Effect of the features of functionalized structure on elastic properties and strength of partially-filled brittle porous materials

A two-scale mechanical model of brittle porous material partially filled with plastic filler (inclusions) was developed within the framework of the formalism of movable cellular automaton method. The model was applied to study the mechanical properties of mesoscopic samples with a linear distribution of the local porosity in the depth of the material. Calculation results showed essentially nonlinear dependence of their elastic and strength properties on the degree of pore space filling. It is found that depending on the sign of the gradient of porosity the value of shear strength of partially filled samples can significantly increase or remain constant with increase in the value of the degree of filling

Influence of vibrational treatment on thermomechanical response of material under conditions identical to friction stir welding

A molecular dynamics model was constructed to describe material loading on the atomic scale by the mode identical to friction stir welding. It was shown that additional vibration applied to the tool during the loading mode provides specified intensity values and continuous thermomechanical action during welding. An increase in additional vibration intensity causes an increase both in the force acting on the workpiece from the rotating tool and in temperature within the welded area

Influence of porosity percolation on mechanical properties of ceramic materials. 3D simulation using movable cellular automata

3D computer simulation of mechanical behavior of a brittle porous material under uniaxial compression is considered. The movable cellular automaton method, which is a representative of particle methods in solid mechanics, is used for computation. In an initial structure the automata are positioned in FCC packing. The pores are set up explicitly by removing single automata from the initial structure. The computational results show that the curves of dependence of strength and elastic properties of the modeled specimens on porosity have a break at the porosity value about 20 %, i.e. percolation threshold. The obtained results are in close agreement with available experimental data

Nonlinear Mechanical Effect of Free Water on the Dynamic Compressive Strength and Fracture of High-Strength Concrete

It is well-known that the effect of interstitial fluid on the fracture pattern and strength of saturated high-strength concrete is determined by qualitatively different mechanisms at quasi-static and high strain rate loading. This paper shows that the intermediate range of strain rates (10−4 s−1 < ε˙ < 100 s−1) is also characterized by the presence of a peculiar mechanism of interstitial water effect on the concrete fracture and compressive strength. Using computer simulations, we have shown that such a mechanism is the competition of two oppositely directed processes: deformation of the pore space, which leads to an increase in pore pressure; and pore fluid flow. The balance of these processes can be effectively characterized by the Darcy number, which generalizes the notion of strain rate to fluid-saturated material. We have found that the dependence of the compressive strength of high-strength concrete on the Darcy number is a decreasing sigmoid function. The parameters of this function are determined by both low-scale (capillary) and large-scale (microscopic) pore subsystems in a concrete matrix. The capillary pore network determines the phenomenon of strain-rate sensitivity of fluid-saturated concrete and logistic form of the dependence of compressive strength on strain rate. Microporosity controls the actual boundary of the quasi-static loading regime for fluid-saturated samples and determines localized fracture patterns. The results of the study are relevant to the design of special-purpose concretes, as well as the assessment of the limits of safe impacts on concrete structural elements

Effect of the features of functionalized structure on elastic properties and strength of partially-filled brittle porous materials

A two-scale mechanical model of brittle porous material partially filled with plastic filler (inclusions) was developed within the framework of the formalism of movable cellular automaton method. The model was applied to study the mechanical properties of mesoscopic samples with a linear distribution of the local porosity in the depth of the material. Calculation results showed essentially nonlinear dependence of their elastic and strength properties on the degree of pore space filling. It is found that depending on the sign of the gradient of porosity the value of shear strength of partially filled samples can significantly increase or remain constant with increase in the value of the degree of filling

Influence of vibrational treatment on thermomechanical response of material under conditions identical to friction stir welding

A molecular dynamics model was constructed to describe material loading on the atomic scale by the mode identical to friction stir welding. It was shown that additional vibration applied to the tool during the loading mode provides specified intensity values and continuous thermomechanical action during welding. An increase in additional vibration intensity causes an increase both in the force acting on the workpiece from the rotating tool and in temperature within the welded area

Study of the mechanical properties of ceramic composites with different volume of plastic filler

AbstractStudying of mechanical properties of brittle heterogeneous materials with different structural parameters, in particular value of porosity and volume of inclusions is very important for both fundamental science and practical applications. Therefore, in this paper a multiscale computer model of mechanical behaviour of ceramic composites with different porosity and filler-containing pore fraction under shear loading was proposed. The model was developed in the framework of movable cellular automaton method. On the basis of numerical calculations an analytical evaluation for the dependence of shear strength and elastic modulus of the material on its total porosity and fraction of pores containing filler was proposed

Influence of porosity percolation on mechanical properties of ceramic materials. 3D simulation using movable cellular automata

3D computer simulation of mechanical behavior of a brittle porous material under uniaxial compression is considered. The movable cellular automaton method, which is a representative of particle methods in solid mechanics, is used for computation. In an initial structure the automata are positioned in FCC packing. The pores are set up explicitly by removing single automata from the initial structure. The computational results show that the curves of dependence of strength and elastic properties of the modeled specimens on porosity have a break at the porosity value about 20 %, i.e. percolation threshold. The obtained results are in close agreement with available experimental data