Einfluss einer Reibhysterese auf selbsterregte Schwingungen von Partikel-Festkörper-Systemen

2021 ◽  
Vol 68 (3-4) ◽  
pp. 50-57
Author(s):  
Thomas Fürstner ◽  
Matthias Kröger
Keyword(s):  
Numerical Model ◽  
Time Dependent ◽  
Smooth Transition ◽  
Test Rig ◽  
Friction Behavior ◽  
Stick Slip ◽  
Dependent Behavior ◽  
Average System ◽  
Pmma Particles ◽  
Solid System

The influence of a friction hysteresis on the self-exciting in a particle-solid-system will be investigated by experiments and a numerical model. For this, a test rig will be presented. This test rig allows to measure the actual acting friction force. Furthermore, a numerical model will be presented which has a differentiation between a time-dependent friction behavior in sliding and sticking. Bigger differences can be observed in the system behavior – even with a quality similar curve of the measured friction hysteresis. For example, in a system with PVC-W particles exists a sharp boundary between an area of stable stick-slip oscillation and an area of subsiding oscillation. In comparison to this, a system with PMMA particles has a smooth transition region between these two areas. The followed simulation studies shown, that the selfexciting mechanism is a complex interaction between the time-dependent behavior during the sliding and sticking and the external average system velocity.

Experimental and Numerical Investigation of Erosive Change of Shape for High-Pressure Compressors

2015 ◽  
Author(s):  
Marcus Schrade ◽  
Stephan Staudacher ◽  
Matthias Voigt
Keyword(s):  
High Pressure ◽  
Aluminum Alloy ◽  
Numerical Model ◽  
Erosion Rate ◽  
Time Dependent ◽  
Jet Engines ◽  
Test Rig ◽  
Dependent Change ◽  
Time Dependent Change ◽  
Erosive Change

Compressor performance and maintenance characteristics of jet engines are highly influenced by erosion caused by ingested, solid particles. For a meaningful prediction of these characteristics, an adequate modeling of the erosive change of shape of compressor blades is necessary. This article investigates the erosive change of shape of two different specimens (cylinder and compressor blade) out of aluminum alloy EN AW-6060 both experimentally and numerically. The erosion experiments were performed with a test rig using different amounts of standardized Arizona Test Dust A3 (particle sizes of 1–120μm) to acquire the time-dependent change of shape of the specimens. The shape of the specimens was digitized using a strip projection technique before and after each erosion test. The test rig provides boundary conditions specific for first stages of axial high-pressure compressors of jet engines in terms of relative fluid velocity (350ms−1) which is the main parameter of erosion. Numerical results were obtained with a model predicting the time-dependent change of shape of the specimens in 2D. The numerical model uses erosion rate curves that were experimentally determined in the same test rig using flat plates out of the aforementioned aluminum alloy. Thus, we were able to investigate experimentally the time-dependent erosive change of shape of the specimens and compare it with the numerical predictions. We conclude that the numerical model is a valid approach to predict erosive change of shape for different specimen geometries and materials, when erosion rate curves are available for these materials.

Time-dependent behavior of nitric oxide excited states under the effect of electron impact

2021 ◽  
Vol 28 (2) ◽  
pp. 024503
Author(s):  
Mohammed amin Ferdi ◽  
Abdelaaziz Bouziane ◽  
Mourad Djebli
Keyword(s):  
Nitric Oxide ◽  
Electron Impact ◽  
Excited States ◽  
Time Dependent ◽  
Dependent Behavior

Time-dependent behavior of retaining piles during pre-excavation dewatering in multi-layered saturated soils

2021 ◽  
Vol 137 ◽  
pp. 104300
Author(s):  
Yi Chong Cheng ◽  
Ri Hong Zhang ◽  
Kui Hua Wang ◽  
Zhi Yong Ai
Keyword(s):  
Time Dependent ◽  
Saturated Soils ◽  
Dependent Behavior

