scholarly journals Constructing a transformation curve of the age resistance coefficient

Author(s):  
T A Matseevich ◽  
E V Korolev ◽  
A A Askadsky
INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
A. V. Matseevich ◽  
◽  
A. A. Askadskii ◽  

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).


Econometrica ◽  
1966 ◽  
Vol 34 (3) ◽  
pp. 686 ◽  
Author(s):  
Harry G. Johnson
Keyword(s):  

2015 ◽  
Vol 26 (01) ◽  
pp. 59-110 ◽  
Author(s):  
Claude Bardos ◽  
Denis Grebenkov ◽  
Anna Rozanova-Pierrat

We consider a heat problem with discontinuous diffusion coefficients and discontinuous transmission boundary conditions with a resistance coefficient. For all bounded (ϵ, δ)-domains Ω ⊂ ℝn with a d-set boundary (for instance, a self-similar fractal), we find the first term of the small-time asymptotic expansion of the heat content in the complement of Ω, and also the second-order term in the case of a regular boundary. The asymptotic expansion is different for the cases of finite and infinite resistance of the boundary. The derived formulas relate the heat content to the volume of the interior Minkowski sausage and present a mathematical justification to the de Gennes' approach. The accuracy of the analytical results is illustrated by solving the heat problem on prefractal domains by a finite elements method.


2011 ◽  
Vol 243-249 ◽  
pp. 3659-3662
Author(s):  
Hai Ying Zhou ◽  
Li Xin Li ◽  
Ting Guo Chen

Based on the segmental joint tests, it was found that the practical range of joint flexural rigidity was in range of 8500-29000kN•m/rad. A simplified method for determining the stiffness reduction factor of tunnel lining() was proposed using results from the segmental joint tests in which some parameters were obtained by calibration against a 3D Numerical analysis. The influence of joint flexural rigidity, soil resistance coefficient, thickness of tunnel lining and tunnel calculation radius on the stiffness reduction factor of tunnel lining was examined. The stiffness reduction factor can be simply expressed as a function of joint flexural rigidity ratio, soil resistance coefficient, thickness of tunnel lining and tunnel calculation radius for the typical tunnel lining.


2002 ◽  
Vol 124 (2) ◽  
pp. 492-499 ◽  
Author(s):  
Michael P. Schultz

An experimental investigation has been carried out to document and relate the frictional resistance and roughness texture of painted surfaces smoothed by sanding. Hydrodynamic tests were carried out in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106−5.5×106 based on the plate length and freestream velocity. Results indicate an increase in frictional resistance coefficient CF of up to 7.3% for an unsanded, as-sprayed paint surface compared to a sanded, polished surface. Significant increases in CF were also noted on surfaces sanded with sandpaper as fine as 600-grit as compared to the polished surface. The results show that, for the present surfaces, the centerline average height Ra is sufficient to explain a large majority of the variance in the roughness function ΔU+ in this Reynolds number range.


2021 ◽  
pp. 002199832110370
Author(s):  
Chia-Fang Lee ◽  
Chin-Wen Chen ◽  
Fu-Sheng Chuang ◽  
Syang-Peng Rwei

Multi-wall carbon nanotubes (MWCNTs) at 0.5 wt% to 2 wt% proportions were added to thermoplastic polyurethane (TPU) synthesized with polycarbonatediol (PCDL), 4,4’-methylene diphenyl diisocyanate (MDI), and 1,3-butanediol(1,3-BDO). To formulate a new TPU-MWCNT nanocomposite, the composite was melt-blended with a twin-screw extruder. To ensure the even dispersion of MWCNTs, dispersant (ethylene acrylic ester terpolymer; Lotader AX8900) of equal weight proportion to the added MWCNTs was also added during the blending process. Studies on the mechanical and thermal properties, and melt flow experiments and phase analysis of TPU-MWCNT nanocomposites, these nanocomposites exhibit higher tensile strength and elongation at break than neat TPU. TPU-MWCNT nanocomposites with higher MWCNT content possess higher glass-transition temperature (Tg), a lower melt index, and greater hardness. Relative to neat TPU, TPU-MWCNT nanocomposites exhibit favorable mechanical properties. By adding MWCNTs, the tensile strength of the nanocomposites increased from 7.59 MPa to 21.52 MPa, and Shore A hardness increased from 65 to 81. Additionally, TPU-MWCNT nanocomposites with MWCNTs had lower resistance coefficients; the resistance coefficient decreased from 4.97 × 1011 Ω/sq to 2.53 × 104 Ω/sq after adding MWCNTs, indicating a conductive polymer material. Finally, the internal structure of the TPU-MWCNT nanocomposites was examined under transmission electron microscopy. When 1.5 wt% or 2 wt% of MWCNTs and dispersant were added to TPU, the MWCNTs were evenly dispersed, with increased electrical conductivity and mechanical properties. The new material is applicable in the electronics industry as a conductive polymer with high stiffness.


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