Experimental definition of a failure model for the tribological behaviour of polytetrafluoroethylene bronze compounds

2009 ◽  
Vol 223 (5) ◽  
pp. 807-815 ◽  
Author(s):  
I Gódor ◽  
Z Major ◽  
Sz Vezér ◽  
F Grün
Keyword(s):  
Test System ◽  
Failure Model ◽  
Micro Structure ◽  
Tribological Behaviour ◽  
Component Level ◽  
High Chemical ◽  
Similar Composition ◽  
Definition Of ◽  
Microscopy Techniques ◽  
Laboratory Specimen

Because of their high chemical and thermal resistance and advantageous friction behaviour, polytetrafluoroethylene (PTFE) compounds are frequently used in various engineering applications, especially for pressurized seals. To adjudge the applicability, and to establish a reliable ranking of various compounds with similar composition and micro-structure for tribological systems, a number of bronze-particle-filled PTFE materials (PTFE-Bz compounds) were investigated with a seal test system at the component level. The two best performing materials in these component tests, termed PTFE-Bz9 and PTFE-Bz14 in this article, were then selected for further, more detailed thermo-mechanical and tribological investigations on a laboratory specimen level. Furthermore, extensive failure analysis of both the worn seals and the test specimens were carried out using laser confocal and scanning electron microscopy techniques. Finally, based on the experimental results a model for describing the functionality and of the failure behaviour of these materials was developed and described.

scholarly journals ThE uSE of AbErrAnT METhylATEd gEnES SEPT9 And VIM for clInIcAl dIAgnoSIS of colorEcTAl cAncEr

2016 ◽  
Vol 7 (4) ◽  
pp. 15-20
Author(s):  
O I Brovkina ◽  
M G Gordiev ◽  
D S Khodyrev ◽  
A G Nikitin ◽  
A V Averyanov
Keyword(s):  
Colorectal Cancer ◽  
High Sensitivity ◽  
Test System ◽  
Aberrant Methylation ◽  
Adjacent Tissue ◽  
Epigenetic Events ◽  
Combined Use ◽  
Ras Family ◽  
Definition Of ◽  
Tumor Dna

Definition of epigenetic disorders is important for early diagnosis of colorectal cancer. To obtain a model of diagnostic test system with high sensitivity and specificity, we determined the frequency of methylation in SEPT9 and VIM genes. Epigenetic events also were compared with mutations in the RAS family genes. It was confirmed the presence of aberrant methylation in SEPT9 and VIM genes in tumor cells. DNA of tumor samples was significantly more methylated than samples with DNA from adjacent tissue (P = 8,67E-19 for SEPT9 gene and P=8,68E-19 for VIM gene). In the group of patients carried mutations in KRAS or NRAS genes tumor DNA significantly more methylated in gene SEPT9 (P = 0.0018), in contrast to the tumor DNA from patients not carried mutations. We have demonstrated that the combined use of methylation markers can improve the sensitivity of the test systems used in the diagnostics of colon cancer.

Shock environment design for space equipment testing

2016 ◽  
Vol 231 (6) ◽  
pp. 1154-1167 ◽  
Author(s):  
OMF Morais ◽  
CMA Vasques
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Test System ◽  
Test Apparatus ◽  
Shock Test ◽  
Shock Testing ◽  
Test Parameters ◽  
Shock Environment ◽  
Definition Of

The main specification in the verification by testing of space hardware vulnerability to shock excitations is the shock response spectrum. Although it compiles the most relevant information needed to describe the overall shock environment characteristics, shock testing still poses various difficulties and uncertainties concerning the suitability and operation of the shock test system used, and the adequate definition of the underlying test parameters. The approach followed from the interpretation of typical shock testing specifications to the development, validation, and characterization of the developed shock test system, including the definition and design of the relevant parameters influencing the attained shock environment, is described in this paper. The shock testing method here presented consists of a pendular in-plane resonant mono-plate shock test apparatus where the structural response of the ringing plate depends upon well-defined controllable parameters (e.g. impact velocity, striker shape, mass, and contact stiffness), which are parametrically determined to achieve the target shock environment specification. The concept and analytical model of two impacting bodies are used in a preliminary analysis to perform a rigid body motion analysis and contact assessment. A detailed finite element model is developed for the definition of the ringing plate dimensions, analysis of the plate dynamics and virtual shock testing. The assembled experimental apparatus is described and a test campaign is undertaken in order to properly characterize and assess the design and test parameters of the system. The developed shock test apparatus and corresponding finite element model are experimentally verified and validated. As a result of this study, a reliable finite element modeling methodology available for future shock test simulation and prediction of the experimental results was created, being an important tool for the adjustment of the shock test input parameters for future works. The developed shock test system was well characterized and is readily available to be used for shock testing of space equipment with varying specifications.

scholarly journals On the relationship between neck length and bond radius during compression of snow

