Strength Analysis of EK-18 Excavator Bucket Construction for Mounting of Anti-adhesive Devices

Abstract

3D rigid-body model of a bucket of power shovel EK-18 was built using modern CAD (Computer Aided Design) software. A tetrahedral grid with 10-node second-order elements was chosen, and the given model was imported to APM WinMachine -model preparation preprocessor for finite element analysis. A finite element model was based on the geometrical model, imported from KOMPAS-3D to APM Studio. Calculation of the stressed-strained state of the bucket was carried out under the forces emerging while digging with "back hoe" equipment. Shift, deformation and tension charts were planned and the most and the least strained areas were pointed out. Wet coherent soil excavation deals with soil adhesion to working bodies of power shovels and leads to reduced performance. Performance decrease is caused by a reduction of useful bucket capacity and partial unloading, increased front resistance to cutting (digging) caused by wet soil adhesion to a working body, increased bucket entry resistance, increased idle time caused by necessity to clean working bodies. Also energy losses increase and quality of work drops because friction forces go up. Friction force while digging and levelling account for 30…70 percent of total digging resistance while performance decreases 1.2…2 times and more. Vibrothermal exposure creates new technological effect which involves a wider humidity range of efficient application and a reduction of friction forces. Disintegrating adhesion bonds with heating requires less driving force from the vibrator. Vibration boosts up heating of the contact layer, which reduces thermal energy losses. However, the question of piezoelectric ceramic actuators location on the excavator bucket needs to be dealt with. The most suitable spots for mounting piezoelectric ceramic devices for reducing soil adhesion to the excavator bucket were defined. Their efficiency is derived from combined (vibrothermal) methods of exposure. Such devices eliminate soil adhesion to bucket and increase efficiency of using power shovels with wet coherent soils.