Coming Full Circle: The Application of Microtechnology Techniques to Evaluate Bulk Materials

2011 ◽  
Vol 1298 ◽  
Author(s):  
David Read ◽  
Nicholas Barbosa
Keyword(s):  
Test Procedure ◽  
Gage Section ◽  
Load Cell ◽  
Image Correlation ◽  
Bulk Materials ◽  
Full Circle ◽  
Specimen Material ◽  
Test Frame ◽  
Specimen Grip ◽  
Bow Tie

ABSTRACTA tensile test procedure that accommodates specimens with gage section 25 μm thick, 70 μm wide and 360 μm long was developed and demonstrated. The instrumentation and technique were adapted from those previously developed and used to test thin films, by increasing both the force capacity of the load cell and the stiffness of the pull rod. Specimens with bow-tie geometry were fabricated by photolithography from nominally 25 μm thick full hard stainless steel 302 foil. A silicon test frame fabricated by bulk micromachining techniques included tapered grips in the form of recesses in its top surface that accepted and retained the specimen grip sections. One grip was on the fixed outer portion of the frame. The other grip was on a plate suspended in the center of the frame by long slender silicon beams. Force was imposed on this plate by pin loading. The force was measured by use of a custom load cell. The displacement was measured by sub-pixel digital image correlation to surface features on the two ends of the gage section, applied to images with a resolution of approximately 0.8 μm per pixel. Yield and ultimate strengths and elongation values consistent with vendor-provided information were obtained. The values of Young’s modulus were scattered but within the range of expected behavior for the specimen material.

An Experimental Measurement of Toughness Locus for a Ductile Material

2005 ◽  
Vol 297-300 ◽  
pp. 2410-2415 ◽  
Author(s):  
Dong Hak Kim ◽  
Jeong Hyun Lee ◽  
Ho Dong Kim ◽  
Ki Ju Kang
Keyword(s):  
Crack Length ◽  
Nuclear Power ◽  
Power Plants ◽  
Test Procedure ◽  
Stress Triaxiality ◽  
Crack Tip ◽  
Potential Drop ◽  
Image Correlation ◽  
Ductile Material ◽  
Main Steam

A toughness locus Jc-Q for a ductile steel, SA106 Grade C used in the main steam piping of nuclear power plants, has been experimentally evaluated. Along with the standard fracture test procedure for J-R curve, Q as the second parameter governing stress triaxiality nearby the crack tip is measured from the displacements nearby the side necking which occurs near the crack tip on the lateral surface of a fracture specimen. The displacements nearby the side necking are measured from the digital images taken during the fracture experiment based on Stereoscopic Digital Photography (SDP) and high resolution Digital Image Correlation (DIC) software. The crack length is monitored by Direct Current Potential Drop (DCPD) method and the J-R curve is determined according to ASTM standard E1737-96. The effects of crack length, specimen geometry and thickness of specimen are studied, which are included in the toughness locus Jc-Q.

Multiple loading method for field testing drilled piers

1985 ◽  
Vol 22 (4) ◽  
pp. 592-599
Author(s):  
R. G. Horvath
Keyword(s):  
Test Procedure ◽  
Load Cell ◽  
Load Test ◽  
Test Method ◽  
Single Test ◽  
Loading Test ◽  
Shaft Resistance ◽  
Loading Method ◽  
Multiple Loading ◽  
Base Load

A multiple loading testing method is suggested, which permits testing a single drilled pier foundation under three different conditions of load support. The pier may be tested under conditions of combined shaft and end-bearing resistance, end-bearing resistance only, and shaft resistance only. The advantages of this multiple loading test method include observation of the load-transfer and displacement behaviours of the pier under these three different support conditions and verification of the values obtained for the components of load support, i.e., shaft and end-bearing resistance, all from a single test pier.A special base load cell capable of performing a different function during each cycle of loading is required. A suitable load cell, consisting of a series of Freyssi flatjacks, and the method of operation are described.A multiple loading test procedure was used successfully as part of a field investigation program on full-scale pier sockets in weak shale. Data on the load-displacement behaviour of the pier tested using the multiple loading method are reported. Information concerning piers tested using conventional single loading methods are provided for comparison.The multiple loading test results were in good agreement with results obtained from conventional testing methods. Thus the multiple loading test method provides an economical means of obtaining a large amount of design information for drilled pier foundation systems, using a single test pier. Key words: field load test, multiple loading, drilled piers and caissons, shaft resistance, end-bearing resistance, combined shaft and end-bearing resistances, base load cell, shale.

