Study Two-Dimensional and Three-Dimensional of the Stress Concentration of the Traction Arm of the NEW HOLLAND TT75 Tractor in Service in CHAD

The New Holland TT75 tractors currently in service in Chad use a tractor arm with three holes, the middle one of which has recurrent failures due to traction. The purpose of this work is to use a finite element model to provide an improvement by modifying the geometric parameters to avoid premature failure of the tractor arms of the New Holland TT75. The ultimate force formula of Eurocode 3 was used to determine the maximum pressure to be applied and. A comparative traction study between the current arm and the proposed arm was performed, taking into account the variation in hole size, arm width and applied pressure for the determination of the stress concentration factor Kt. With the determination of Kt and for the arm width (w) less than or equal to 85 mm;the results showed that the proposed arm geometry is better.

Maximum Effective Hole Mathematical Modei and Exact Solution for Commingled Reservoir

The maximum effective hole-diameter mathematical modei describing the flow of slightly compressible fluid through a commingled reservoir was solved rigorously with consideration of wellbore storage and different skin factors. The exact solutions for wellbore pressure and the production rate obtained from layer j for a well production at a constant rate from a radial drainage area with infinite and constant pressure and no flow outer boundary condition were expressed in terms of ordinary Bessel functions. These solutions were computed numerically by the Crump's numerical inversion method and the behavior of systems was studied as a function of various reservoir parameters. The modei was compared with the real wellbore radii modei. The new modei is numerically stable when the skin factor is positive and negative, but the real wellbore radii modei is numerically stable only when the skin factor is positive.

Blasting technologies of vibration damping in subway tunnel passing under upper buildings closely

Reducing the blasting vibration is important for blasting excavation in subway tunnel construction.Taking the 3rd bid section of Line 3 of Qingdao subway project as an example,the distance between tunnel vault and ground is 5 ~ 8 m.In order to insure the safety of the upper buildings,technologies of parallel cut with large diameter empty hole,one-time initiation and delay by parts,and multiple shallow holes were adopted in the project.The results showed that the maximum value of vertical vibration was limited in the criterion allowance,and the upper buildings were not damaged.Besides,problems were solved that the number of nonel detonator was difficult to meet the requirements of excavating a large cross-section tunnel by blasting,multiple cross-section could’t be initiated simultaneously,and construction efficiency was low,which ensure the construction safety and schedule.

Exploration and determination of the principles of rotary-percussive underground slimhole drilling

A possibility of the efficient use of rotary percussive drilling to provide drilling smaller diameter holes(40–70 mm) both in mining and prospecting is disclosed herein. A new construction designed for the nipple thread connection is described. The relative amplitude variation, change of power pulse time and energy in their propagation throughout the drilling tool are determined. A possibility of the efficient power pulse transfer along the drill string to the rock destruction tools with new nipple connections which allow automating the make-up and breakout system of drill pipe was supported by experiments.

Analysis and Prediction of Hole Penetrated in Thin Plates under Hypervelocity Impacts of Cylindrical Projectiles

The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.