Contribution of Primary Creep in Modeling the Mechanical Behavior of Polycrystalline Ice

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
G. Aryanpour ◽  
M. Farzaneh
Keyword(s):  
Mechanical Behavior ◽  
Primary Creep ◽  
Experimental Results ◽  
Secondary Creep ◽  
Inelastic Behavior ◽  
Viscoplastic Deformation ◽  
Polycrystalline Ice

In most of the models proposed for deformation of ice, in addition to instantaneous elastic and viscoelastic parts, a viscoplastic part is also considered. An expression used for material secondary creep is usually employed to describe the viscoplastic component. In this study, however, another viscoplastic deformation of primary creep type is also considered in addition to the secondary creep. Therefore the permanent contribution of deformation is suggested to consist of primary and secondary creep parts. The existence of the primary creep contribution is investigated and characterized by using experimental results reported in the literature. The identified primary creep contribution is then validated by other available experimental results. Finally, the significance of primary creep in the inelastic behavior will be discussed.

Creep rates of spray ice

1990 ◽  
Vol 27 (2) ◽  
pp. 185-194 ◽  
Author(s):  
D. Shields ◽  
L. Domaschuk ◽  
E. Funegard
Keyword(s):  
Power Law ◽  
Constant Pressure ◽  
Creep Behaviour ◽  
Primary Creep ◽  
Control Device ◽  
Petroleum Exploration ◽  
Secondary Creep ◽  
Creep Tests ◽  
Pressure Tests ◽  
Polycrystalline Ice

Mars Island, a man-made spray ice island, was constructed in January and February 1986, and was used as a drill platform for petroleum exploration in the Alaskan Beaufort Sea. A series of pressuremeter creep tests was run in the spray ice of Mars Island in March 1986. Individual constant-pressure tests lasted up to 5 days.It is possible to compare the creep behaviour of the spray ice as interpreted from the pressuremeter tests with the creep behaviour interpreted from the island settlement records. These comparisons are made for both primary and secondary creep on the basis of conventional power law theory. The following points are of particular interest: (1) The primary creep data can be characterized using a simple power law. The exponent of time for spray ice is similar to that for solid polycrystalline ice. The exponent of stress is different for the two kinds of ice. (2) Pressuremeter tests gave secondary creep information that correlates well with the steady-rate settlement of the island. (3) Research into the possible range of primary creep parameters for spray ice is required, given that primary creep accounted for a large portion of the settlement of Mars Island. In particular, the effect of ice density on creep rates mast be resolved. (4) The pressuremeter is potentially an excellent design control device during the manufacture of future spray ice islands. The results of constant-pressure tests of 1–2 days duration could be used to check the design assumptions pertaining to the expected consolidation of the ice mass with time. Key words: spray ice, creep, artificial islands, pressuremeter, settlement.

scholarly journals Creep Damage Repair of a Nickel-Based Single Crystal Superalloy Based on Heat Treatment

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 623
Author(s):  
Xiaoyan Wang ◽  
Meng Li ◽  
Yuansheng Wang ◽  
Chengjiang Zhang ◽  
Zhixun Wen
Keyword(s):  
Heat Treatment ◽  
Single Crystal ◽  
Creep Damage ◽  
Primary Creep ◽  
Single Crystal Superalloy ◽  
Secondary Creep ◽  
Creep Life ◽  
Phase Coarsening ◽  
Damage Repair ◽  
Creep Time

Taking nickel-based single crystal superalloy DD6 as the research object, different degrees of creep damage were prefabricated by creep interruption tests, and then the creep damage was repaired by the restoration heat treatment system of solid solution heat treatment and two-stage aging heat treatment. The results show that with the creep time increasing, the alloy underwent microstructure evolution including γ′ phase coarsening, N-type rafting and de-rafting. After the restoration heat treatment, the coarse rafted γ′ phase of creep damaged specimens dissolved, precipitated, grew up, and became cubic again. Except for the specimens with creep interruption of 100 h, the γ′ phase can basically achieve the same arrangement as the γ′ phase of the original sample. The comparison of the secondary creep test shows that the steady-state creep stage of the test piece after the restoration heat treatment is relatively increased, and the total creep life can reach the same level as the primary creep life. The high temperature creep properties of the tested alloy are basically recovered, and the restoration heat treatment effect is good.

