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In this work, Hui-Shia model is developed to reveal the efficiency of a deficient interphase on the tensile modulus of polymer halloysite nanotube (HNT) nanocomposites. "Lc" as essential HNT length providing full stress transferring is defined and effective HNT size, effective HNT concentration, and efficiency of stress transferring (Q) are expressed by "Lc". Furthermore, the influences of all terms on the "Q" and nanocomposite's modulus are clarified, and also the calculations of the model are linked to the tested data of some nanocomposites. Original Hui-Shia model overpredicts the moduli, but the innovative model's predictions appropriately fit the measured data. Lc = 200 nm maximizes the sample's modulus to 2.6 GPa, but the modulus reduces to 2.11 GPa at Lc = 700 nm. Therefore, there is a reverse relation between the sample's modulus and "Lc". Q = 0.5 produces the system's modulus of 2.1 GPa, while the modulus of 2.35 GPa is achieved at Q = 1 providing a direct relation between the nanocomposite's modulus and "Q". Generally, narrow and big HNTs, along with a low "Lc", enhance the "Q", because a lower "Lc", reveals a tougher interphase improving the stress transferring. [ABSTRACT FROM AUTHOR]

Abstract In this work, Hui-Shia model is developed to reveal the efficiency of a deficient interphase on the tensile modulus of polymer halloysite nanotube (HNT) nanocomposites. “Lc” as essential HNT length providing full stress transferring is defined and effective HNT size, effective HNT concentration, and efficiency of stress transferring (Q) are expressed by “Lc”. Furthermore, the influences of all terms on the “Q” and nanocomposite’s modulus are clarified, and also the calculations of the model are linked to the tested data of some nanocomposites. Original Hui-Shia model overpredicts the moduli, but the innovative model’s predictions appropriately fit the measured data. Lc = 200 nm maximizes the sample’s modulus to 2.6 GPa, but the modulus reduces to 2.11 GPa at Lc = 700 nm. Therefore, there is a reverse relation between the sample’s modulus and “Lc”. Q = 0.5 produces the system’s modulus of 2.1 GPa, while the modulus of 2.35 GPa is achieved at Q = 1 providing a direct relation between the nanocomposite’s modulus and “Q”. Generally, narrow and big HNTs, along with a low “Lc”, enhance the “Q”, because a lower “Lc”, reveals a tougher interphase improving the stress transferring.

Abstract The stress concentration caused by the presence of the remaining coal pillar in the overlying goaf can easily cause large deformation of the roadway in the lower seam and other problems. To solve this problem, the reasons for stress concentration caused by the remaining coal pillar in the overlying goaf were analyzed. A hydraulic fracturing method for relieving stress concentration has been proposed. By using hydraulic fracturing technology to remove the hanging roof on both sides of the coal pillar and weaken the coal pillar system, high stress is transferred to the goaf. The degree of stress concentration in coal pillars and surrounding rock of roadway can be reduced by 47% and 26%, respectively. This method can also solve the stress concentration problem of the remaining ore pillar in the overlying goaf of the metal ore. This method has been applied in the coal mine. The deformation of the surrounding rock of the test roadway after hydraulic fracturing has been reduced by more than 60%.

The stress concentration caused by the presence of the remaining coal pillar in the overlying goaf can easily cause large deformation of the roadway in the lower seam and other problems. To solve this problem, the reasons for stress concentration caused by the remaining coal pillar in the overlying goaf were analyzed. A hydraulic fracturing method for relieving stress concentration has been proposed. By using hydraulic fracturing technology to remove the hanging roof on both sides of the coal pillar and weaken the coal pillar system, high stress is transferred to the goaf. The degree of stress concentration in coal pillars and surrounding rock of roadway can be reduced by 47% and 26%, respectively. This method can also solve the stress concentration problem of the remaining ore pillar in the overlying goaf of the metal ore. This method has been applied in the coal mine. The deformation of the surrounding rock of the test roadway after hydraulic fracturing has been reduced by more than 60%. [ABSTRACT FROM AUTHOR]

In this study, the shear-lag model considering the micro-structure “interphase” and the two separate micro-damages, “interphase” debonding and matrix damage, in single fiber composite is developed firstly. So the more actual stress distribution on the fiber fragmentations during the process of stress transferring in single fiber composite is obtained. Then based on the present shear-lag model, the Monte-Carlo simulation for the process of the single-fiber fragmentation is established to predict the number of fiber fragmentation during the process of the test. The predicted result of the simulation is in accordance with the result of the single-fiber fragmentation test. At last, the factors including the statistical parameter of fiber strength distribution, the properties of the matrix and the state of the “interphase” in the single fiber composite, which affect the process of single-fiber fragmentation are analyzed. [ABSTRACT FROM AUTHOR]