Destruction Of Solid Materials Research Articles

Electric-impulse-technology: results of a basic investigation into the use of the technology as a selective demolition method in the construction industry

A large proportion of today's building projects are realized in existing buildings. This almost always requires the sensitive deconstruction of existing building fabric. Deconstruction technologies have to fulfill high requirements particularly in inner-city residential areas and during ongoing building use, both for construction projects in the existing building stock and for new construction activities. Currently used demolition technologies rarely meet the growing requirements in building practice. Common demolition and separation methods are characterized by high emissions, such as vibrations and noise, large quantities of blasting material, slow performance progress or high physical effort. An alternative technology is the electrodynamic Electric-Impulse-Technology (EIT). The process technology, initially developed for applications in mining and special civil engineering, is based on the destruction of solid materials by high-voltage pulses. On the basis of large-scale tests in mining dimensions, it was possible to demonstrate high dissolving capacities with low energy input. The research project aimed to investigate the basics for transferring the EIT to low-emission and selective material removal in civil and structural engineering. Extensive laboratory tests were conducted on sand-lime and concrete specimens to verify the adaptation of the EIT. It was found out that the technology is suitable for use in the construction industry. Further research is to be conducted to investigate the identified areas of application in greater depth and to further develop EIT for practical use.

"MODEL ACHIEVEMENT FOR IGNITION AND DEVELOPMENT OF STOCHASTIC DISCHARGE CHANNELS IN CONCRETE AND REINFORCED CONCRETE TAKING INTO ACCOUNT THE PROPERTIES OF THE MEDIUM AND THE GEOMETRY OF THE REINFORCING FRAME"

"The article develops a generalized model of electrodischarge action on concrete, which allows consistently describing phases of electro-explosion in condensed media: initiation and development of discharge channels, expansion, generation of shock waves, interaction of waves with the material being processed, deformation and destruction of solid materials. The model is based on a stochastic deterministic approach to the development of instability. processes associated with the distribution of the electric field, when mechanical stresses break. The flow of the process is considered deterministically on the basis of nonlinear integro-differential equations, local processes leading to the growth of the channel and cracks - stochastically. Equations describing the nature of the discharge development, the change of the channel resistance and its expansion are concordantly solved with the transition equations in the scheme of the real pulse generator. Expansion of the channel in the liquid is based on the law of conservation of energy, mass, pulse, equations of wave dynamics and allows to calculate the temporal and amplitude impact of shock waves from the channel on the barriers. The process of electrical breakdown of condensed dielectrics occurs with the development of a stochastically discharge structure, mainly determined by the emergence of highly conductive plasma channels. The development of the channel structure begins in the area of maximum field tension. In this case, the processes of phase transitions of a material directly determine the quantitative and qualitative processes of image of channels. As part of the study of the model, an analysis of the influence of the movement of electro-discharges on the redistribution of the electrostatic field, conditions leading to the direct formation of discharge channels, fracture formation and complete deformation was conducted. Keywords: model, electro-discharge device, stochastic-deterministic approach, electric field, mechanical voltage, shock wave, channel resistance, dielectric, pulse generator, differential equations."

МОДЕЛИРОВАНИЕ РАСПРЕДЕЛЕНИЯ НАПРЯЖЕНИЙ, ДЕЙСТВУЮЩИХ ПРИ РАЗРУШЕНИИ ПОРОДЫ В ДРОБИЛКАХ С УЧЕТОМ КОНТАКТНОГО ТРЕНИЯ

Приведены исследования распределения напряжений, действующих при разрушении крепких материалов в зоне контакта с бронеплитами в щековых дробилках со сложным движением щеки и с конусами в конусных дробилках. Проанализировано влияние направления сил контактного трения при сжатии на эффективность разрушения горной массы. Разработана математическая модель для определения напряженного состояния породы. Показана возможность управления режимами нагружения для повышения эффективности процесса дробления.

Mechanism of shock waves generation and material destruction in a wire induced surface flashover

Explosive wire induced surface flashover has been studied as a promising method for shock wave generation and destruction of solid materials. This method exhibits very high efficiency of electric energy transformation into the discharge and effective shock wave generation. The framing photography and were applied in order to clarify the discharge dynamics and the mechanism of the shock wave formation and propagation. The experiments performed allow to suggest the model of the pressure wave generation in the wire explosion process.