The problems of the fracture mechanics hypotheses development are formulated with reference to the calculation of reinforced concrete structures in the presence of cracks. The main aspects of fracture mechanics are given. They focus on the features of the predestruction zone, as well as the hypotheses and assumptions underlying the calculation of reinforced concrete structures for the second group of limit states. It is described the features of cutting a two-cantilever element including a crack for constructing an effective instrument of calculation for reinforced concrete with allowance for physical nonlinearity, cracking processes, bond of reinforcement with concrete, and the effect of discontinuity. It is obtained a new solution to the problem of the stressed-strained state of the reinforced concrete element in the zone immediately adjacent to the crack.

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The development of fracture mechanics hypotheses applicable to the calculation of reinforced concrete structures for the second group of limit states

Now a days Brass is using in many industrial components like heat exchangers, bearings, valves etc. The present paper focused the principles of fracture mechanics of brass . The stress intensity factor (SIF) is an important factor in fracture mechanics. J-integral method has been adopted for SIF calculation. The values obtained by using J-Integral technique have been compared with that of displacement extrapolation technique and observed that they are in order. The residual strength of brass at various crack lengths are studied.

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Computation of stress intensity factor of brass plate with edge crack using j-integral technique

The paper addresses the use of small-sized specimens of various types, including those with deep (50%) side grooves, for the purpose of fracture toughness prediction. The experimental data for numerous (more than 500) small-sized specimens prepared from materials of various degrees of embrittlement are compared to the test results for full-sized specimens of C(T) type. The concepts of Master Curve and Unified Curve are applied for the processing of experimental data. To handle the test results for small-sized deep-grooved specimens a calculation procedure has been elaborated, which adjusts the calculation method specified in the ASTM Standard E 1921. We provide recommendations of how to use precracked Charpy type deep-grooved (50%) specimens for prediction of a representative temperature dependence of fracture toughness.

Analysis of applicability of small-sized specimens to prediction of temperature dependence of fracture toughness

We present theoretical approaches and a procedure for the FEM computation of parameters of nonlinear fracture mechanics in prismatic bodies with a crack. The efficiency of the proposed approaches and the veracity of the results obtained have been analyzed.

Solving linear and nonlinear three-dimensional problems of fracture mechanics by a semi-analytic finite element method. Part 1. Theoretical background and a study of efficiency of fem procedure for solving three-dimensional problems of fracture mechanics

This paper focuses on a failure potential for rotary elements used in the agricultural machinery. It presents a structural stress analysis case study which is a comparative analysis using analytical and numerical (finite element method) methods. In the case study, the motion transmission gears of a rotary drum mower have been considered, and the stress distribution on the transmission gears has been investigated considering real loading conditions which were obtained from experimental field operations. The experimental part of the case study was carried out within a clover field. The clover field was harvested by the drum mower, and the loading force on the transmission gears was calculated through torque data measured from tractor power take-off during the harvesting operation. Subsequently, the torque data were used in the finite element method based commercial code to simulate stress distribution on the transmission gears in the digital environment. The simulation results were validated by making comparisons between analytical calculations and simulation examinations based on the material failure criterion. The numerical results and visual print-outs indicated that there was a good correlation between simulation and analytical results, and the stress magnitudes on the transmission gears were within the safe-operating range against maximum dynamic loading conditions. The study presented a simulation-driven stress analysis case study, which contributes to further research into the utilization of engineering simulation technology for agricultural machinery/equipment design.

Analytical and Finite Element Method Based Stress Analysis of Rotary Elements: Case Study for the Motion Transmission Gears of a Rotary Drum Mower

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Naoto Sakakibara

Papers

Finite Element Method in Fracture Mechanics