scholarly journals An Experimental Study on Characteristics of Impact Compression of Freeze-Thawed Granite Samples Under Four Different States Considering Moisture Content and Temperature Difference

2021 ◽  
Author(s):  
Chunyang Zhang ◽  
Bo Ke ◽  
Chuanju Liu ◽  
Linmin Ding ◽  
Yixian Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Impact Strength ◽  
Influence Factor ◽  
Dynamic Elastic Modulus ◽  
Rock Masses ◽  
Impact Compression ◽  
Freeze Thaw ◽  
The Impact ◽  
Granite Samples

Abstract The mechanics of rock masses in cold regions have attracted the attention of researchers from all over the world, and the concern here is that the mechanical properties of rock masses are inevitably weakened under freeze-thaw cycles. In this paper, firstly, granite samples were subjected to different freeze-thaw cycles, after that, we dealt with the freeze-thawed samples considering four different states, such as saturated and frozen states, saturated and normal temperature states, dry and frozen states as well as dry and normal temperature states. The impact compression test was carried out by using the Split Hopkinson Pressure Bar (SHPB) device. Results show that the impact strength of granite samples deteriorates with the increase of freeze-thaw cycles in the same state, for samples in different states, although the number of freeze-thaw cycles is equal, the degree of deterioration of the impact strength is different. For freeze-thawed granite samples in the same state, the dynamic elastic modulus decreases with the increase of freeze-thaw cycles, and its degree of decrease is different for different states. Under the same freeze-thaw cycles, the deterioration of mechanical properties of granite samples is different in four different weather states, for example, the dynamic elastic modulus from large to small is generally as follows: saturated and frozen states, saturated and normal temperature states, dry and frozen states as well as dry and normal temperature states. Finally, the freeze-thaw influence factor is proposed to describe the damage of granite samples. All in all, it can be concluded that water and low temperature strengthen the influence of freeze-thaw cycles on the dynamic mechanical properties of granite samples.

Effects of microcrystalline cellulose on the mechanical properties of low-density polyethylene composites

2018 ◽  
Vol 32 (3) ◽  
pp. 297-311 ◽  
Author(s):  
Yousef Ahmad Mubarak ◽  
Raghda Talal Abdulsamad
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Impact Strength ◽  
Tensile Properties ◽  
Microcrystalline Cellulose ◽  
Weight Fraction ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Ldpe Composites ◽  
The Impact

This work was intended to provide an understanding of the effect of microcrystalline cellulose (MCC) on the mechanical properties of low-density polyethylene (LDPE). The impact resistance and the tensile properties of low-density LDPE/MCC composites were investigated. The weight fraction of MCC was varied at (0, 0.5, 1, 2.5, 5, 10, 20, and 30 wt%). The obtained blends were then used to prepare the required tensile and impact testing samples by hot compression molding technique. It has been found that MCC has a strong influence on the mechanical properties of LDPE. At a low MCC weight fraction, there was a little improvement in the ultimate strength, fracture stress, and elongation at break, but at a high MCC weight fraction, the tensile properties were deteriorated and reduced significantly. The addition of 1 wt% MCC to LDPE enhanced the mentioned properties by 10, 25, and 6%, respectively. While at 30 wt% MCC, these properties were lowered by 36, 25, and 96%. The elastic modulus of LDPE composites was improved on all MCC weight fractions used in the study, at 20 wt% MCC, an increase in the elastic modulus by 12 folds was achieved. On the other hand and compared with the impact strength of pure LDPE, the addition of MCC particles enhanced the impact strength, the highest value obtained was for LDPE composites filled with 10 wt% MCC where the impact strength enhanced by two folds.

scholarly journals Experimental Study on the Mechanical Properties of Sandstone under the Action of Chemical Erosion and Freeze-Thaw Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lizhuang Cui ◽  
Nan Qin ◽  
Shuai Wang ◽  
Xuezhi Feng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Triaxial Compression ◽  
Rock Properties ◽  
Chemical Solution ◽  
Compression Tests ◽  
Chemical Erosion ◽  
Freeze Thaw ◽  
The Impact