Influence of specimen size on the mechanical properties of microlattices obtained by selective laser melting

2019 ◽  
pp. 095440621986974
Author(s):  
Matteo Gavazzoni ◽  
Laura Boniotti ◽  
Stefano Foletti
Keyword(s):  
Elastic Modulus ◽  
Selective Laser Melting ◽  
Test Procedure ◽  
Specimen Size ◽  
The Body ◽  
Image Correlation ◽  
Good Prediction ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Laser Melting

A detailed study of compression tests on lattice structures obtained by selective laser melting with AlSi7Mg powder is presented here. Two different cell topologies have been investigated: the body-centered cubic cell and the face centered cubic cell or 3D Warren structure. Specimens of different volume have been printed in order to investigate the effect of the size on the mechanical response and properties of the structure. Particular attention has been paid to the definition of the test procedure and the analysis of the data to properly characterize the microlattice. No remarkable effect of the specimen size has been found in terms of elastic modulus and yielding stress. On the contrary, the maximum stress and the failure mechanism are influenced by the size of the specimen; for the body-centered cubic cell, a detailed analysis has been performed through digital image correlation of the failure. Test results have been compared with the results of an elasto-plastic simulation performed on a single cell of lattice with periodic boundary conditions, showing a good prediction in terms of elastic modulus and yielding stress.

Non-Destructive Evaluation of Composite Adhesive Kissing Bond

2013 ◽  
Author(s):  
Yingtao Liu ◽  
Joel Johnston ◽  
Aditi Chattopadhyay
Keyword(s):  
Structural Integrity ◽  
Adhesive Bond ◽  
Image Correlation ◽  
Bonded Joints ◽  
Hydraulic Test ◽  
Ultrasonic Methods ◽  
Non Destructive Evaluation ◽  
Test Frame ◽  
Adhesive Bonded Joints ◽  
Non Destructive

Adhesive bonded joints have been increasingly employed in aerospace, automotive, and other mechanical systems due to the advantages of uniform stress distribution, less stress concentration, light in weight, etc. However, the early damage stage of the adhesive bond joints, which are usually named as kissing bond, can significantly impact the structural integrity and safety. Kissing bond is difficult to detect and identify using current non-destructive evaluation (NDE) techniques since there is no clearly gap or interface between the bond area. Attempts using advanced ultrasonic methods have reached limited success, but more reliable methods need to be developed before adhesive joints can be more widely applied to the engineering field. This paper focuses on the development of detection method using digital image correlation (DIC) technique. Three types of adhesive kissing bond joint samples were fabricated using different contamination recipe to simulate the kissing bonds. The performance of the fabricated joint samples were tested using uniaxial hydraulic test frame and the detection capability of DIC system was investigated. The noncontact strain field measurement method using DIC can indicate the existence of kissing bonds with limited load. The results of DIC measurement is encouraging and can be further used for the NDE estimation of mechanical properties of the kissing bond.

scholarly journals Experimental Characterisation of Parameters Controlling the Compressive Failure of Pultruded Unidirectional Carbon Fibre Composites

2010 ◽  
Vol 24-25 ◽  
pp. 15-22 ◽  
Author(s):  
Ole Thybo Thomsen ◽  
K.K. Kratmann
Keyword(s):  
Compressive Strength ◽  
Carbon Fibre ◽  
Test Procedure ◽  
Kink Band ◽  
Image Correlation ◽  
Band Formation ◽  
Shear Properties ◽  
Axial Splitting ◽  
Strength Models ◽  
Carbon Fibre Composites

The classical kink-band formation models predict that the compressive strength of UD carbon fibre reinforced composite materials (UD CFRP) is governed by fibre misalignment as well as of the mechanical shear properties. A new image analysis procedure for experimental determination of the fibre misalignment, the Fourier transform misalignment analysis (FTMA), has been developed. Moreover, a modified asymmetric Iosipescu test specimen geometry has been developed and validated for accurate measurement of the composite material shear properties without parasitic effects due to axial splitting. In the test procedure the shear strain distribution is measured using Digital Image Correlation (DIC) and the results calibrated based on FEA modelling results. Using the measured properties as input, the predictions of the classic compressive strength models have been compared with measured compressive strengths. Finally, an alternative approach to the classical kink band equilibrium has been proposed and demonstrated to provide more accurate predictions than the classical models.