1991 ◽  
Vol 37 (126) ◽  
pp. 203-208 ◽  
Author(s):  
R. L. Brown ◽  
M. Q. Edens
Keyword(s):  
Two Dimensional ◽  
Micro Structure ◽  
Neck Length ◽  
Geometric Effect ◽  
Section Data ◽  
The Third ◽  
Surface Section ◽  
Definition Of ◽  
The Relationship ◽  
Dimensional Surface

AbstractIn an earlier study on the variations in micro-structure during large volumetric deformations of snow, the authors observed that, contrary to expectations, the length of necked regions connecting adjacent grains did not necessarily decrease during compression. Rather, there was no discernible or predictable change in neck length, in some cases increasing and in others decreasing. Further evaluations of the data and an analysis of the mechanics of neck deformation determined that the process is complicated by three different effects: (1) increase in coordination number (number of bonds per grain), (ii) plastic deformation of the neck, and (iii) a geometric effect determined by bond growth and grain geometry. It is found that the first two effects tend to decrease the neck length and that the third produces an increase in mean neck length. A set of coupled differential equations is developed describing the variation of neck length and bond radius, and solved numerically for conditions consistent with the experimental data. Calculated results agree well with the data for the bond radius but the results for the neck length are less satisfactory. Reasons for this lie with difficulty in making accurate measurements of mean neck length from two-dimensional surface-section data and in the criteria for the definition of necks.

scholarly journals Definition of Women Reproductive Tract Microflora Composition Using Test-System “Femoflor-17”

2015 ◽  
Vol 77 (5) ◽  
pp. 87-94 ◽  
Author(s):  
T.V. Sklyar ◽  
◽  
O.V. Krysenko ◽  
O.S. Voronkova ◽  
M.G. Papiashvili ◽  
...  
Keyword(s):  
Reproductive Tract ◽  
Test System ◽  
Definition Of

scholarly journals Failure of a Fiber Composite Lamina Under Three-Dimensional Stresses

1999 ◽  
Author(s):  
Steven J. DeTeresa
Keyword(s):  
Fiber Composite ◽  
Three Dimensional ◽  
Uniaxial Stress ◽  
Failure Criteria ◽  
Fiber Composites ◽  
Test System ◽  
Failure Model ◽  
Pressure Test ◽  
Using Data ◽  
Carbon Fiber Epoxy

Abstract The efficient use of thick-section fiber composites requires a proven three-dimensional failure model. Numerous failure criteria have been proposed, but the lack of critical experimental results makes it difficult to assess the accuracy of these models. It is shown that the various predictions for failure of a lamina due to the simple state of uniaxial stress plus superposed hydrostatic pressure are disparate. These differences are sufficient to allow evaluation of failure criteria using data that has the normal scatter found for composite materials. A high-pressure test system for fiber composites is described and results for the effects of pressure on the transverse and longitudinal compression strengths of a carbon fiber/epoxy lamina are discussed. Results are compared with a few representative failure models.

SEROLOGICAL DIAGNOSIS OF PERTUSSIS IN OLDER PERSONS

2020 ◽  
Vol 65 (8) ◽  
pp. 492-495
Author(s):  
T. A. Skirda ◽  
O. Yu. Borisova ◽  
M. S. Petrova ◽  
A. B. Borisova ◽  
S. Yu. Kombarova
Keyword(s):  
Blood Serum ◽  
Threshold Level ◽  
Test System ◽  
Serum Samples ◽  
Pertussis Infection ◽  
Diagnostic Center ◽  
Group 2 ◽  
Definition Of ◽  
Level Group ◽  
Group 1

The aim of the work was to assess the effectiveness of serodiagnosis of pertussis in people over 50 who complained of prolonged cough. The study included 30 patients over the age of 50 who applied to the consultative diagnostic center complaining of a prolonged cough in the period from 2015 - 2020. Blood serum samples were investigated in enzyme immunoassay with the definition of antitussive antibodies of three classes - IgM, IgG, IgA in the commercial test system RIDASCREEN (R-Biopharm AG, Germany). It was found that in the serum samples of individuals over the age of 50, IgM antibodies above the threshold level were not detected. Patients were divided into two groups - with IgG and IgA antibodies above the threshold level (group 1) and below the threshold level (group 2). In the first group, in 83.3% and 61.1% of patients, the levels of antibodies of the IgG and IgA class significantly exceeded the threshold level (189.8 ± 16.7 U / ml and 290 ± 20 U / ml, respectively), which indicated a pertussis infection; in 5.6% and 38.9% of patients, IgG and IgA class antibodies slightly exceeded the threshold level (20 U / ml and 43 ± 2.3 U / ml, respectively), which indicated a dying infection. In the second group, in 100% of patients, antibodies of the IgM and IgA classes were determined below threshold levels, and IgG antibodies were detected in 58.3% of individuals at low rates, which corresponded to the natural immunological background of individuals not infected with pertussis pathogen. Therefore, in the presence of a prolonged cough in adults, it is advisable to study blood serum samples for the presence of antitussive antibodies of three classes, which is especially important when people of older age live in families with young children and pregnant women

Study on Physical and Mechanical Characteristics of Q2 Loess and Micro-Structure Properties in Li-Shan

