scholarly journals Basic Equations Describing Mechanics and Kinematics of a Test Piece-Testing Machine System in Tensile Tests of Single Crystals

1994 ◽  
Vol 58 (11) ◽  
pp. 1263-1270
Author(s):  
Kazuwo Imai
Keyword(s):  
Single Crystals ◽  
Test Piece ◽  
Testing Machine ◽  
Tensile Tests ◽  
Machine System ◽  
Basic Equations

scholarly journals The behaviour of three single crystals of aluminium in fatigue under complex stresses

1935 ◽  
Vol 149 (867) ◽  
pp. 312-326 ◽  
Keyword(s):  
Single Crystals ◽  
Test Piece ◽  
Testing Machine ◽  
Bending Moment ◽  
Stress System ◽  
Pure Bending ◽  
Bending Strain ◽  
Bending Stresses ◽  
Ordinary Type ◽  
New Type

In the ordinary type of Wöhler machine used for testing materials in fatigue under reversed bending stresses, the load system is stationary in space, and variation of the stress system with respect to the test piece is obtained by rotating the test piece. It is, of course, essential to the success of the test that the system of displacements caused by the application of the load system to the test piece should remain stationary in space; but, since the test piece rotates, this requirement can only be fulfilled if the material of the test piece is isotropic. Thus, if an attempt were made to test a single crystal in a Wöhler machine it might be anticipated that either actual elastic antisotropy or the virtual anisotropy due to restricted slip movement would cause the deformation to vary with the orientation of the stress system relative to the axes of the crystal and that "whipping" of the specimen would occur. Three such attempts have indeed been made: but in spite of great care exercised in setting up the specimens and in applying the loads, only in one case, in which the orientation of the crystal was such as to provide effective symmetry about the axis of the specimen, was the test successful. A new type of testing machine recently developed at the N. P. L. for testing specimens in fatigue under systems of combined bending and torsional stresses, differs in principle from the Wöhler machine in that the variation of stress is produced by actual variation of load. In this machine both me test piece and the orientation of the stress system remain stationary, only the magnitude of the stresses being varied. The deformation of the test piece is therefore only that due to one type of stress system fixed in relation to the orientation of the test piece and varying only in magnitude. Moreover, the construction of the machine is such that the strain of the test piece is not required to be of the same type as the stress system applied, e. g ., the application of pure bending moment does not restrict the test piece to pure bending strain and the test piece remains free to twist also if necessary. These conditions render this type of machine perfectly suitable for test on single crystals. Accordingly, tests have been carried out in this machine on three single crystals of aluminium; the first was tested under reversed flexural stresses, the second under reversed torsional stresses and the third under a combination of reversed flexural and reversed torsional stresses.

scholarly journals The Performance of CR180IF and DP600 Laser Welded Steel Sheets under Different Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1553
Author(s):  
Mária Mihaliková ◽  
Kristína Zgodavová ◽  
Peter Bober ◽  
Anna Špegárová
Keyword(s):  
Sheet Steel ◽  
Testing Machine ◽  
Dynamic Test ◽  
Tensile Tests ◽  
Joint Surface ◽  
Strain Rates ◽  
Interstitial Free ◽  
Welded Steel ◽  
Steel Sheets ◽  
Static Tensile

The presented research background is a car body manufacturer’s request to test the car body’s components welded from dissimilar steel sheets. In view of the vehicle crew’s protection, it is necessary to study the static and dynamic behavior of welded steels. Therefore, the influence of laser welding on the mechanical and dynamical properties, microstructure, microhardness, and welded joint surface roughness of interstitial free CR180IF and dual-phase DP600 steels were investigated. Static tensile tests were carried out by using testing machine Zwick 1387, and dynamic test used rotary hammer machine RSO. Sheet steel was tested at different strain rates ranging from 10−3 to 103 s−1. The laser welds’ microstructure and microhardness were evaluated in the base metal, heat-affected zone, and fusion zone. The comprehensive analysis also included chemical analysis, fracture surface analysis, and roughness measurement. The research results showed that the strain rate had an influence on the mechanical properties of base materials and welded joints. The dynamic loading increases the yield stress more than the ultimate tensile strength for the monitored steels, while the most significant increase was recorded for the welded material.

Using Embossing to Create a Fiber Reinforced Honeycomb Composite

2005 ◽  
Vol 127 (2) ◽  
pp. 257-262 ◽  
Author(s):  
William Jordan
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Carbon Fibers ◽  
Flexural Modulus ◽  
Testing Machine ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Hydraulic Testing ◽  
Charpy Impact Toughness ◽  
Bend Tests

This research project used hot embossing to create a strong and tough polymeric based composite structure. A honeycomb type structure was created by pressing small grooves into thin polycarbonate sheets. A trapezoidal die was used to create hexagonal shaped channels in the polymeric sheet. A number of these sheets were then bonded together to form a composite material. Carbon fibers were embedded into the channels in some of the laminates. The embossing process was carried out at an elevated temperature in an environmental chamber attached to an MTS servo hydraulic testing machine. The grooved structure had a 31% to 45% decrease in the apparent density compared to the ungrooved specimens. Bend tests, tensile tests, and Charpy impact tests were performed on laminates made from this material. The specific values of tensile strength, flexural modulus, and Charpy impact toughness were increased. A small percentage of fibers significantly increased both the stiffness and strength of the laminate.

Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet

2013 ◽  
Vol 690-693 ◽  
pp. 211-217
Author(s):  
Jin Gui Qin ◽  
Fang Yun Lu ◽  
Yu Liang Lin ◽  
Xue Jun Wen
Keyword(s):  
Strain Rate ◽  
Testing Machine ◽  
Structural Response ◽  
Tensile Tests ◽  
Dynamic Tests ◽  
Static Tests ◽  
Split Hopkinson Tensile Bar ◽  
Axial Tensile ◽  
Static Tensile ◽  
Cook Model

Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.

Tensile Deformation of Si Single Crystals at High Temperatures

2021 ◽  
Vol 1016 ◽  
pp. 1443-1447
Author(s):  
Tubasa Suzuki ◽  
Masaki Tanaka ◽  
Tatsuya Morikawa ◽  
Yelm Okuyama ◽  
Jun Fujise ◽  
...  
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Stage Ii ◽  
Electron Backscattered Diffraction ◽  
Kink Bands ◽  
Schmid Factor ◽  
Primary Slip System ◽  
Yield Point Phenomenon

Czochralski silicon single crystals were deformed in tensile tests along the direction at between 1173 K and 1373. Yield point phenomenon were observed in the specimens deformed at below 1273 K while continues yield was observed in the specimens deformed at above 1323 K. It is due to the effect of dislocation starvation in the used crystals. Work-hardening rates in stage II were consistent with those reported in fcc crystals such as copper. The onset of stage II was found to be active before the Schmid factor of the second slip system becomes larger than that of the primary slip system. Electron backscattered diffraction images indicated clear kink bands near grips and in the parallel portion. The kink bands were formed at the middle of stage I, which suggest that the formation of kink bands is a trigger of stage II.

Fatigue Properties of Al-Li Plates Joined by Friction Stir Welding

2008 ◽  
Vol 385-387 ◽  
pp. 849-852 ◽  
Author(s):  
Pasquale Cavaliere ◽  
Francesco W. Panella ◽  
Antonio Squillace
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Testing Machine ◽  
Rolling Direction ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Control Mode ◽  
Fatigue Properties ◽  
Amplitude Control ◽  
Friction Stir

Al-Li alloys are characterized by a strong anisotropy in mechanical properties and microstructure with respect to the rolling direction. Plates of 2198 Al-Li alloy were friction stir welded by employing maximum rotation speed: 1000 rev/min and welding speed of 80 mm/min, both in parallel and orthogonal directions with respect to the rolling one. The joints mechanical properties were evaluated by means of tensile tests at room temperature. In addition, fatigue tests performed with a resonant electro-mechanical testing machine under constant amplitude control up to 250 Hz loading, were conducted in axial control mode with R(σmin/σmax)=0.33, for all the welding and rotating speed conditions. The fatigue crack propagation experiments were performed by employing single edge notched specimens.With the aim to characterize the weld performances, both the microstructure evolution at jointed cross sections, related to the welding variables, and the fractured surfaces were respectively analyzed by means of optical and scanning electron microscopy.

Tensile Tests with Flat (Straight) Test-Specimens

1938 ◽  
Vol 11 (1) ◽  
pp. 214-223
Author(s):  
R. Ariano
Keyword(s):  
Test Specimen ◽  
Testing Machine ◽  
American Chemical Society ◽  
Tensile Tests ◽  
Chemical Society ◽  
Ring Test ◽  
Rubber Ring ◽  
Long Time ◽  
Fundamental Objection ◽  
Center Section

Abstract It is of course a well known fact that both ring test-specimens and flat or straight test-specimens are used in testing rubber. Ring test-specimens have for a long time been the most generally used type for testing rubber mixtures, whereas in American laboratories straight test-specimens are preferred. Ring test-specimens are the more convenient to use, but they are open to one fundamental objection, that different parts of the cross section of the rubber are elongated to different extents at any particular moment. Even straight test-specimens are not free from objectionable features. With this type of test-specimen, the inequality in the deformation at any particular instant results from the necessity of having enlarged ends for the testing machine to avoid breakage of the test-specimens in the jaws. It therefore becomes necessary to study systematically the form and dimensions of the end sections of the test-specimens and of the junction of these end sections with the central section, so that the points of rupture will not become localized in the sections in the jaws or close to these sections. As a matter of fact, an extensive investigation of this problem has been made by the Physical Testing Committee of the Rubber Division of the American Chemical Society. By a proper study of the shape of the test-specimen, it is possible to design the test-specimen so that rupture occurs in the center section and therefore so that satisfactory tensile strength measurements are obtained.

scholarly journals Compliance-Derived Strain Determination in Fibre (Bundle) Tests at High Temperatures

1998 ◽  
Vol 7 (3) ◽  
pp. 096369359800700 ◽  
Author(s):  
R. Paar ◽  
P. Bonnel ◽  
M. Steen
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Strain Measurement ◽  
Fibre Bundle ◽  
Testing Machine ◽  
Tensile Tests ◽  
Gauge Length ◽  
Head Displacement ◽  
The Cross ◽  
Strain Determination

In high temperature fibre tensile tests direct strain measurement is not a straightforward task, due to the limited accessibility and the fragile nature of the specimen. A compliance method which allows to determine the true specimen strain within the gauge length from the cross head displacement of the testing machine is presented.

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