In order to study the mechanical properties of sandstone under the coupling action of chemical erosion and freeze-thaw cycles, the fine-grained yellow sandstone in a mining area in Zigong, China, is collected as the research object. The changes in mechanical properties of yellow sandstone under the coupling action of chemical solution erosion and freeze-thaw cycles are analyzed based on uniaxial compression tests (UCTs) and triaxial compression tests (TCTs). The results show that, with the increase in freeze-thaw cycles, the compressive strength, elastic modulus, and cohesion of the sandstone samples decrease with varying degrees. Under constant freeze-thaw cycles, the most serious mechanical properties of degradation are observed in acidic solution, followed by alkaline solution and neutral solution. Under different confining pressures, the compressive strength and elastic modulus of the sandstone samples decrease exponentially with the increase in freeze-thaw cycles. Under the action of the chemical solution erosion and freeze-thaw cycles, the internal friction angle fluctuates around 30°. For the cohesion degradation, 35.4%, 29.3%, and 27.2% degradation are observed under acidic, alkaline, and neutral solutions. Nuclear magnetic resonance imaging shows that the chemical erosion and freeze-thaw cycles both promote the degradation of rock properties from surface to interior; after 45 freeze-thaw cycles, the mechanical properties drop sharply. To properly design rock tunneling support and long-term protection in the cold region, the impact of both freeze-thaw cycles and chemical erosion should be considered.

The dependence of the annealed cold-packed hearth mass elasticity from the degree of its compaction

2020 ◽  
pp. 35-38
Author(s):  
M. Y. Babkin ◽  
S. I. Borovik ◽  
A. I. Soldatov
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mass Density ◽  
Dynamic Elastic Modulus ◽  
The Impact

The impact of the cold-packed hearth mass density on the annealed mass dynamic elastic modulus is investigated. It is shown that the analysis of the elastic modulus curves allows to determine the area of the hearth mass optimal compaction. In this area, the annealed hearth mass has a level of mechanical properties comparable to hearth blocks.

The influence of the 3D-printing technology on the physical and mechanical properties of polyphenylene sulfone

2018 ◽  
Vol 24 (7) ◽  
pp. 1124-1130 ◽  
Author(s):  
Azamat Ladinovich Slonov ◽  
Azamat Askerovich Khashirov ◽  
Azamat Aslanovich Zhansitov ◽  
Elena Viktorovna Rzhevskaya ◽  
Svetlana Yuryevna Khashirova
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
3D Printing ◽  
Impact Strength ◽  
Orientation Angle ◽  
Physical And Mechanical Properties ◽  
Air Gap ◽  
Content Type ◽  
Fused Deposition ◽  
The Impact

Purpose This paper aims to examine the impact of three-dimensional (3D) printing technological modes (using fused deposition modelling [FDM]) on physical and mechanical properties of samples from polyphenylenesulfone. Design/methodology/approach For this study, the standard test samples were printed using the FDM method at different filament orientation angles, the gaps between them and a different width. The basic physical and mechanical properties, such as the strength, the elastic modulus and the impact strength, were studied. Findings The authors found that the basic mechanical properties strongly depend on the printing settings. In particular, the elastic modulus generally depends on the air gap between rasters, and it is practically independent of the filament orientation angle. In contrast, the impact strength depends on the orientation and the degree of adhesion between filaments: the highest values are reached at the longitudinal orientation of rasters in the sample (0°) and the minimum value of the air gap (−0.025 mm). However, in selecting the optimal mode of 3D printing, it is necessary to take into account the specific geometry of the printing products and the direction of the stress that it will experience. Originality/value The paper presents the results of the investigation of the influence of FDM printing modes on the mechanical properties of samples from polyphenylenesulfone, including impact strength. The authors studied the mechanisms of the destruction under impact loading and revealed the optimal printing settings for making samples with properties which are not inferior to the injection molded samples.

The Effect of Freeze-Thaw Cycles on Mechanical Properties of Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 3429-3432 ◽  
Author(s):  
Wa Li Song ◽  
Xue Fang Li ◽  
Ke Fei Ma
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Service Life ◽  
Frost Resistance ◽  
Loss Rate ◽  
Experiment Data ◽  
Freeze Thaw ◽  
Damage Degree ◽  
Northern Areas ◽  
The Impact

Freeze-thaw cycles have the impact on mechanical properties of the concrete in northern areas of China. In this paper, on the basis of the damage degree of freeze-thaw cycles and experiment data, for C30~ C50 concrete after freeze-thaw cycles, the loss rate of relative dynamic elastic modulus and the relation between compressive stress-strain are analyzed. Compounding good frost resistance of concrete is one of important measures to improve durability of concrete, and degradation patterns of mechanical properties are found. This study may serve as prediction of the service life of concrete in cold regions.

