NFT Wing Protection on HAMR Head Using a Window Underlayer Structure

2017 ◽  
Author(s):  
Robert Smith ◽  
Sukumar Rajauria ◽  
Sripathi Vangipuram Canchi ◽  
Qing Dai
Keyword(s):  
Thermal Expansion ◽  
Material Properties ◽  
Direct Contact ◽  
Mechanical Reliability ◽  
Standard Material ◽  
Structure Simulation ◽  
Recording Conditions ◽  
Small Thermal Expansion

Ensuring the mechanical reliability of the NFT is critical due to contact with the disk during touchdown and the presence of high thermal asperities (TAs) at low clearance. Here, we tune the thermomechanical design of the HAMR head to ensure the NFT is protected from direct contact with the disk. We propose embedding the NFT in a localized window of underlayer material chosen for its small thermal expansion in comparison to a standard material such as alumina. By optimizing the size and material properties of the window structure, simulation predicts that the NFT is well protected under recording conditions.

Size- and temperature-dependent Young's modulus and size-dependent thermal expansion coefficient of thin films

2016 ◽  
Vol 18 (31) ◽  
pp. 21508-21517 ◽  
Author(s):  
Xiao-Ye Zhou ◽  
Bao-Ling Huang ◽  
Tong-Yi Zhang
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Material Properties ◽  
Essential Role ◽  
Young's Modulus ◽  
Temperature Dependent ◽  
Size Dependent

Surfaces of nanomaterials play an essential role in size-dependent material properties.

Influence of Leaning Materials on the Quality of Building Ceramics

2021 ◽  
Vol 903 ◽  
pp. 197-202
Author(s):  
Ruta Švinka ◽  
Visvaldis Švinka ◽  
Maris Rundans ◽  
Inta Timma ◽  
Laila Petersone
Keyword(s):  
Thermal Expansion ◽  
Glass Fibre ◽  
Material Properties ◽  
Quartz Sand ◽  
Main Method ◽  
Different Types ◽  
Ceramic Building ◽  
Formation Of Cracks

Clay of the deposit Liepa is used for the production of ceramic building and finishing bricks in the factory “Lode” in Latvia. In the present work different types of these clays were investigated and “quartz effect” was determined using quartz sand as a leaning material. The substitution of quartz sand with milled E-glass fibre from Valmiera Glass was investigated and the changes in the magnitude of the quartz inversion effect were analysed. Thermal expansion was the main method for the determination of possible formation of cracks during technological process. Powder of milled glass fibre in amount of 5–10 % affects such properties as water uptake, porosity and apparent density and provides the required material properties at a lower firing temperature.

scholarly journals The Use of Recycled Carpet in Low-Cost Composite Tooling Materials

Recycling ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 12 ◽  
Author(s):  
Kunal Mishra ◽  
Sarat Das ◽  
Ranji Vaidyanathan
Keyword(s):  
Mechanical Properties ◽  
Thermal Expansion ◽  
Material Properties ◽  
Coefficient Of Thermal Expansion ◽  
Low Cost ◽  
Value Engineering ◽  
Compressive Properties ◽  
Structural Composites ◽  
Environmental Deterioration ◽  
Composite Tooling

More than 250,000 metric tons (600 million pounds) of carpet are dumped in landfills every year. That creates a significant concern regarding environmental deterioration and economic liability. It is therefore imperative to develop sustainable post-consumer carpet-based products for high-value engineering applications such as composite tooling. To be considered as an acceptable composite tooling material, the composite needs to meet certain required properties such as a low coefficient of thermal expansion, excellent compressive properties, and high a hardness value after repeated exposure to curing cycles. The tooling composites must also exhibit the ability to endure several curing cycles, without deteriorating the mechanical properties. In the present investigation, post-consumer carpet has been recycled in the form of structural composites for tooling applications. The recycled carpet composites have been reinforced with 0.5 wt.% of graphene nanoplatelets to modify the material properties of the carpet composites. The results from compressive and hardness experiments demonstrate that the recycled carpet preserved its mechanical integrity even after several curing cycles. This indicates that recycled carpet composites have the potential to be a low-cost composite tooling alternative for the industry.

Viscoelastic Material Properties of SU-8 and Carbon-Nanotube-Reinforced SU-8 Materials

2006 ◽  
Author(s):  
Seungbae Park ◽  
Soonwan Chung ◽  
Harold Ackler ◽  
Sandeep Makhar
Keyword(s):  
Carbon Nanotube ◽  
Strain Rate ◽  
Viscoelastic Material ◽  
Material Properties ◽  
Elevated Temperatures ◽  
Mechanical Reliability ◽  
Creep Stress ◽  
Post Exposure Bake ◽  
Carbon Nano Tube ◽  
Composite Carbon

The viscoelastic material properties of SU-8 and carbon nanotube-reinforced SU-8 composite material are characterized by tensile testing. Dogbone samples of 0.1mm thickness are prepared by micro-fabrication process, which is composed of spin coat, soft bake, expose, and post exposure bake. To fabricate CNT polymer composite, carbon nano-tube of 0.2wt% is mixed with SU-8. To observe the effect of applied strain rate and temperature on Young's modulus and Poisson's ratio, strain rate is varied from 5×10-5 to 2.5×10-4 (/sec) at elevated temperatures in the range of 25 to 200°C. Since the viscoelastic material properties are important in polymer, creep, stress relaxation and dynamic mechanical analyses are performed at elevated temperatures. The viscoelastic material properties of SU-8 and CNT-reinforced SU-8 composite are compared, and the mechanical reliability of these polymers in MEMS applications is discussed.

