Fracture Mechanics Of Solids Research Articles

General particle dynamics: On the correlation of nonlocal and local theories for large deformation problems

This paper presents a detailed investigation on the General Particle Dynamics (GPD) method and its implications for addressing challenges in large deformation mechanics and fracture modeling. The GPD method integrates nonlocal interactions and nonlocal differential operators to overcome limitations of classical continuum mechanics in capturing long-range interactions and material behaviors under extreme deformation conditions. Through a systematic examination of the physical and mathematical foundations of GPD, including its governing equations and constitutive relations, we elucidate the robust and applicability of the proposed method in simulating complex deformation phenomena. Furthermore, the relationships among GPD, conventional mechanical theories (Smoothed Particle Hydrodynamics), nonlocal theory (Peridynamics) and Molecular Dynamic theories are discussed. Numerical examples related to large deformation and fracture problems are tested to verify the ability of the proposed method. The numerical results show that GPD inherits the advantages of the classical method and also has its unique properties in solid fracture mechanics and large deformation problems, making it a promising approach in computational mechanics.

Crack Width and Load-Carrying Capacity of RC Elements Strengthened with FRP

The present study focuses on a prediction of crack width and load-carrying capacity of flexural reinforced concrete (RC) elements strengthened with fibre-reinforced polymer (FRP) reinforcements. Most studies on cracking phenomena of FRP-strengthened RC structures are directed to empirical corrections of crack-spacing formula given by design norms. Contrary to the design norms, a crack model presented in this paper is based on fracture mechanics of solids and is applied for direct calculation of flexural crack parameters. At the ultimate stage of crack propagation, the load-carrying capacity of the element is achieved; therefore, it is assumed that the load-carrying capacity can be estimated according to the ultimate crack depth (directly measuring concrete’s compressive zone height). An experimental program is presented to verify the accuracy of the proposed model, taking into account anchorage and initial strain effects. The proposed analytical crack model can be used for more precise predictions of flexural crack propagation and load-carrying capacity.

THE DAMAGES OF BEARING CONSTRUCTION IN NOT CONSERVED BUILDINGS AND THE RESEARCH INTO THEIR SUITABILITY FOR FUTURE EXPLOATATION

There are frequent cases when load‐bearing reinforced concrete structures of not completed buildings are directly exposed to precipitation (rainfall, snowfall) and to environment of positive and negative temperature. Multihollowcore concrete slabs are especially vulnerable to such actions since investigations of condition of non‐conserved buildings indicate that these slabs can crack critically. Water accumulated in hollows of slabs and frozen under negative temperature can split concrete in vertical walls between hollows, inflict concrete cracking below hollows or spalling of large sections together with longitudinal reinforcement in them at the bottom of slabs. In performed investigations of condition of non‐completed and non‐conserved load bearing structures a modern method was employed for the determination of cracking in walls between hollows of slabs, using mini video‐camera. Analysis of cracking in slabs indicated that the character of cracking is governed by the quantity of water accumulated in a hollow at the moment of freezing and the level of freezing water in adjacent hollows of a slab and the compaction quality of concrete in a tensile zone of a slab as well. The analysis of pressure on the surface of hollows developed by ice set can be analysed employing a model of non‐linear analysis of COSMOS/M program and fracture mechanics of solids. Several versions of cracking in multihollowcore concrete slabs are possible, the most critical one of which is when a part of a bottom flange of a slab together with longitudinal reinforcement spalls off due to normal and shear deformations. The accomplished analysis allowed to establish kinetics of cracking for slabs and to evaluate their condition more reliably.

Acoustic emission prediction of the performance of metal-polymer machine parts

1. Above-described approach, based on the kinetic theory of strength and the microscopic fracture mechanics of solids and the use of the acoustic emission method, clearly shows a close connection between structural characteristics of metal-polymer joints and kinetic characteristics which characterize their failure. The method makes it possible to quickly (within 30–60 sec) and reliably evaluate the adhesive strength of such joints by a nondestructive method. 2. It was shown that a generalizing index of the serviceability of adhesive metal-polymer joints operating under loads is the slope of the time dependence of the logarithm of the number of AE signals obtained during the loading of the joint at a constant rate. It was also shown that this index can be determined fairly simply and that such a determination makes it possible to predict the serviceability and evaluate the quality of each part, speed up the development of optimum technologies for making such parts, and operationally improve their quality and reliability.

Fracture mechanics of solids in compression along cracks

The following results were obtained in regard to compression of solids along planes containing cracks. 1. For the case of loading examined, we proposed a criterion for the beginning of fracture corresponding to the stability criterion in the three-dimensional linearized theory of stability of deformable bodies. 2. An exact solution of a two-dimensional problem of local loss of stability was obtained for a finite number of plane cracks of constant width, when the cracks are infinite in one direction and located in one plane. This solution was obtained in general form for elastic compressible and incompressible bodies with Tinite and small subcritical strains and elastic-plastic compressible and incompressible bodies with small subcritical strains. 3. It was shown for specific models of isotropic elastic and elastic-plastic bodies that, within the framework of plane strain, loss of stability next to a finite number of plane cracks occurs in the form of surface instability of a half-space and half-plane. It was shown that flexural and symmetrical modes of instability have the same critical load.

Modern problems of fracture mechanics

Introduction. During recent decades on the boundary of the classic mechanics oi a solid being deformed, the physics of a solid, and the chemistry of surface phenomena there has been formulated a rapidly developing area of the science of the strength of materials -the fracture mechanics of solids. The scientific and practical interest in this area of science has been continuously increasing~ To no small degree this has been caused by its great value for investigating methods of determining the effectiveness of a material in a structure under extreme service conditions and also for creating constructional materials with high physicomechanical properties.