A novel recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) thermoplastic blend

2021 ◽  
pp. 147776062110010
Author(s):  
Zahid Iqbal Khan ◽  
Zurina Binti Mohamad ◽  
Abdul Razak Bin Rahmat ◽  
Unsia Habib ◽  
Nur Amira Sahirah Binti Abdullah
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Flexural Strength ◽  
Polyethylene Terephthalate ◽  
Practical Implication ◽  
Polyamide 11 ◽  
Recycled Polyethylene ◽  
Twin Screw ◽  
Electron Microscopy Analysis ◽  
The Impact

This work explores a novel blend of recycled polyethylene terephthalate/polyamide 11 (rPET/PA11). The blend of rPET/PA11 was introduced to enhance the mechanical properties of rPET at various ratios. The work’s main advantage was to utilize rPET in thermoplastic form for various applications. Three different ratios, i.e. 10, 20 and 30 wt.% of PA11 blend samples, were prepared using a twin-screw extruder and injection moulding machine. The mechanical properties were examined in terms of tensile, flexural and impact strength. The tensile strength of rPET was improved more than 50%, while the increase in tensile strain was observed 42.5% with the addition of 20 wt.% of PA11. The improved properties of the blend were also confirmed by the flexural strength of the blends. The flexural strength was increased from 27.9 MPa to 48 MPa with the addition of 30 wt.% PA11. The flexural strain of rPET was found to be 1.1%. However, with the addition of 10, 20 and 30 wt.% of PA11, the flexural strain was noticed as 1.7, 2.1, and 3.9% respectively. The impact strength of rPET/PA11 at 20 wt.% PA11 was upsurged from 110.53 to 147.12 J/m. Scanning electron microscopy analysis revealed a dispersed PA11 domain in a continuous rPET matrix morphology of the blends. This work practical implication would lead to utilization of rPET in automobile, packaging, and various industries.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

Effect of Wood Filler Concentration on Physical and Mechanical Properties of PLA-Based Composites

2021 ◽  
Vol 887 ◽  
pp. 110-115
Author(s):  
G.A. Sabirova ◽  
R.R. Safin ◽  
N.R. Galyavetdinov
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Composite Materials ◽  
Impact Strength ◽  
Wood Flour ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Filler Concentration ◽  
High Concentration

This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

scholarly journals Effect of Cold Drawing on Mechanical Properties of Biodegradable Fibers

2017 ◽  
Vol 15 (1) ◽  
pp. 70-76 ◽  
Author(s):  
Francesco Paolo La Mantia ◽  
Manuela Ceraulo ◽  
Maria Chiara Mistretta ◽  
Marco Morreale
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Biodegradable Polymers ◽  
Biodegradable Polymer ◽  
Cold Drawing ◽  
Thermal Characterization ◽  
Systematic Investigation ◽  
Thermomechanical Properties ◽  
Polymer Systems ◽  
The Impact

Purpose Biodegradable polymers are currently gaining importance in several fields, because they allow mitigation of the impact on the environment related to disposal of traditional, nonbiodegradable polymers, as well as reducing the utilization of oil-based sources (when they also come from renewable resources). Fibers made of biodegradable polymers are of particular interest, though, it is not easy to obtain polymer fibers with suitable mechanical properties and to tailor these to the specific application. The main ways to tailor the mechanical properties of a given biodegradable polymer fiber are based on crystallinity and orientation control. However, crystallinity can only marginally be modified during processing, while orientation can be controlled, either during hot drawing or cold stretching. In this paper, a systematic investigation of the influence of cold stretching on the mechanical and thermomechanical properties of fibers prepared from different biodegradable polymer systems was carried out. Methods Rheological and thermal characterization helped in interpreting the orientation mechanisms, also on the basis of the molecular structure of the polymer systems. Results and conclusions It was found that cold drawing strongly improved the elastic modulus, tensile strength and thermomechanical resistance of the fibers, in comparison with hot-spun fibers. The elastic modulus showed higher increment rates in the biodegradable systems upon increasing the draw ratio.

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