Tailoring of Mechanical Properties in Microlaminates

1993 ◽  
Vol 308 ◽  
Author(s):  
M. Vill ◽  
D. P. Adams ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Tensile Testing ◽  
Testing Machine ◽  
Thick Layer ◽  
Thin Layers ◽  
Uniaxial Tensile ◽  
Strong Phase ◽  
Uniaxial Tensile Testing ◽  
And Tungsten

ABSTRACTA multiscalar approach is used to demonstrate the ability to control strength and toughness in microlaminates composed of molybdenum and tungsten. Here, two different thickness scales are utilized; an alternating stack of molybdenum and tungsten layers having thicknesses on the nanometer scale are combined with a layer of molybdenum having a thickness on the micron scale. The stack of thin layers acts as a strong phase and the thick layer acts as a tough phase. Multilayers of two configurations were fabricated which had total thicknesses of 31μm and 50μm. The tough phase thickness was 5μm for the 31μm multilayer and 1μm for the other. The strong phase contained a stack of 29 alternating 4nm thick layers of molybdenum and tungsten. Uniaxial tensile testing was performed using a standard Instron tensile testing machine, followed by optical analysis of specimen fracture surfaces. Fracture toughness ranged from 2.4 to 9.5MPa(m)1/2, and tensile strengths were observed from 126MPa to 883MPa. Control of mechanical properties was demonstrated by an increase in the upper bound fracture toughness from 2.7 to 9.5MPa(m)1/2 when the tough layer thickness was increased from 1μm to 5μm.

Effect of the Stretch Rate During Uniaxial Testing on the Mechanical Properties of Prolene®

2012 ◽  
Author(s):  
T. M. Bazi ◽  
A. H. Ammouri ◽  
R. F. Hamade
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Relative Elongation ◽  
Testing Machine ◽  
Peak Load ◽  
Displacement Rate ◽  
Uniaxial Tensile ◽  
P Value ◽  
Stretch Rate ◽  
Uniaxial Tensile Testing

We assess the effects of stretch rate on the mechanical properties of Prolene® (Ethicon, Gynecare, Somerville, NJ, USA), a knitted polypropylene mesh. Prolene®, consisting of macroporous knitted polypropylene, is considered here as a suitable proxy to midurethral tape (MUT) as well as to many other prosthesis products used in surgery applications. Such products are utilized to treat urine incontinence, pelvic organ prolapse, as well as hernia in humans. Of the mechanical properties of special significance are the following three properties: peak load (N), extension (%) at peak load, and linear stiffness (N/mm). Uniaxial tensile testing was performed on mesh samples on a universal testing machine and involved loading different samples at 5 cross-head speeds of: 1, 10, 50, 100, and 500 mm/min. The corresponding properties were measured under these 5 conditions. In order to minimize damage to the specimens at the jaws, special dual action pneumatically operated grips with rubber faced jaws were used to hold the samples in place. The effectiveness of these grips was illustrated by the fact that none of the failed samples broke at grips. Statistically significant findings suggest an increasing trend for Prolene® stiffness vs. stretch rate (R2 = 0.9679; two-tailed p value = 0.0025) where the stiffness increases 26.2% when increasing the displacement rate from 1 to 500 mm/min. For extension (%) at peak load, a decreasing trend was found vs. stretch rate (R2 = 0.81; two-tailed p value = 0.037) where increasing the displacement rate from 1 mm/min to 500 mm/min corresponds to a 22% decrease in the relative elongation of the mesh. No statistically significant dependence of peak load on stretch rate was found. These findings may help workers in the biomedical field develop suitable uniaxial tensile testing protocols of such materials.

Structure Assessment Using Instrumented Indentation: Strength, Toughness and Residual Stress

2018 ◽  
Author(s):  
Dongil Kwon ◽  
Jong Hyoung Kim ◽  
Ohmin Kwon ◽  
Woojoo Kim ◽  
Sungki Choi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Residual Stress ◽  
Tensile Properties ◽  
Hole Drilling ◽  
Uniaxial Tensile ◽  
Small Scale ◽  
Specimen Preparation ◽  
Instrumented Indentation ◽  
Uniaxial Tensile Testing

The instrumented indentation technique (IIT) is a novel method for evaluating mechanical properties such as tensile properties, toughness and residual stress by analyzing the indentation load-depth curve measured during indentation. It can be applied directly on small-scale and localized sections in industrial structures and structural components since specimen preparation is very easy and the experimental procedure is nondestructive. We introduce the principles for measuring mechanical properties with IIT: tensile properties by using a representative stress and strain approach, residual stress by analyzing the stress-free and stressed-state indentation curves, and fracture toughness of metals based on a ductile or brittle model according to the fracture behavior of the material. The experimental results from IIT were verified by comparing results from conventional methods such as uniaxial tensile testing for tensile properties, mechanical saw-cutting and hole-drilling methods for residual stress, and CTOD test for fracture toughness.

