Young's Modulus Interpreted from Compression Tests with End Friction

1997 ◽  
Vol 123 (1) ◽  
pp. 1-7 ◽  
Author(s):  
K. T. Chau
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Compression Tests

Fabrication and Testing of Planar Stent Mesh Designs Using Carbon-Infiltrated Carbon Nanotubes

2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Kristopher Jones ◽  
Brian D. Jensen ◽  
Anton Bowden
Keyword(s):  
Carbon Nanotubes ◽  
Young’S Modulus ◽  
Fracture Strain ◽  
Young's Modulus ◽  
Chemical Vapor ◽  
Pyrolytic Carbon ◽  
Compression Tests ◽  
Element Analysis ◽  
Percent Elongation ◽  
Fea Model

This paper explores and demonstrates the potential of using pyrolytic carbon as a material for coronary stents. Stents are commonly fabricated from metal, which has worse biocompatibilty than many polymers and ceramics. Pyrolytic carbon, a ceramic, is currently used in medical implant devices due to its preferable biocompatibility properties. Micropatterned pyrolytic carbon implants can be created by growing carbon nanotubes (CNTs), and then filling the space between with amorphous carbon via chemical vapor deposition (CVD). We prepared multiple samples of two different stent-like flexible mesh designs and smaller cubic structures out of carbon-infiltrated carbon nanotubes (CI-CNT). Tension loads were applied to expand the mesh samples and we recorded the forces at brittle failure. The cubic structures were used for separate compression tests. These data were then used in conjunction with a nonlinear finite element analysis (FEA) model of the stent geometry to determine Young's modulus and maximum fracture strain in tension and compression for each sample. Additionally, images were recorded of the mesh samples before, during, and at failure. These images were used to measure an overall percent elongation for each sample. The highest fracture strain observed was 1.4% and Young's modulus values confirmed that the material was similar to that used in previous carbon-infiltrated carbon nanotube work. The average percent elongation was 86% with a maximum of 145%. This exceeds a typical target of 66%. The material properties found from compression testing show less stiffness than the mesh samples; however, specimen evaluation reveals poorly infiltrated samples.

The Influence of the Bauschinger Effect on the Yield Stress, Young’s Modulus, and Poisson’s Ratio of a Gun Barrel Steel

2005 ◽  
Vol 128 (2) ◽  
pp. 179-184 ◽  
Author(s):  
J. Perry ◽  
M. Perl ◽  
R. Shneck ◽  
S. Haroush
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Bauschinger Effect ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Residual Stress Field ◽  
Gun Barrel

The Bauschinger effect (BE) was originally defined as the phenomenon whereby plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor (BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the BE. The aim of the present work is to quantitatively evaluate the influence of plastic deformation on other material properties such as Young’s modulus and Poisson’s ratio for gun barrel steel, thus extending the definition of the Bauschinger effect. In order to investigate the change in this material’s properties resulting from plastic deformation, several uniaxial tension and compression tests were performed. The yield stress and Young’s modulus were found to be strongly affected by plastic strain, while Poisson’s ratio was not affected at all. An additional result of these tests is an exact zero offset yield point definition enabling a simple evaluation of the BEF. A simple, triphase test sufficient to characterize the entire elastoplastic behavior is suggested. The obtained experimental information is readily useful for autofrettage residual stress field calculations.

Influence of Experimental Protocols on the Mechanical Properties of the Intervertebral Disc in Unconfined Compression

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Maximilien Recuerda ◽  
Simon-Pierre Coté ◽  
Isabelle Villemure ◽  
Delphine Périé
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Nucleus Pulposus ◽  
Annulus Fibrosus ◽  
Young's Modulus ◽  
Viscoelastic Model ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Experimental Conditions ◽  
Experimental Protocols

