Variations in Testing Procedures on the Rotary Flexometer

1976 ◽  
Vol 49 (2) ◽  
pp. 258-277 ◽  
Author(s):  
P. Kainradl ◽  
F. Wolf ◽  
H. Ecker
Keyword(s):  
Fatigue Resistance ◽  
Heat Generation ◽  
Test Method ◽  
Force Amplitude ◽  
Severity Factor ◽  
Testing Procedures ◽  
Deformation Amplitude ◽  
German Standard ◽  
Constant Deformation ◽  
Specimen Center

Abstract The rotary flexometer described in German Standard Proposal DIN 53 533 has been used to determine heat generation and fatigue resistance on homogeneous rubber specimens, laminated specimens, and some containing fabric plies. When a series of compounds having a range of hysteresis or hardness is run at constant deformation amplitude, the ranking is usually inverse to that obtained when run at constant force amplitude. The test method should be chosen to correspond to the proposed use of the compound. Accessories developed permit testing of 10 ×. 10 mm cylindrical specimens as well as conventional 20 × 20 mm cylinders. Temperature measurements in the specimen center have proven to be more precise than those on the free surface or on a clamped surface. Temperature increase during cycling is strictly a function of the viscoelastic properties of the compound. Creep measured at ambient temperature may rate a series of compounds differently than if measured at an elevated temperature. Fatigue resistance is well represented by S-N curves where the logarithm of N, the cycles to failure is plotted as a function of S, the severity factor (deformation amplitude or force amplitude). An inverse relationship exists between rate of heat generation and failure by degradation of the specimen center. The vulcanization system affects fatigue life. The temperature reached during testing of a highly hysteretic material can be minimized by using it as the central layer of a laminated specimen and higher hysteretic materials for the rest of the specimen. The apparatus can be used for testing dynamic adhesion fatigue of rubber-fabric bonds. Failure between plies started as a failure of the bond between rubber and cord.

scholarly journals Laboratory Tests and Analyses of the Level of Vibration Suppression of Prototype under Ballast Mats (UBM) in the Ballasted Track Systems

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 313
Author(s):  
Cezary Kraśkiewicz ◽  
Artur Zbiciak ◽  
Kacper Wasilewski ◽  
Anna Al Sabouni-Zawadzka
Keyword(s):  
Mechanical Model ◽  
Laboratory Tests ◽  
Vibration Suppression ◽  
Track Structure ◽  
European Standard ◽  
Static And Dynamic Characteristics ◽  
Vibration Isolators ◽  
Testing Procedures ◽  
Ballasted Track ◽  
German Standard

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel 4-DoF mechanical model of the track structure with UBM was developed. The novelty of this study consists in the comparison of two testing procedures: a procedure based on the popular German standard DIN 45673-5 and a new European standard EN 17282, released in October 2020. Major discrepancies were demonstrated in the determined values of the static and dynamic characteristics using both approaches—especially in reference to the mats with higher stiffness.

scholarly journals The influence of an applied standard test method on a measurement of concrete stabilized secant modulus of elasticity

2018 ◽  
Vol 163 ◽  
pp. 07001
Author(s):  
Lucyna Domagała ◽  
Justyna Dobrowolska
Keyword(s):  
Modulus Of Elasticity ◽  
Lightweight Aggregate ◽  
Standard Test ◽  
Normal Weight ◽  
Test Method ◽  
Hardened Concrete ◽  
Secant Modulus ◽  
Testing Procedures ◽  
Standard Test Method ◽  
The Difference

The paper focuses on the influence of the standard test method applied to determine the concrete stabilized secant modulus on a specified value. The new European Standard EN 12390-13 for testing hardened concrete accepts two methods (A and B) for the determination of the secant modulus of elasticity in compression. The aim of the research was to establish how different testing procedures affect a measured value of modulus of elasticity. Four structural concrete series: two lightweight aggregate concretes and two normal-weight ones were subject to tests of moduli of elasticity determined by both standard methods, as well as compressive strength and density. The carried out tests revealed that the procedure of testing modulus of elasticity influenced a measured value. Method A led to higher values of modulus in relation to Method B, irrespective of concrete density and strength. Nevertheless, a certain relationship between the concrete structure homogeneity and the difference in results of moduli determined by both methods may be observed.