Constitutive modeling for the mechanical behavior of rubber with filler particles

2021 ◽  
Author(s):  
Sankalp Gour ◽  
Deepu Kumar Singh ◽  
Deepak Kumar ◽  
Vinod Yadav
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Mechanical Behavior ◽  
Experimental Observation ◽  
Continuum Mechanics ◽  
Constitutive Modeling ◽  
Carbon Nanoparticles ◽  
Material Behavior ◽  
Experimental Results ◽  
Filler Particles

Abstract The present study deals with the constitutive modeling for the mechanical behavior of rubber with filler particles. An analytical model is developed to predict the mechanical properties of rubber with added filler particles based on experimental observation. To develop the same, a continuum mechanics-based hyperelasticity theory is utilized. The model is validated with the experimental results of the chloroprene and nitrile butadiene rubbers filled with different volume fractions of carbon black and carbon nanoparticles, respectively. The findings of the model agree well with the experimental results. In general, the developed model will be helpful to the materialist community working in characterizing the material behavior of tires and other rubber-like materials.

scholarly journals Durability analysis of underground structures based on various creep models of the enclosing salt rock massif

2020 ◽  
Vol 201 ◽  
pp. 01007
Author(s):  
Mikhail Zhuravkov ◽  
Sergey Hvesenya ◽  
Siarhei Lapatsin
Keyword(s):  
Underground Structure ◽  
Primary Creep ◽  
Rock Massif ◽  
Initial Time ◽  
Creep Process ◽  
Secondary Creep ◽  
Salt Rock ◽  
Mine Shaft ◽  
Durability Analysis ◽  
Creep Models

The results of the durability analysis of a complex underground structure and surrounding multilayered rock massif are presented. The research is conducted based on an applied stress-strain state problem for a salt rock massif in the vicinity of an underground cavity of a large cross-section which is in conjunction with a mine shaft. The main aim of the research is to perform a comparative analysis of various mathematical models of the creep process. The problem is solved using finite element method to achieve this goal. Regularity in the development of deformation processes of the enclosing rock massif is established as a result of the study. According to this regularity, both primary creep and primary-secondary creep models show that the main increase of creep deformations occurs during a short initial time period after which creep strain rate decreases sharply.

Efficiency of Bio-Sourced Composites in Confining Recycled Aggregates Concrete

2022 ◽  
Author(s):  
Elhem Ghorbel ◽  
Mariem Limaiem
Keyword(s):  
Mechanical Behavior ◽  
Analytical Modeling ◽  
Mechanical Characteristics ◽  
Epoxy Polymer ◽  
Experimental Results ◽  
Confined Concrete ◽  
Recycled Aggregates ◽  
Demolition Waste ◽  
Traditional System ◽  
Flax Fibers

This research investigates the efficiency of using Flax Fibers reinforced bio-sourced polymer by comparison to traditional system based on Carbone Fiber Reinforced Epoxy Polymer in order to confine recycled aggregates concrete. Four concrete formulations have been formulated by incorporating recycled aggregates from demolition waste (0%, 30%, 50% and 100%). An air-entraining agent was added to the formulations to achieve the level of 4% occluded air. The main objective is to discuss and to evaluate the effectiveness of confining them using bio-sourced composite by comparison to traditional ones. To hit this target, the developed approaches are both experimental and analytical. The first part is experimental and aimed to characterize the mechanical behavior of the materials: the composites used in the confining process the unconfined concrete (effect of incorporating recycled aggregates on the overall mechanical characteristics). We establish that bio-sourced composites are efficient in strengthening recycled aggregates concrete especially if they are air-entrained. The second part of this work is dedicated to analytical modeling of mechanical behavior of confined concrete with composite under compression based on Mander’s model. The input parameters of the model were modified to consider the rate of recycled aggregates incorporation. Comparison between experimental results and the modified Mandel’s Model is satisfactory.

Modified State Surface Approach to Study Unsaturated Soil Hysteresis Behavior

2020 ◽  
Vol 2674 (10) ◽  
pp. 484-498
Author(s):  
Beshoy Riad ◽  
Xiong Zhang
Keyword(s):  
Mechanical Behavior ◽  
Unsaturated Soils ◽  
Construction Material ◽  
Constitutive Models ◽  
Experimental Results ◽  
Special Focus ◽  
Surface Approach ◽  
Hysteresis Behavior ◽  
Mechanical Hysteresis ◽  
Hydraulic Hysteresis