The lack of standardization in experimental protocols for unconfined compression tests of intervertebral discs (IVD) tissues is a major issue in the quantification of their mechanical properties. Our hypothesis is that the experimental protocols influence the mechanical properties of both annulus fibrosus and nucleus pulposus. IVD extracted from bovine tails were tested in unconfined compression stress-relaxation experiments according to six different protocols, where for each protocol, the initial swelling of the samples and the applied preload were different. The Young’s modulus was calculated from a viscoelastic model, and the permeability from a linear biphasic poroviscoelastic model. Important differences were observed in the prediction of the mechanical properties of the IVD according to the initial experimental conditions, in agreement with our hypothesis. The protocol including an initial swelling, a 5% strain preload, and a 5% strain ramp is the most relevant protocol to test the annulus fibrosus in unconfined compression, and provides a permeability of 5.0 ± 4.2e−14m4/N·s and a Young’s modulus of 7.6 ± 4.7 kPa. The protocol with semi confined swelling and a 5% strain ramp is the most relevant protocol for the nucleus pulposus and provides a permeability of 10.7 ± 3.1 e−14m4/N·s and a Young’s modulus of 6.0 ± 2.5 kPa.

scholarly journals Influence of Degradation Products on the Elastic Stiffness Properties of Porous Absorbable Scaffolds Made From Bioabsorbable Metals

2021 ◽  
Author(s):  
Jannik Bühring ◽  
Maximilian Voshage ◽  
Johannes Heinrich Schleifenbaum ◽  
Holger Jahr ◽  
Kai-Uwe Schröder
Keyword(s):  
Finite Element ◽  
Young’S Modulus ◽  
Degradation Products ◽  
Young's Modulus ◽  
Element Model ◽  
Elastic Stiffness ◽  
Porous Scaffolds ◽  
Compression Tests ◽  
Substrate Layer ◽  
Stiffness Properties

For orthopaedic applications, additive manufactured (AM) porous scaffolds made of absorbable metals like magnesium, zinc or iron are of particular interest. They do not only offer the potential to design and fabricate bio-mimetic or rather bone equivalent mechanical properties, they also do not need to be removed in further surgery. Located in a physiological environment, scaffolds made of absorbable metals show a decreasing Young’s modulus over time, due to product dissolution. For WE43 scaffolds, during the first days an increase of the smeared Young's modulus can be observed, which is mainly attributed to a forming substrate layer of degradation products on the struts surfaces. In this study the influence of degradation products on the stiffness properties of metallic scaffolds is investigated. For this, analytical calculations and finite element simulations are performed to study the influence of the substrate layer thickness and Young's modulus for single struts and for a new scaffold geometry with adapted polar f2cc,z unit cells. The finite element model is further validated by compression tests on AM scaffolds made from Zn1Mg. The results show, that even low thicknesses and Young's moduli of the substrate layer increases significantly the smeared Young's modulus under axial compression.

scholarly journals Influence of Degradation Product Thickness on the Elastic Stiffness of Porous Absorbable Scaffolds Made from an Bioabsorbable Zn–Mg Alloy

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6027
Author(s):  
Jannik Bühring ◽  
Maximilian Voshage ◽  
Johannes Henrich Schleifenbaum ◽  
Holger Jahr ◽  
Kai-Uwe Schröder
Keyword(s):  
Finite Element ◽  
Young’S Modulus ◽  
Degradation Products ◽  
Young's Modulus ◽  
Element Model ◽  
Elastic Stiffness ◽  
Porous Scaffolds ◽  
Compression Tests ◽  
Young’S Moduli ◽  
Substrate Layer

For orthopaedic applications, additive manufactured (AM) porous scaffolds made of absorbable metals such as magnesium, zinc or iron are of particular interest. They do not only offer the potential to design and fabricate bio-mimetic or rather bone-equivalent mechanical properties, they also do not need to be removed in further surgery. Located in a physiological environment, scaffolds made of absorbable metals show a decreasing Young’s modulus over time, due to product dissolution. For magnesium-based scaffolds during the first days an increase of the smeared Young’s modulus can be observed, which is mainly attributed to a forming substrate layer of degradation products on the strut surfaces. In this study, the influence of degradation products on the stiffness properties of metallic scaffolds is investigated. For this, analytical calculations and finite-element simulations are performed to study the influence of the substrate layer thickness and Young’s modulus for single struts and for a new scaffold geometry with adapted polar cubic face-centered unit cells with vertical struts (f2cc,z). The finite-element model is further validated by compression tests on AM scaffolds made from Zn1Mg (1 wt% Mg). The results show that even low thicknesses and Young’s moduli of the substrate layer significantly increases the smeared Young’s modulus under axial compression.

