Further developments in stress initialization in geomechanics via FEM and a two-step procedure involving airy functions

The in-situ stress field in rock masses is a key aspect when a numerical analysis of a rock mass is carried out in any area of geo-engineering, such as civil, mining, or Oil & Gas. A method for the numerical generation of the in-situ stress state in the FE context, based on Airy stress functions was previously introduced. It involves two steps: 1) an estimate of the stress state at each Gauss point is generated, and 2) global equilibrium is verified and re-balancing nodal forces are applied as needed. In this paper, new developments towards improving the accuracy of the stress proposal are discussed. A real application example has been used to illustrate the results achieved with the new implementation

Thermodynamic Investigation of a Modified Compression Ignition Engine Fueled by Diesel Biodiesel Ethanol Blends

The present study contrasts the thermodynamics analysis of modified diesel engines with traditional diesel engines. Thermodynamics study is done by the use of energy and exergy analysis for diesel, B20 (blend of 80 per cent diesel by volume with 20 per cent mahua biodiesel) and LHR modification and LTC 15 per cent EGR fuelled with B20 blend and 5 per cent ethanol with various loads ranging from no load to full load. Implemented two technologies for increasing engine efficiency. One of the primary techniques is the Low Heat Rejection (LHR) concept (or the so-called “Adiabatic” engine) applied. In the engine cylinder, a ceramic layer of Alumina (Al2O3) was used to modify the Low Heat Rejection (LHR). Another technique is Low-temperature combustion (LTC) modes are added by joining the inlet and exhaust pipes through valves to control the exhaust gas at an optimal rate of 15 per cent. The findings of energy and exergy distribution in the engine were compared using optimum alterations with fuel blends such as 20 per cent mahua biodiesel and 5 per cent ethanol. From energy distribution, best shaft power (QBP) (2.8kW) is transformed from heat input observed in the optimum altered engine at full load conditions compared to others. Due to modifications employed in the engine and fuels. Maximum unaccounted energy (QUN) loss in diesel (44 %). And highest thermal efficiency (31.2 %) is revealed in B20E5 (LHR+15 % LTC). From exergy distribution, it noticed that the same trend of energy distribution and at 100 per cent load condition, maximum (12.54kW) in diesel and minimum (8.45 kW) in B20E5 (LHR+15 % LTC) has obtained input availability (Ain).The maximum conversion rate of availability in brake power (Abp) (0.61 kW) in B20 (LHR). Compared to diesel, second law or exergetic efficiency more in B20E5 (LHR+15 % LTC).&nbsp

Zero-thickness interface elements with h-m coupling, formulation and applications in geomechanics

Previous developments on zero-thickness interface elements for coupled Hydro-Mechanics problems are briefly described, followed by some new geomechanical applications, particularly to hydraulic fracture in rock. The results are compared satisfactorily to approximate formulas and previously published numerical results. Once verified, the model is applied to new cases to show the capabilities of the approach

Zero-thickness interface elements with h-m coupling, formulation and applications in geomechanics

Previous developments on zero-thickness interface elements for coupled Hydro-Mechanics problems are briefly described, followed by some new geomechanical applications, particularly to hydraulic fracture in rock. The results are compared satisfactorily to approximate formulas and previously published numerical results. Once verified, the model is applied to new cases to show the capabilities of the approach