Shock Absorbing Characteristics of Floors Used for Dance Exercise

1988 ◽  
Vol 4 (3) ◽  
pp. 282-305 ◽  
Author(s):  
Peter R. Francis ◽  
Michael Leigh ◽  
Aldis Berzins
Keyword(s):  
Standardized Test ◽  
Test Method ◽  
Complex Nature ◽  
Data Sets ◽  
Acceleration Time ◽  
Testing Procedures ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Additional Procedure

The Standardized Test Method for Shock-Absorbing Properties of Playing Surface Systems and Materials (ASTM F-355) was used to evaluate the shock absorbing characteristics of 13 floors used for dance exercise. Acceleration-time histories indicated that the floors differed markedly in their shock absorbing behavior. The complex nature of the acceleration-time histories led to the conclusion that descriptors that have previously been used to quantify shock absorbing data were inadequate for the floors examined in this investigation. An additional procedure was devised in order to examine potentially injurious stresses on a performer while executing a common dance exercise movement performed on each of the 13 floors tested. It was concluded that the two testing procedures evaluated differing aspects of the shock absorbing mechanisms involved in dance exercise. However, a tentative relationship between the two corresponding data sets provided some support for the retention of ASTM F-355 as a reproducible test for the shock absorbing characteristics of floors.

scholarly journals Validation of Rock Testing Methods in Determination of Apparent Density

2018 ◽  
Vol 66 ◽  
pp. 02003
Author(s):  
Joanna Hydzik-Wiśniewska ◽  
Sebastian Olesiak
Keyword(s):  
Research Methods ◽  
Apparent Density ◽  
Test Method ◽  
Systematic Evaluation ◽  
Test Results ◽  
Factors Affecting ◽  
Testing Procedures ◽  
Precision Evaluation ◽  
Mathematical Formulas

Research on the physical properties of rock materials and aggregates used for construction should be based on standardized methods. Whereas scientific research is focused more on the development of new methods, testing and evaluation of new properties, etc. In case of own testing procedures and standardized but modified methods, they should be validated before being put into use. Validation is the confirmation of the ability to designate that method and tests its usefulness. In order to investigate the method's possibilities, the following assessment methods can be used: calibration or precision evaluation using reference standards or reference materials, systematic evaluation of factors affecting the result, resistance of the test method to variability of controlled parameters, comparison of test results obtained by various methods, inter-laboratory comparisons, and uncertainty of measurement. The paper presents mathematical formulas allowing to evaluate the precision of research methods and the consistency of results, which are the basis for validation of research methods. In the practical part of the article, own method of apparent density testing, was validated based on the analysis of repeatability, internal laboratory reproducibility and between laboratory reproducibility.

Improvements of Testing Procedures for Concrete Coefficient of Thermal Expansion

2005 ◽  
Vol 1919 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Moon Won
Keyword(s):  
Thermal Expansion ◽  
Coarse Aggregate ◽  
Coefficient Of Thermal Expansion ◽  
Test Procedure ◽  
Concrete Pavement ◽  
Test Method ◽  
Pavement Performance ◽  
Portland Cement Concrete ◽  
Testing Procedures ◽  
Accuracy And Repeatability

The coefficient of thermal expansion (CTE) of concrete has a significant effect on the performance of portland cement concrete pavement. Concrete with a higher CTE is more prone to cracking, additional warping, and spalling. To improve PCC pavement performance, several districts of the Texas Department of Transportation (TxDOT) currently limit the CTE of concrete. To support this policy, efforts have been made to improve the accuracy and repeatability of the testing procedures for CTE. The current AASHTO Test Method TP 60 has been evaluated, its shortcomings identified, and improvements made. The improvements include CTE determination from regression analysis of temperature and displacement measurements. The effects of a number of variables on concrete CTE were investigated. The effect of the rate of heating and cooling is negligible. Concrete age and specimen size also have a negligible effect. Coarse aggregate content in the concrete mix has an effect on the test results. This test procedure was used to evaluate coarse aggregates from 32 sources in Texas. The results show that coarse aggregate type has a significant effect on concrete CTE. The proposed testing procedure for concrete CTE provided more accurate results than the AASHTO TP 60. TxDOT plans to implement this test procedure and to develop appropriate steel design standards for continuously reinforced concrete pavement and other construction-related requirements such as different curing methods for concrete with varying CTEs. This implementation should result in better concrete pavement performance.