Mechanical Considerations of Shin-Etsu Elastomer As a Z-Axis Interconnect

2001 ◽  
Author(s):  
C. Cox ◽  
W. F. Schmidt ◽  
M. H. Gordon ◽  
W. Marsh ◽  
G. Bates ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Research Effort ◽  
Electrical Contact ◽  
Surface Boundary ◽  
Compression Tests ◽  
Board Test ◽  
Frictional Forces ◽  
Surface Boundary Condition ◽  
Interconnect Technology

Abstract This research effort addresses the integration of a dense z-axis interconnect technology, Shin-Etsu, into a 3D thermo-mechanical multi-chip module with two to eight stack layers. Shin-Etsu is a matrix of vertical beryllium-copper wires embedded in silicone. Since it is a composite material, accurately determining Shin-Etsu’s mechanical properties is extremely important for estimating long-term reliability of the electronic package. Five percent compression of the Shin-Etsu elastomer was specified to maintain proper electrical contact between substrates. To determine the corresponding force, Tinius-Olsen compression tests up to 15% were conducted on both single and double layer samples of Shin-Etsu. In addition, these data were used to infer Shin-Etsu’s Young’s modulus. Both series of test were also conducted with and without alumina (A12O3) to simulate the contact surface boundary condition between Shin-Etsu and the LTCC substrate (2 pieces were used for the single Shin-Etsu case, and 3 pieces were used for the 2 layer Shin-Etsu case). All compression tests follow the same trends, though the sample to sample scatter is relatively large (+/−75%). Because Shin-Etsu’s Poisson’s ratio is near 0.5 (volume is conserved), the frictional forces between the contact surfaces is important. By carefully accounting for these frictional forces, we infer a Young’s modulus for Shin-Etsu of 3.25 MPa. Using this value with the appropriate contact model (we found that a simpler model with infinite friction is suitable in our case), we are able to successfully design a two-board test vehicle which incorporates Shin-Etsu.

scholarly journals Properties of PMMA Bone Cement Modified with Nano-hydroxyapatite and Acetone

2019 ◽  
Vol 2 (4) ◽  
pp. 489
Author(s):  
Amin Zaza ◽  
Mohamed Habib ◽  
Nabil Fatahalla
Keyword(s):  
Bone Cement ◽  
Young’S Modulus ◽  
High Performance ◽  
Young's Modulus ◽  
Nano Particles ◽  
Polymerization Temperature ◽  
Compression Tests ◽  
Residual Monomer ◽  
Pmma Bone Cement ◽  
Pmma Cement

Fracture in the adjacent levels is one of the consequences to the use of commercial poly methylmethacrylate (PMMA) bone cement. Modified PMMA with a reduced Young’s modulus was found to be safer for cancellous bone augmentation procedures. The aim of this research was to study the effect of adding hydroxyapatite (HA) nano-particles and acetone on different properties of PMMA cement. A commercial PMMA cement was used as a model for bone cement. Three groups of modified PMMA/nano-HA were investigated by adding 2, 4 and 6 wt. % of HA. Acetone as a porogen mixed with distilled water in different amounts (A/W: 1:1, 2:1.5 and 2:1g) was used to produce porous PMMA cement. The residual monomer, polymerization and mechanical properties under tension and compression tests were investigated. Young’s modulus detected from compression test decreased from 826.5±10 to 728±66 MPa by adding 6wt.% HA. Adding acetone to PMMA with 2:1.5g (A/W) has decreased the compressive Young’s modulus to 753±38 MPa. High Performance Liquid Chromatography (HPLC) measurements were carried out with intervals of 2 hours, 6 hours and 24 hours to evaluate the residual monomer for all groups. The amount of residual monomer has decreased after 24 hours of curing by adding acetone and nano-HA. Modifying PMMA by HA and acetone have inconsistent effect on the polymerization temperature. It was concluded that HA and acetone can be used to reduce the stiffness and residual monomer with enhanced biocompatibility of the commercial PMMA bone cement.

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