scholarly journals The response of Opalinus Clay when exposed to cyclic relative humidity variations

2016 ◽  
Author(s):  
Katrin M. Wild ◽  
Patric Walter ◽  
Florian Amann
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Environmental Changes ◽  
Opalinus Clay ◽  
Brazilian Tensile Strength ◽  
Internal Damage ◽  
Direction Parallel ◽  
Clay Shale ◽  
Retention Characteristic ◽  
Bedding Planes

Abstract. Clay shale specimens were exposed to cyclic relative humidity variations to investigate the response of the material to natural environmental changes. Opalinus Clay, a clay shale chosen as host rock for nuclear waste disposal in Switzerland, was utilized. The specimens were exposed to stepwise relative humidity cycles where they were alternately allowed to equilibrate at 66 and 93 % relative humidity. Principal strains were monitored throughout the experiments using strain gauges. After each relative humidity cycle, Brazilian tensile strength tests were performed to identify possible changes in tensile strength due to environmental degradation. Results showed that Opalinus Clay follows a cyclic swelling-shrinkage behaviour with irreversible expansion limited to the direction normal to bedding, suggesting that internal damage is restricted along the bedding planes. The Brazilian tensile strength in direction parallel and normal to bedding as well as the water retention characteristic remained unaffected by the RH variations.

scholarly journals The response of Opalinus Clay when exposed to cyclic relative humidity variations

Solid Earth ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 351-360 ◽  
Author(s):  
Katrin M. Wild ◽  
Patric Walter ◽  
Florian Amann
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Environmental Changes ◽  
Opalinus Clay ◽  
Brazilian Tensile Strength ◽  
Internal Damage ◽  
Direction Parallel ◽  
Clay Shale ◽  
Retention Characteristic ◽  
Bedding Planes

Abstract. Clay shale specimens were exposed to cyclic relative humidity (RH) variations to investigate the response of the material to natural environmental changes. Opalinus Clay, a clay shale chosen as host rock for nuclear waste disposal in Switzerland, was utilized. The specimens were exposed to stepwise relative humidity cycles in which they were alternately allowed to equilibrate at 66 and 93 % relative humidity. Principal strains were monitored throughout the experiments using strain gauges. After each relative humidity cycle, Brazilian tensile strength tests were performed to identify possible changes in tensile strength due to environmental degradation.Results showed that Opalinus Clay follows a cyclic swelling–shrinkage behaviour with irreversible expansion limited to the direction normal to bedding, suggesting that internal damage is restricted along the bedding planes. The Brazilian tensile strength in direction parallel and normal to bedding as well as the water retention characteristic remained unaffected by the RH variations.

scholarly journals AN INVESTIGATION ON THE EFFECTS OF MICRO-PARAMETERS ON THE STRENGTH PROPERTIES OF ROCK

2021 ◽  
Vol 36 (1) ◽  
pp. 111-119
Author(s):  
Behzad Jafari Mohammadabadi ◽  
Kourosh Shahriar ◽  
Hossein Jalalifar ◽  
Kaveh Ahangari
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Friction Coefficient ◽  
Critical Stress ◽  
Friction Angle ◽  
Strength Properties ◽  
Brazilian Tensile Strength ◽  
The Relationship

Rocks are formed from particles and the interaction between those particles controls the behaviour of a rock’s mechanical properties. Since it is very important to conduct extensive studies about the relationship between the micro-parameters and macro-parameters of rock, this paper investigates the effects of some micro-parameters on strength properties and the behaviour of cracks in rock. This is carried out by using numerical simulation of an extensive series of Uniaxial Compressive Strength (UCS) and Brazilian Tensile Strength (BTS) tests. The micro-parameters included the particles’ contact modulus, the contact stiff ness ratio, bond cohesion, bond tensile strength, the friction coefficient and the friction angle, and the mechanical properties of chromite rock have been considered as base values of the investigation. Based on the obtained results, it was found that the most important micro-parameters on the behaviour of rock in the compressive state are bond cohesion, bond tensile strength, and the friction coefficient. Also, the bond tensile strength showed the largest effect under tensile conditions. The micro-parameter of bond tensile strength increased the rock tensile strength (up to 5 times), minimized destructive cracks and increased the corresponding strain (almost 2.5 times) during critical stress.

Research on the Influence of Salt Fog Corrosion Behavior of 6005A Aluminum Alloy Welded Joints by Environment Humidity

2013 ◽  
Vol 662 ◽  
pp. 251-257
Author(s):  
Ning Xia ◽  
Zhi Min Zhu ◽  
Hui Chen
Keyword(s):  
Weight Loss ◽  
Tensile Strength ◽  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Relative Humidity ◽  
Corrosion Rate ◽  
Environmental Humidity ◽  
Welding Joints ◽  
Salt Fog Corrosion ◽  
Salt Fog

6005A aluminum alloys were welded at different relative humidity conditions. The effects of relative humidity on the salt fog corrosion of the welding joints were researched. The results showed that the weight loss of the joints after 14 days corrosion was higher than that corroded after 7days, but the corrosion rate was lower. The corrosion rate first increased then declined with the increase of environmental humidity for the joints corroded for 7days. However, when the environmental humidity was 80%, corrosion rate achieved the maximum, when environment humidity was 70%, corrosion rate was the lowest. After corroded for 14 days, corrosion rate was the maximum when the environmental humidity was 50%, and it was the lowest when the environmental humidity was 90%. The tensile strength declined obviously after corrosion.

Environmental Effects on the Mechanical Behavior of Covetic Aluminum MEMS Components

2017 ◽  
Author(s):  
Seyed M. Allameh ◽  
Jennifer Wardlow
Keyword(s):  
Tensile Strength ◽  
Relative Humidity ◽  
Cross Section ◽  
Environmental Effects ◽  
Tensile Testing ◽  
Fatigue Loading ◽  
Positive Pressure ◽  
Work Piece ◽  
Microtensile Testing ◽  
Dog Bone

Covetic aluminum has been researched for its mechanical properties. It has been credited with higher strength in tensile and fatigue loading [1,2]. Modest changes in temperature during tensile testing of covetic aluminum causes significant changes in the ductility and tensile strength. Increasing the temperature from 15 °C to 44 °C causes a decrease in the tensile strength down to 63.8% but an increase in the ductility up to 117% [3]. To further study the environmental effects, microtensile testing was carried out in an environmentally-controlled chamber using a hybrid microtester at high and low relative humidity. MEMS-scale dog-bone shaped specimens with a cross section of 200 × 250 microns were machined from bulk covetic aluminum using a CNC for milling their contours and a ram-type EDM for detaching them from the work piece. The chamber was purged with gases low or high in moisture maintaining a positive pressure. An Omega sensor-controller unit was used to regulate the temperature and relative humidity of the chamber. The results of the tests show a reduction of ductility at high relative humidity. The implications of the results are discussed in relation to the reliability of MEMS structures.

Hydro-mechanical behaviour of shallow Opalinus Clay shale

2019 ◽  
Vol 251 ◽  
pp. 214-227 ◽  
Author(s):  
Eleonora Crisci ◽  
Alessio Ferrari ◽  
Silvio B. Giger ◽  
Lyesse Laloui
Keyword(s):  
Mechanical Behaviour ◽  
Opalinus Clay ◽  
Clay Shale
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