The flow properties of honey–malt spread

2017 ◽  
Vol 23 (5) ◽  
pp. 415-425 ◽  
Author(s):  
M Dianat ◽  
M Taghizadeh ◽  
F Shahidi ◽  
SMA Razavi
Keyword(s):  
Flow Behavior ◽  
Time Dependent ◽  
Malt Extract ◽  
Barley Malt ◽  
First Order ◽  
Dependent Behavior ◽  
Thixotropic Behaviour ◽  
Order Stress ◽  
Temperature Levels ◽  
Independent Behavior

In this study, the effect of barley malt extract at two brix levels (74 and 79 °Bx) and three ratios of malt extract/honey (65:35, 70:30 and 75:25) on the flow behavior properties of honey–malt spread at three temperature levels (35 ℃, 45 ℃ and 55 ℃) was investigated. Time-dependent behavior data of the spread samples were appropriately fitted to the Weltman, first-order stress decay with a zero stress value and first-order stress decay with a non-zero stress value models. Also, the Power-law, Herschel–Bulkley, Casson and Bingham models were used for curve fitting the time-independent behavior data. Regarding the R2 and root mean square error coefficients, the first-order stress decay with a non-zero stress value and Herschel–Bulkley models were selected as the suitable models to describe the flow behavior of samples. The results for time-dependent properties showed that spread samples exhibit a thixotropic behaviour, as the viscosity for all samples decreased with increase in shearing time at a constant shear rate of 50 s−1.

Time-Dependent Behavior and Fracture of Functionally Graded Thermal Barrier Coatings under Thermal Shock

2005 ◽  
Vol 492-493 ◽  
pp. 379-384 ◽  
Author(s):  
Klod Kokini ◽  
Sudarshan V. Rangaraj
Keyword(s):  
Thermal Shock ◽  
Thermal Barrier Coatings ◽  
Functionally Graded ◽  
Yttria Stabilized Zirconia ◽  
Time Dependent ◽  
Thermal Barrier ◽  
Stabilized Zirconia ◽  
Barrier Coatings ◽  
Dependent Behavior ◽  
Bond Coat Alloy

The thermal fracture and its dependence on time-dependent behavior in functionally graded yttria stabilized zirconia - NiCoCrAlY bond coat alloy thermal barrier coatings was studied. The response of three coating architectures of similar thermal resistance to laser thermal shock tests was considered, experimentally and computationally.

scholarly journals Time Dependent Behavior of Soft Rock and Its Essential Interpretation.

1998 ◽  
pp. 1-10 ◽  
Author(s):  
Toshihisa Adachi ◽  
Fusao Oka ◽  
Hiroshi Soraoka ◽  
Masashi Koike
Keyword(s):  
Soft Rock ◽  
Time Dependent ◽  
Dependent Behavior

Frictional Behavior of Textile Fabrics Part I: Sliding Phenomena of Fabrics on Metallic and Polymeric Solid Surfaces

1997 ◽  
Vol 67 (11) ◽  
pp. 793-802 ◽  
Author(s):  
Luis Virto ◽  
Arun Naik
Keyword(s):  
Sliding Friction ◽  
Solid Material ◽  
Solid Surfaces ◽  
Friction Behavior ◽  
Stick Slip ◽  
Compression Load ◽  
Physical Description ◽  
Frictional Behavior ◽  
Textile Fabrics ◽  
Polymeric Solid

This paper presents experimental results on the sliding of fabrics on metallic and polymeric solid surfaces, showing the influence of the compression load at the solid-fabric interface and the nature of the solid material, and the effect of sliding speed on the sliding friction coefficient. At the same time, a physical description of the sliding phenomenon is given. On the basis of these observations, a theoretical approach is developed to explain the sliding friction behavior of fabrics on solid surfaces. Part II will deal with the waving and stick-slip phenomena, which are evident in the sliding process under certain conditions.

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