Checking and Improvement of the Alignment of Flat Specimen Gripping Devices

2008 ◽  
pp. 136-136-24
Author(s):  
R Fischer ◽  
E Haibach
Keyword(s):  
Flat Specimen

Thermal Effects in Contact Fatigue Under Oscillatory Normal Load

1965 ◽  
Vol 87 (1) ◽  
pp. 177-184 ◽  
Author(s):  
R. A. Burton ◽  
J. C. Tyler ◽  
P. M. Ku
Keyword(s):  
Energy Dissipation ◽  
Dynamic Load ◽  
Normal Load ◽  
Fatigue Cracks ◽  
Thermal Transformation ◽  
Contact Fatigue ◽  
Contact Temperature ◽  
Flat Specimen ◽  
Exponential Relationship ◽  
Specimen Temperature

Experiments are reported wherein contact fatigue was brought about by the application of an oscillatory normal load between a ball and a flat specimen. Plots of the flat-specimen temperature versus time showed that a rapid temperature rise occurred in the initial stage of crack formation, and thus provided an early indication of fatigue. Thermal resistances were measured for the apparatus components as well as the specimen contact. Using these, it was possible to apply the measured flat-specimen temperature to obtain estimates of the contact temperature as well as the energy dissipation rate prior to the incidence of fatigue cracks. It was shown that the contact temperature did not rise sufficiently to produce annealing in the test specimens. Thus, toroidal rings of hardened and softened material in the stressed zone could not be attributed to thermal transformation of the bearing steel. It was also shown that energy dissipation due to cyclic loading varied in approximate exponential relationship with dynamic load, and decreased upon increase of static load when dynamic load was maintained constant.

scholarly journals An innovative fixture for testing the crashworthiness of composite materials

2020 ◽  
Vol 15 (55) ◽  
pp. 76-87
Author(s):  
Lorenzo Vigna ◽  
Iman Babaei ◽  
Ravin Garg ◽  
Giovanni Belingardi ◽  
Davide Salvatore Paolino ◽  
...  
Keyword(s):  
Composite Materials ◽  
Energy Absorption ◽  
Standard Procedure ◽  
Test Procedure ◽  
International Standards ◽  
Experimental Setup ◽  
Flat Specimen ◽  
Specific Energy Absorption ◽  
Impact Energies ◽  
Force Displacement

Despite the growing diffusion of composite materials in automotive and aerospace sectors, a standard procedure for testing their crashworthiness has not been developed yet. At present, the international standards for testing composite materials under impact conditions are not adequate to test their crush behavior. In this paper, a procedure for measuring the energy absorption due to the compressive crushing of a composite flat specimen, along its mid plane, is proposed. The experimental setup requires a fixture to hold the specimen and to avoid its buckling and an instrumented drop weight tower to obtain the force-displacement curves with the aim of calculating the Specific Energy Absorption. The paper will describe the adopted test procedure and some of the features of the newly developed experimental setup. The effectiveness of the procedure is demonstrated by testing several glass fiber-epoxy specimens under different impact energies.

Cryofixation and X-Ray Microanalysis of Thin Cryosections Applied to Biopsies from the Human Prostate

1990 ◽  
Vol 48 (2) ◽  
pp. 348-349
Author(s):  
Kåre E. Tvedt ◽  
Jostein Halgunset ◽  
Gunnar Kopstad
Keyword(s):  
Tissue Sample ◽  
Inorganic Salts ◽  
Flat Specimen ◽  
Biopsy Needle ◽  
X Ray ◽  
Freezing Method ◽  
Specimen Holder ◽  
Biopsy Specimens ◽  
The Press ◽  
Standard Solution

In order to make needle biopsies more readily applicable to cryo-ultramicrotomy and x-ray microanalysis, we have developed a method which permits biopsy specimens to be frozen immediately after removal from the patients, using metal mirror freezing.Then tissue sample is quickly transferred from the biopsy needle to a formvar film which in advance has been supplied with a drop of standard solution containing PVP and inorganic salts. Freezing is performed by clamping the sample between the cylindrical copper jaws of a pair of pliers, precooled in liquid nitrogen (fig.l). The flat specimen is cut in a Reichert-Jung Ultracut/FC4 cryosystem. The section is collected on a grid/retainer assembly, which is mounted inside a. transportable press. Secured between two grids inside the press, the sections are transferred to an external freeze-drier.This system makes it possible to freeze,even small pieces of tissue using the metal mirror freezing method. The pliers produce a flat specimen containing the tissue and the elemental standard, with two well-frozen surfaces which readily can be sectioned using a flat specimen holder.

scholarly journals Insights on Diffraction

2002 ◽  
Vol 10 (2) ◽  
pp. 34-35
Author(s):  
Alwyn Eades
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Flat Specimen ◽  
Kikuchi Lines ◽  
Different Parts

This article presents ideas on some topics related to electron diffraction in the TEM. These are in regard to topics that I have come to think of as standard parts of what it means to do microscopy. However, they represent insights that not all users share (or even agree with, maybe).Kikuchi lines are of great use in orienting a sample. Unfortunately, in modern microscopes, Kikuchi lines are not seen in selected-area diffraction (SAD). This is because immersion lenses send parallel electrons, from different parts of the sample (like the Kikuchi lines from a flat specimen), to different places in the diffraction pattern.

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