Unsaturated soils are often used as a construction material in transportation infrastructures. In this situation, unsaturated soils are subjected to cyclic mechanical loading from traffic loads or wetting-drying cycles in seasonal climatic conditions. While mechanical hysteresis is a common feature of soils in general, hydraulic hysteresis is associated with unsaturated soils. Although several constitutive models for unsaturated soils have been proposed, the mechanical and hydraulic hysteresis behavior of unsaturated soils has been little studied. A modified state surface approach (MSSA) was first proposed for investigating the mechanical behavior of unsaturated soils. It was then extended to study the coupled hydro-mechanical behavior of unsaturated soils with a special focus on the consistency between different soil phases. However, hydraulic and mechanical hysteresis were neglected in MSSA formulations. In this paper, based on evidence from experimental results, the MSSA is extended further to study the coupled hydro-mechanical hysteresis behavior of unsaturated soils. The extended MSSA can reproduce several forms of mechanical and hydraulic behavior observed in experimental results that cannot be represented by existing constitutive models. To demonstrate the capabilities of the extended MSSA, typical behaviors are simulated and compared, qualitatively, with the characteristic trends of the behavior of unsaturated soils. Experimental results from the literature are then used to evaluate the model to predict, quantitatively, the observed behaviors. The agreement between measured and predicted results is considered satisfactory and confirms the possibility of the proposed approach to reproduce the hysteresis behavior of unsaturated soils.

scholarly journals Experimental results and constitutive model of the mechanical behavior of Ti6Al4V alloy at high temperature

2019 ◽  
Vol 41 ◽  
pp. 723-730
Author(s):  
Jorge Ayllón Perez ◽  
Valentín Miguel Eguía ◽  
Juana Coello Sobrino ◽  
Alberto Martínez Martínez
Keyword(s):  
High Temperature ◽  
Constitutive Model ◽  
Mechanical Behavior ◽  
Ti6al4v Alloy ◽  
Experimental Results

High-Temperature Mechanical Behavior of B2 Type IrAl Doped With Ni

1996 ◽  
Vol 460 ◽  
Author(s):  
A. Chiba ◽  
T. Ono ◽  
X. G. Li ◽  
S. Takahashi
Keyword(s):  
Steady State ◽  
Mechanical Behavior ◽  
Constant Velocity ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Constant Load ◽  
Secondary Creep ◽  
Compression Tests ◽  
Order Of Magnitude ◽  
Multi Phase

ABSTRACTConstant-velocity and constant-load compression tests have been conducted to examine the mechanical behavior of polycrystalline IrAl and Ir1-xNixAl at ambient and elevated temperatures. Although IrAl exhibits brittle fracture before or immediately after yielding below 1073K, steady-state deformation takes place at temperatures higher than 1273K. Ductility of Ir1-xNixAl is improved with increasing x. On the contrary, strength decreases with increasing x. IrAl exhibits the 0.2% flow stress of 1200MPa at 1073K and 350MPa at 1473K, about an order of magnitude higher than NiAl. Secondary creep of IrAl and Ir0.2Ni0.8Al(i.e., modified NiAl) exhibits class II and class I behavior respectively. Creep strength of binary IrAl and modified NiAl with Ir is about a magnitude of 4 higher than that of single-phase and multi-phase NiAl at a given applied stress.

DISLOCATION STRUCTURES IN COPPER SINGLE CRYSTALS DEFORMED IN HIGH TEMPERATURE CREEP

1967 ◽  
Vol 45 (2) ◽  
pp. 1213-1220 ◽  
Author(s):  
V. P. Gupta ◽  
P. R. Strutt
Keyword(s):  
Strain Rate ◽  
Single Crystals ◽  
Initial Strain Rate ◽  
Primary Creep ◽  
Secondary Creep ◽  
Etch Pit ◽  
Structure Changes ◽  
Initial Stage ◽  
Copper Single Crystals ◽  
Distribution Of Dislocations

The etch-pit technique has been used to study dislocations and substructures in copper single crystals deformed in primary, and into secondary creep at 550 °C at a CRSS of 250 g.mm−2. Etch-pit structures in crept specimens were observed parallel to the primary (111) plane and also the (111) plane to reveal "forest dislocations" and primary and other dislocations. In the initial stage of primary creep, the dislocations formed well-defined cells. Subboundaries began to form later on in primary creep. When a steady-state creep ensued, a well-developed subboundary structure was evident, with a random distribution of dislocations within the subgrains. The mean subgrain diameter was approximately twice that of the original cells and the dislocation density decreased by a factor of 2 during primary creep. Since the general form of the dislocation structure changes during primary creep, it is concluded that the decreasing strain rate cannot be ascribed to any one particular mechanism. However, the high initial strain rate probably results from the escape of dislocations from the cell walls in the initial type of structure.

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