Effect of Strain Rate on the Mechanical Behavior of 10-micron Long Polymeric Nanofibers

2006 ◽  
Vol 948 ◽  
Author(s):  
Mohammad Naraghi ◽  
Ioannis Chasiotis ◽  
Yuris Dzenis ◽  
Y. Wen ◽  
Hal Kahn
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Load Cell ◽  
Image Correlation ◽  
Leaf Spring ◽  
Polymeric Nanofibers ◽  
Novel Method ◽  
Microscopy Images ◽  
Rate Of Loading

ABSTRACTThe strain rate mechanical behavior of 12-micron long polymeric nanofibers was investigated. Experiments were carried out by a novel method that employs a MEMS-based leaf spring load cell attached to a polymeric nanofiber that is drawn with an external PZT actuator. The elongation of the fiber and the deflection of the load cell were calculated from optical microscopy images by using Digital Image Correlation (DIC) and with 65 nm resolution in fiber extension. The nanofibers were fabricated from electrospun polyacrylonitrile (PAN) with MW = 150,000 and diameters between 300-600 nm. At strain rates between 0.00025 s−1 to 0.025 s−1 the fiber ductility scaled directly with the rate of loading while the tensile strength was found to vary non-monotonically: At 0.00025 s−1 material relaxations allowed for near-uniform fiber drawing with up to 120% ductility and 120 MPa maximum tensile strength. At the two faster rates the tensile strength scaled with the rate of loading but the fiber ductility was the result of a cascade of localized deformations at nanoscale necks with relatively constant wavelength for all fiber diameters.

scholarly journals Compression of structural foam materials – Experimental and numerical assessment of test procedure and specimen size effects

2017 ◽  
Vol 21 (1) ◽  
pp. 260-288 ◽  
Author(s):  
Moeen S Rajput ◽  
Magnus Burman ◽  
Joonas Köll ◽  
Stefan Hallström
Keyword(s):  
Standardized Test ◽  
Test Procedure ◽  
Finite Size ◽  
Test Methods ◽  
Specimen Size ◽  
Image Correlation ◽  
Structural Foam ◽  
Various Boundary Conditions ◽  
Closed Cell ◽  
Out Of Plane

This study was initiated based on the observation that standardized test methods for flatwise compression of foam materials, give significantly different test results for the measured moduli, and that these standards to date lack adequate instructions on how the strain should be measured and what specimen size should be used. A brief review of previous work shows that existing test methodologies provide significantly different results for the compressive moduli of foams depending on how the strains are measured. A thorough experimental study of the out-of-plane compressive properties is conducted on three different closed-cell foam materials, where strains measured with two different extensometer placements, and with digital image correlation, come out significantly differently. A parametric study is also performed showing that the results vary considerably with in-plane specimen dimensions, indicating effects of finite size and localized strain at edges. Both stochastic amorphous and homogenized finite element models of foam back the experimental observations by illustrating the effects of finite size and various boundary conditions on the measured properties.

scholarly journals Development of comparative investigation method for timing chain wear analysis using oscillating tribometer

2021 ◽  
Author(s):  
László Paulovics ◽  
Rajmund Kuti ◽  
Jan Rohde-Brandenburger ◽  
Csaba Tóth-Nagy
Keyword(s):  
Friction And Wear ◽  
Test Procedure ◽  
Cost Effective ◽  
Comparative Investigation ◽  
Test Method ◽  
Wear Analysis ◽  
Tribological System ◽  
Specimen Material ◽  
Complicated Surface ◽  
Ball On Disc

This paper presents the development of a test procedure to investigate timing chain components under abrasive stress on a tribometer. Engine developers use cost and time expensive engine dynamometer tests to investigate timing chain life expectancy under different conditions. Tribometer tests are fast and cost effective, but these use standardized specimen material and geometry that greatly differ from the original tribological system of the timing chain. Manufacturing specimens from the original chain material using the original technology is complicated; surface quality and hardness properties cannot be guaranteed. The aim of research was to develop a test method for rapid and cost-effective comparison of engine lubricants, timing chain materials or coatings, as well as to assess the wear resistance of the chain to contaminants.  Various uncontaminated and carbon black blended lubricants were compared using standard-based ball-on-disc tribometer tests to tribometer tests using actual timing chain components (bush-on-pin test) of a Diesel engine. Lubricants were ranked in terms of coefficient of friction and wear. Results showed that bush-on-pin tests were comparably suitable for testing lubricants when evaluated against standard ball-on-disc tribometer tests.

Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

1978 ◽  
Vol 36 (3) ◽  
pp. 70-77 ◽  
Author(s):  
R.M. Glaeser ◽  
S.B. Hayward
Keyword(s):  
Diffraction Pattern ◽  
Structural Information ◽  
Structural Disorder ◽  
Structural Features ◽  
Biological Macromolecules ◽  
Diffraction Intensity ◽  
Object Structure ◽  
Specimen Material ◽  
Unit Cells ◽  
Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

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