Experimental Testing Techniques for Kevlar® Fiber Brush Seals

2009 ◽  
Author(s):  
Eric J. Ruggiero ◽  
Jason Allen ◽  
Mark Lusted
Keyword(s):  
Heat Generation ◽  
Experimental Testing ◽  
Aramid Fiber ◽  
Successful Operation ◽  
Blow Down ◽  
Pressure Drops ◽  
Testing Procedures ◽  
Order Of Magnitude ◽  
Frictional Forces ◽  
Brush Seals

Non-metallic brush seals, and more specifically, Kevlar® (aramid) fiber brush seals, are an emerging sealing technology in low-pressure, low temperature applications. Compared to metallic brush seals, aramid fibers are an order of magnitude smaller in diameter and consequently offer much tighter sealing capability. Further, their compliant nature requires minimal pressure drops across the seal to encourage blow-down of the bristle pack onto the rotor during operation. Similarly, their compliant nature also enables the bristle pack to correct for alignment issues and to recover from radial growth transients of the rotor. Proper design of the bristle pack stiffness is critical to the successful operation of the seal. If the seal is designed to be too soft, frictional forces prohibit the recovery of the bristle pack if pressed away from the rotor. Conversely, if designed too stiffly, then the heat generation at the sliding interface of the seal accelerates the degradation of the seal. The goal of the present paper is to present the experimental techniques developed to guide the design of aramid fiber brush seals. Two experimental test methodologies will be presented: a direct stiffness measurement and a heat generation measurement. Both testing procedures have been used to successfully design seals for various GE turbomachinery products.

scholarly journals Low-cost test setup for motorcycle protective clothing abrasion examination

2021 ◽  
Vol 2 (2) ◽  
pp. 196-207
Author(s):  
Dietrich Spädt ◽  
Imane Moulefera ◽  
Al Mamun ◽  
Marah Trabelsi ◽  
Lilia Sabantina
Keyword(s):  
Abrasion Resistance ◽  
Protective Clothing ◽  
Low Cost ◽  
Good Alternative ◽  
Test Method ◽  
Road Accidents ◽  
Testing Procedures ◽  
Test Standards ◽  
Physical Injuries ◽  
Different Types

The personal protective equipment and protective clothing for motorcyclists reduce physical injuries to victims of road accidents. Therefore, it is important that the protective clothing complies with a number of test standards, which must be taken into account during the manufacturing process. However, the EN17092-1 to 6 standard does not necessarily correspond to a real accident situations and these testing procedures are time consuming. In this study, a simple and inexpensive self-constructed device for testing the abrasion resistance of motorcycle protective clothing was developed and evaluated. Different types of textiles and leather with and without coating were tested and compared. According to the results of this study, not only leather but also textiles offer good abrasion resistance results. The results show that the strength of an impact significantly changes the abrasion resistance. The developed test method can provide a good alternative as a low-cost and simple test method of abrasion resistance of motorcycle protective clothing.

scholarly journals Microbial Air Samplers for Meaningful Cleanroom Environmental Monitoring

2021 ◽  
Author(s):  
Tim Eaton
Keyword(s):  
Collection Efficiency ◽  
Performance Testing ◽  
Poor Performance ◽  
Test Method ◽  
Biological Efficiency ◽  
Testing Procedures ◽  
Additional Information ◽  
Air Sampler ◽  
Airborne Microbes ◽  
Efficiency Test

Airborne microbiological concentrations within pharmaceutical cleanrooms are determined by sampling and to maximise the detection of any airborne microbes, it is essential that the sampling is undertaken in locations where there is greatest contamination risk using air samplers that have a verified and appropriate performance. Sampler performance can be assessed by review of both the physical and biological collection efficiencies that are determined by testing. The physical collection efficiency is the ability to collect particles of various sizes and the biological collection efficiency assesses the collection of viable microbes that includes the losses caused by the physical collection efficiency and the detrimental effect that the sampling has on the viability of the captured microbes. Due to the limitations of the established biological collection efficiency test method, this efficiency is only determined for microbes of sub-micron size which are not representative of the larger microbe-carrying particles typically present with cleanrooms. Samplers with a low physical collection efficiency for sub-micron particles are likely to have a poor performance when this test method is utilised and in an attempt to remove this bias from the testing the ‘biological efficiency’, is often reported. This is a measure of the likelihood that any captured microbes would survive, but is often mistaken for the biological collection efficiency and samplers may be utilised in the false belief that they have an appropriate performance. This article provides information regarding air sampler performance testing and reviews the test results reported by the same independent specialist testing company, therefore negating issues resulting from different testing methods, for three different air samplers. The results that are used to determine the ‘biological efficiency’ are examined to provide information relating to the biological collection efficiency of each sampler and to also provide additional information relating to the physical collection efficiency. Improvements to enhance the air sampler testing procedures, to enable a better direct comparison of the performance of different samplers, are suggested.

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