2014 ◽  
Vol 1065-1069 ◽  
pp. 1846-1849 ◽  
Author(s):  
Ying Wang ◽  
Pan Pan Yang
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Practical Significance ◽  
Basic Unit ◽  
Micro Structure ◽  
Basic Characteristics ◽  
Microscopy Techniques ◽  
Xi’An City ◽  
Scanning Electron ◽  
Physical And Mechanical Characteristics

The physical and mechanical properties and microstructure of Q2loess are of great theoretical and practical significance. Through studying these properties which Q2loess samples are taken in the Xi'an city of Lin-tong District of Mount Li, the results show that: (1)Natural water content, wet density, liquid and solid index, shear strength, collapsible coefficient compressive modulus; (2)By means of the scanning electron microscope to study the picture of the loess micro-structure, there are some preliminary understanding of micro-structure’s basic characteristics; (3)Using scanning electron microscopy techniques to observe the loess micro-structure, As the performance of the loess micro-structure’s basic unit-body and its arrangement form, the loess micro-structure is the reflection of its physical and mechanical properties, Meanwhile the change of physical and mechanical properties also show the unstability of the loess micro-structure.

Product Architecture Definition and Analysis Using Matrix-Based Multiple-Domain Approaches

2009 ◽  
Author(s):  
Frank Deubzer ◽  
Udo Lindemann
Keyword(s):  
Solution Space ◽  
Levels Of Abstraction ◽  
Component Level ◽  
Design Synthesis ◽  
Levels Of Detail ◽  
Functional Product ◽  
Innovative Solutions ◽  
Definition Of ◽  
Different Levels ◽  
Multiple Domain

Design Synthesis is most commonly supported by creativity methods based on functional product representations. As the design of a new product is in most cases following a predecessor, designers do not start from scratch. The mentioned circumstances enable the support of design synthesis by application of design rules or grammars. The use of rules by automated algorithms allows for the systematical derivation of variations of a product. Algorithms are meant to enable innovative solutions by recommending a great variety of variants to give the designers new impulses for product design. As a downside, the rules for the algorithms have to be described in advance, and thus are inheriting known components and functional structures. The identification of potentials and constraints for improvement of a product’s architecture requires detailed analysis. New solutions are often depending on novelties on different levels of abstraction (for example system, subsystem or component level). Algorithmic procedures usually are not able to allow for this comprehensive task. Thus, automatized mechanisms can only deliver limited innovative solutions. Common methods for the definition of innovative solutions, such as functional modeling methods, the TRIZ methodology, or the Morphological Matrix require accompanying analysis and the fixation onto one level of detail as well. To solve this dilemma, we propose an approach combining powerful analysis methods, required for the identification of potentials and constraints within product architectures on the one hand and the systematic definition of new solutions by systematic and partially automatized methods on the other hand. Exhaustive literature research has pointed out several methods, whose application can benefit a comprehensive approach. Amongst them is the definition of functional models, design synthesis by automatized system definition as well as the analysis of product architectures by the use of Design Structure Matrix and Multiple-Domain Matrix Approaches. The proposed approach should allow for the support of radical innovations by considering the overall product structure. Goal of the approach is the consideration of different levels of detail and the analysis of a comprehensive solution space compared to the definition of discrete solutions delivered by common methods. As a result, the approach is applied to different products on different levels of detail and the publication points out the potential and outcome: the systematic definition of a comprehensive solution space, new solutions as a result of comparison and evaluation of the solution space, the widening of the solution space, and a comprehensive evaluation of results.

Effect of the Oxidation on the Tribological Behaviour of Steels

2020 ◽  
Vol 22 (4) ◽  
pp. 1247-1260
Author(s):  
Kaid-Ameur Djilali ◽  
Ahmed Hebbar
Keyword(s):  
Mathematical Models ◽  
Influential Factors ◽  
Quantitative Methodology ◽  
Tribological Behaviour ◽  
Series Of Experiments ◽  
Definition Of ◽  
Tools And Methods ◽  
Relevant Factors

AbstractThe work presented in this study focus on the application of the method of the plans of experiences (MPE) to the study and the optimization of the quantification of the wear of the steels (XC48, A60) under the effect of a factor of environment in the occurrence Hydrogen. Modeling can draw inspiration from the mathematical models established by the (MPE) in order to analyze more deeply the phenomenon of the wear while taking account of the various relevant factors [1].The MPE, introduced is a consistent set of tools and methods algèbro-statistics to establish and analyze the relationships in the quantities studied (responses) and their sources of variations (factors) [2]. This analysis may be qualitative: study of “screening” (determination of influential factors) or quantitative: methodology of the surfaces of answers (variation of responses according to the influential factors). In all cases, it has for the purpose of determination of mathematical models approached the answers expressed in terms of the factors. These models are deducted from the values obtained of series of experiments. The definition of these plans of experiences determines the measurable quality of models. The multiple facets of the MPE are then used as the basis for the development of strategy to optimize [3].

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