Analysis of polymer viscoelastic properties based on compressive creep tests during hot embossing for two-dimensional polyethylene terephthalate nanochannels

2013 ◽  
Vol 54 (10) ◽  
pp. 2398-2406 ◽  
Author(s):  
Zhifu Yin ◽  
E Cheng ◽  
Helin Zou ◽  
Petr Jurčíček
Keyword(s):  
Polyethylene Terephthalate ◽  
Viscoelastic Properties ◽  
Hot Embossing ◽  
Two Dimensional ◽  
Creep Tests ◽  
Compressive Creep

Tensile and Compressive Creep Behavior of IN718 Alloy Manufactured by Selective Laser Melting

2020 ◽  
Vol 986 ◽  
pp. 102-108 ◽  
Author(s):  
Zhen Xu ◽  
Chuan Guo ◽  
Zhen Rong Yu ◽  
Xin Li ◽  
Xiao Gang Hu ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Chemical Potential ◽  
Creep Process ◽  
Tension Stress ◽  
Creep Tests ◽  
Compressive Creep ◽  
Large Size ◽  
Stress Orientation ◽  
Evolution Of Microstructure ◽  
Tension Compression Asymmetry

Tensile and compressive creep behavior of SLMed IN718 alloy under 973K (700°C) were investigated. Crept samples were analyzed by SEM and TEM to expose evolution of microstructure, precipitates and dislocation structure during the creep process. Results show that initial creep rate under compression is higher than under tension for the same creep conditions. Minimum creep rates are approximately the same both in tensile and compressive creep tests. The different creep behaviors may be related to the fact that tension stress promotes precipitations of fine needle-like γ′′ phases, while compression stress promotes precipitations of large size δ phases. The tension-compression asymmetry owns to the increment of chemical potential varying with the stress orientation.

scholarly journals Creep of Ice under Low Stress

1969 ◽  
Vol 8 (52) ◽  
pp. 147-152 ◽  
Author(s):  
Malcolm Mellor ◽  
Richard Testa
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Creep Tests ◽  
Compressive Creep ◽  
Fine Grained ◽  
Polycrystalline Ice ◽  
Viscous Behaviour

Uniaxial compressive creep tests on fine-grained polycrystalline ice indicate that secondary strain-rate is proportional toσ1.8, whereσis applied stress, for the range 0.1 <σ< 0.5 kgf/cm2(10 <σ< 50 kN/m2). On the basis of the present tests, earlier results suggesting linear viscous behaviour at low stress are believed to be invalid.

Alloy Constitution Dependence of Strength and Deformation in Aluminum-Titanium-Vanadium Ternary Alloys Containing Gamma+Beta Dual Phase Microstructures

2010 ◽  
Vol 638-642 ◽  
pp. 350-355
Author(s):  
Tohru Takahashi ◽  
Na Liu ◽  
Yusuke Yazawa ◽  
Takuya Nunome
Keyword(s):  
High Strength ◽  
Beta Phase ◽  
Vanadium Content ◽  
Ternary Alloys ◽  
Dual Phase ◽  
Gamma Phase ◽  
Proof Stress ◽  
Creep Tests ◽  
Compressive Creep ◽  
High Level

Compression and compressive creep behavior was studied on Al-Ti-V ternary alloys containing gamma+beta dual phase microstructures; the gamma phase was based on an L10 face centered tetragonal lattice and the beta phase on a disordered body centered cubic lattice. Yield strength and its temperature dependence have been compared with those in the gamma and/or beta single phase materials. The ternary alloy compositions were located on one assumed conjugate line across the gamma+beta dula phase field: the terminal compositions for the gamma and beta phase constituents were Al51Ti40V9 and Al35Ti20V45, respectively (numbers in atomic %). Three other alloys were prepared that contained different fractions of the constituent gamma and beta phases. The Al47Ti35V18, Al43Ti30V27, and Al39Ti25V36 alloys contained beta phase by about 22, 57, and 76 % in their area fractions. All these alloys showed limited deformability at temperature below 900K. The 0.2% proof stresses of the alloys were described in a similar way as a combination law at the room temperature; the 0.2% proof stress increased from about 500 to 1000 MPa with increasing the vanadium content. The high strength of the alloys containing high level of vanadium retained up to 900K, but the proof stress drastically diminished as the temperature was raised above 900K. Under compressive creep tests performed at temperatures ranging from 1100 to 1200 K, the minimum creep rates were smaller in the alloys containing less vanadium, and this could be ascribed to the fact that the beta phase was much softer than the gamma phase at higher temperatures than about 1000K.

Tensile and Compressive Creep Behavior of Coarse-Grained Mg-Al-Sr Castings

2007 ◽  
Vol 546-549 ◽  
pp. 171-174 ◽  
Author(s):  
Peng Zhao ◽  
Qu Dong Wang ◽  
Chun Quan Zhai ◽  
Wen Jiang Ding
Keyword(s):  
Creep Rate ◽  
Coarse Grained ◽  
Stress Range ◽  
Creep Tests ◽  
Gravity Casting ◽  
Creep Properties ◽  
Compressive Creep ◽  
Creep Mechanisms ◽  
Asymmetric Behavior ◽  
Tension And Compression

Tensile and compressive creep properties of Mg-5wt.%Al-1wt.%Sr alloy produced by gravity casting were investigated in this paper. Creep tests were carried out in the temperature range from 125 °C to 200 °C and stress range from 35 to 85MPa. The second creep rate in tension is significant different from that in compression, indicating that coarse-grained Mg-Al-Sr alloy exhibits tension/compression asymmetric behavior. Moreover, the activation energies and stress exponent in tension and compression are not the same, which suggest that creep mechanisms in tension and compression are different.

Viscoelastic Properties of Semi-Crystalline Thermoplastic Polymers: Dynamic Analysis and Creep

2012 ◽  
Vol 188 ◽  
pp. 211-218 ◽  
Author(s):  
Dan Andrei Serban ◽  
Henry Hanson ◽  
Liviu Marşavina ◽  
Vadim V. Silberschmidt
Keyword(s):  
Viscoelastic Properties ◽  
Polymeric Materials ◽  
Mechanical Analysis ◽  
External Loading ◽  
Thermoplastic Polymer ◽  
Elastic Solids ◽  
Short Term ◽  
Creep Tests ◽  
And Storage

When subjected to external loading, polymeric materials behave in a manner intermediate between elastic solids and viscous fluids. Their mechanical properties depend on a material’s viscous flow, which, in turn, is influenced by (i) temperature, with its different magnitudes determining a ductile or brittle behaviour and (ii) time, through the effect of a deformation rate and long-term relaxation. Short-term viscoelastic properties (loss and storage moduli) of a studied semi-crystalline thermoplastic polymer were obtained using Dynamic Mechanical Analysis, while its long-term viscoelastic properties (compliances) were determined using creep tests.

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