Mechanical Characterization of Polymer Nanowires Using MEMS

2006 ◽  
Author(s):  
B. A. Samuel ◽  
Bo Yi ◽  
R. Rajagopalan ◽  
H. C. Foley ◽  
M. A. Haque
Keyword(s):  
Mechanical Properties ◽  
Tensile Testing ◽  
Furfuryl Alcohol ◽  
Mechanical Characterization ◽  
Uniaxial Tensile ◽  
Testing Device ◽  
Uniaxial Tensile Testing ◽  
Polymer Nanowires

We present results on the mechanical properties of single freestanding poly-furfuryl alcohol (PFA) nanowires (aspect ratio > 50, diameters 100–300 nm) from experiments conducted using a MEMS-based uniaxial tensile testing device in-situ inside the SEM. The specimens tested were pyrolyzed PFA nanowires (pyrolyzed at 800° C).

scholarly journals Evaluation of anisotropy of mechanical properties of carbon steel flat products

2020 ◽  
Vol 24 (5) ◽  
pp. 1007-1018
Author(s):  
Tatiana Osipok ◽  
◽  
Semen Zaides ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Tensile Testing ◽  
Transverse Direction ◽  
Longitudinal Direction ◽  
Structural Heterogeneity ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Metallic Inclusions ◽  
Anisotropy Of Mechanical Properties

The purpose of the article is to establish experimentally the effect of material inhomogeneity on the characteristics of strength ( σ в, σ 0.2) and plasticity (δ) on example of a rolled steel sheet. Uniaxial tensile testing was carried out on flat samples of hot-rolled sheet made of St3 alloy cut in three directions relative to rolling: along, across and at the angle of 450. The heterogeneity of structure was established by studying the fracture surface of the destroyed samples after tensile testing. A metallographic research and micromechanical testing (measurement of microhardness) of sections parallel to the fracture surface were carried out as well. The uniaxial tensile testing of flat samples resulted in obtaining the values of the characteristics of strength ( σ в, σ 0.2) and plasticity (δ). The analysis of fracture patterns, microstructure and microhardness values of the material allowed to reveal the structural heterogeneity caused by the presence of fibrousness and a banded ferrite-pearlite structure oriented along the deformation direction. The formation reason of the latter was the presence of oriented non-metallic inclusions - elongated plastic sulfides. The study determined that the material under investigation features the anisotropy of mechanical properties and structural heterogeneity. The values of the ultimate strength ( σ в) and yield strength ( σ 0.2) decrease from the longitudinal direction to the transverse direction (relative to the rolling direction) and vice versa (from the transverse to longitudinal direction) in the first case probably due to the influence of non-metallic inclusions (plastic sulfides) and, as a result, the banded ferrite-pearlite structure; in the second case due to the influence of fiber direction. The values of the relative elongation (δ) decrease from the longitudinal direction to the direction at an angle of 450 and then increase to the transverse direction as a result of different hardening of the material during plastic deformation. This is proved by the obtained microhardness values of the investigated sections and the values of the maximum applied loads during the tensile test. The obtained values are obviously the result of the influence of fiber orientation relative to the existing maximum tensile stresses.

scholarly journals STUDY ACOUSTIC EMISSION SIGNALS AT TENSION STEEL 20

2021 ◽  
Vol 83 (2) ◽  
pp. 188-197
Author(s):  
A.V. Ilyakhinskii ◽  
V.M. Rodyushkin ◽  
D.A. Ryabov ◽  
A.A. Khlybov ◽  
V.I. Erofeev
Keyword(s):  
Acoustic Emission ◽  
Tensile Testing ◽  
Dirichlet Distribution ◽  
Failure Process ◽  
Testing Machine ◽  
Amplitude Distribution ◽  
Self Organization ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Steel 20

An investigation was made of acoustic emission signals during uniaxial tensile testing of flat specimens of steel 20 used for parts of welded structures with a large volume of welding, as well as pipelines, collectors and other parts operating at temperatures from –40 to 450 °C under pressure. Tensile testing with simultaneous registration of acoustic emission was carried out on a universal testing machine manufactured by Tinius OIlsen Ltd, model H100KU, at a movement speed of the active gripper of 0.05 meters per minute. Registration of AE signals was carried out using wideband GT350 sensors from GlobalTest and an analog-to-digital converter NationalInstruments 6363X with subsequent storage of the registration results in the form of a time series in the computer memory. A comparative analysis of the amplitude distribution of the AE signal for the area of the yield area and the area of destruction was carried out according to the value of information entropy, fractal dimension, and self-organization parameter. It was found that the parameter of self-organization of the amplitude distribution of the signal is the most informative in describing the processes associated with acoustic emission. As additional information, it is advisable to use data on the structure of the self-organization parameter. The results obtained indicate the possibility of using the statistical model of the Dirichlet distribution as a model of processes associated with the appearance of acoustic emission signals from sources of incipient and developing defects during routine tests of products made of structural carbon high-quality steels with a pearlite-ferrite structure. The paper presents a version of the model and modeling algorithms for FE-modeling corrosion cracking processes in structural elements loaded by pressure and exposed to aggressive corrosion media. To assess the effectiveness of the present models and algorithms, the failure process of a thin-walled tubular specimen partly submerged into a chlorine-containing liquid and loaded by axial tension is numerically modeled.

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

2002 ◽  
Vol 62 (1) ◽  
pp. 73-81 ◽  
Author(s):  
J. M. García Páez ◽  
A. Carrera ◽  
E. Jorge Herrero ◽  
I. Millán ◽  
A. Rocha ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Tensile Testing ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Chemically Treated
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