Analytical Solution of Thermal Stresses in a Functionally Graded Solid Cylinder within Parabolic Continuous Grading

2013 ◽  
Vol 307 ◽  
pp. 364-367 ◽  
Author(s):  
Ali Ozturk ◽  
Müfit Gülgeç
Keyword(s):  
Thermal Expansion ◽  
Analytical Solution ◽  
Material Properties ◽  
Thermal Conduction ◽  
Thermal Stresses ◽  
Elasticity Modulus ◽  
Functionally Graded ◽  
Solid Cylinder ◽  
Graded Materials ◽  
Parabolic Form

This paper presents analytical solutions of the thermal stresses in a functionally graded solid cylinder with fixed ends in elastic region. These thermal stresses are due to the uniform heat generation inside the cylinder. Material properties of the functionally graded (FG) cylinder vary radially according to a parabolic form. The material properties are assumed to be independent of the temperature which are yield strength, elasticity modulus, thermal conduction coefficient, thermal expansion coefficient and Poisson’s ratio. The solutions for the thermal stresses are valid for both homogeneous and functionally graded materials.

A General Solution for the Elastoplastic Thermal Stresses in a Strain-Hardening Plate With Arbitrary Material Properties

1962 ◽  
Vol 29 (1) ◽  
pp. 151-158 ◽  
Author(s):  
A. Mendelson ◽  
S. W. Spero
Keyword(s):  
Thermal Expansion ◽  
General Solution ◽  
Strain Hardening ◽  
Material Properties ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Stress And Strain ◽  
Linear Strain ◽  
Hardening Material ◽  
General Method

A general method is presented for obtaining the elastoplastic stress and strain distributions in a thermally stressed plate of a strain-hardening material with temperature-varying modulus, yield point, and coefficient of thermal expansion. It is shown that for linear strain-hardening the solution can often be obtained in closed form. It is indicated that the error due to neglecting strain-hardening may sometimes be appreciable. The assumption that the total strain remains the same as that computed elastically (strain invariance) often leads to smaller errors than the neglect of strain-hardening.

Thermal Strain Measurements of Solder Joints in Second Level Interconnections Using Moire Interferometry

1992 ◽  
Vol 114 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Yifan Guo ◽  
Charles G. Woychik
Keyword(s):  
Thermal Expansion ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Low Cycle Fatigue ◽  
Thermal Strain ◽  
Moiré Interferometry ◽  
Moire Interferometry ◽  
Mechanical Reliability ◽  
Surface Mount ◽  
Inherent Strength

Low cycle fatigue of solder joints is one of the major kinds of failures in second level interconnections of an electronic package. The fatigue failure is caused by thermal strains which are created from a mismatch of coefficients of thermal expansion (CTE) that occurs between two levels of packaging. As the package approaches smaller dimensions, measurements of thermal strains in the solder interconnections become very difficult. In this paper, moire interferometry technique was applied to evaluate the thermal strains in the second level interconnections for both conventional pin-in-hole (PIH) packages and surface mount components. The coefficient of thermal expansion of each component was measured. Thermal strain distributions in the solder interconnections were determined, and reliability issues were discussed. The strains in solder joints of the PIH components were much higher than those of the stacked surface mount components. Even though the surface mount components had a lower inherent strength, their overall mechanical reliability was much higher since they had practically no localized strain concentrations.

Parametric study on the influence of material properties and geometry on the thermally induced bistability of composite laminates

2021 ◽  
pp. 095440622110456
Author(s):  
Samir A Emam ◽  
Tarun Pherwani ◽  
Aravindh Anil ◽  
Aeman Muhammed
Keyword(s):  
Thermal Expansion ◽  
Aspect Ratio ◽  
Material Properties ◽  
Parametric Study ◽  
Composite Laminates ◽  
Thickness Ratio ◽  
Thermally Induced ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Moduli Of Elasticity

This paper presents a parametric study on the key parameters that control the thermally induced bistability of cross-ply laminates. The influence of the material properties including the moduli of elasticity and the thermal expansion coefficients and the laminate’s geometry including the aspect ratio (AR) and the width-to-thickness ratio are investigated. The unsymmetric [Formula: see text] and the antisymmetric [Formula: see text] cross-ply laminates are investigated. Five key parameters are varied: the number of plies, the width-to-thickness ratio, the laminate’s aspect ratio, the ratio of the moduli of elasticity, and the ratio of the thermal expansion coefficients of the lamina. The laminate is assumed flat at the cured temperature and a uniform temperature gradient is applied until it is reduced to the room temperature. For each set of parameters, the stable equilibrium shapes of the laminate are obtained using a Ritz model. The ABAQUS finite element package is used to validate the model and an excellent agreement is obtained. Results that show the variation of the curvatures with the width-to-thickness ratio and the onset of the bistability for a variety of parameters are presented. The ratio of the moduli of elasticity and the thermal expansion coefficients significantly affect the critical width-to-thickness ratio at which the laminates become bistable. The unsymmetric laminates show bistability at a lower width-to-thickness ratio compared with the antisymmetric laminates. The results also show that the higher the aspect ratio, the lower the critical width-to-thickness ratio for stability for both laminates.

Sign in / Sign up

Export Citation Format

Share Document