Chrome
Suitable MaterialsCHEMICAL COMPOSITION :: Ni-Cr CHEMICAL COMPOSITION :: Co-Cr
ELEMENT PROPOSITION
NICKEL 65.2 %
CHROME 22.5 %
MOLYBDENUM 9.5 %
OTHERS (Fe, Si, Mn, Nb)
2.8 %
ELEMENT PROPOSITION
COBALT 61 %
CHROMIUM 26 %
MOLYBDENUM 6 %
TUNGSTEN 5 %
OTHERS (Si, Fe, Ce) 2 %
Laser Shock Peening Innovative surface enhancement process for
increasing resistance of the components. This process creates compressive stress, four to
five times deeper than conventional shot peening process.
This compressive surface stresses inhibit the initiation and propagation of fatigue cracks.
The peening drives a high amplitude shock wave into a material surface using high energy pulsed laser.
Hence the purpose of this study is to compare mechanical properties with microstructure of Nd-YAG laser treated and non-treated on Ni-Cr and Co-Cr
Nd: YAG Laser Shock peening• 0.4 mm to 1 mm• Low cost and easily available• produce continuous laser at
room temperature• portable systems
Parameter
ConstantSpot Diameter 1.2 mmPulse Duration 10 msDepth of Penetration 0.48 to 0.73 mmArgon Shielding 450
Peening Speed 160 mm/sNo of Scan per Second 4
Variables Pulse Energy Density 450 , 340 , 430 J/cm2
Pulse Frequency 1.1, 0.5, 2.5 kHz
Tensile Specimen using Pro/E
Finite Element Analysis Structural – Static Analysis Solid 185 Element Size 0.0001 (Fine
Mesh)
Meshed view of Specimen
Displacement Vector Sum X Component Displacement
Y Component Displacement Z Component Displacement
1st Principal Stress Von Mises Stress
XY Shear Stress Z Component Stress
1st principal Strain Von Mises Strain
Z Component Strain Elastic Strain Intensity
Improved Mechanical Properties
Vector Plot of Displacement
Vector Plot of Elastic Strain
ResultThe Strain value of the Co-Cr Alloy got the smallest value than
the Ni-Cr Alloy. So the less strain value material is opted for Dental applications.Obviously Co-Cr alloy is better than Ni-Cr alloy.
Maximum Strain Value of Ni-Cr alloy : 657 Maximum Strain Value of Co-Cr alloy : 553
ResultSince the Co-Cr alloy is suitable for dental applications, the
Laser Parameter can be identified.
Pulse Energy Density value at max. strain value is 360×104J/m2
Pulse Energy Density value at min. strain value is 420×104 J/m2
So the least strain value is occurred during the Pulse Energy Density value of 420 ×104 J/m2
ConclusionLaser Shock Peening process is a trendsetter now a days in the
medical field. It’s low cost and accurate operations make it popular. So that it gives an exact solution for all kind of age group who are all came with a dental problem.
Nickel Chromium and Cobalt Chromium are some important materials in dental implants. These materials can be used in dental applications without doing shock peening process. But it cannot withstand for a longer period. LSP improves the fatigue strength and compressive stress of the material.
The aesthetics of Co-Cr is little lower than Ni-Cr. Otherwise Co-Cr is the strongest material and can be shaped into any molar shape.
REFERENCES[1]O Brian WJ. 2002 Dental Materials and their selection. Chicago IL. Quintessence Publishing Co., Inc.; 2002.p.372-377
[2]Ding K, Ye L. Laser Shock peening performance and process simulation. Cambridge: Woodhead Publishing; 2006
[3]Ballard P. Residual Stresses induced by rapid impact – Application for laser shocking. Ecolo Polytechnique, April 1991
[4]Philips and Anusavic. Science of Dental Materials
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