Shear Strength Of Metal Research Articles

Model for calculation of anchor parameters fixings for vertical exploration works

It is known that effective rock hardening, as opposed to the action of tensile stresses, can be performed using anchors of various designs, depending on the specific mining and geological conditions. At the same time, there are very few publications on the calculation of roof bolting parameters for vertical shafts of different cross-sections. Therefore, in this work, a method has been developed for calculating such a support for vertical shaft shafts. Calculations were made only for the working wall, which is more dangerous in terms of fallout. Anchors are considered to work in tension when this wall is attached. For the opposite wall, such calculations are not required. Considering that here the anchors are being introduced in a direction perpendicular to the direction of bedding of rocks and they will work on a cut. In this case, the shear strength of metal and reinforced concrete anchors is 4-5 times higher than their tensile strength. The calculation method consists of methods for determining the lengths of the anchor and its locking part. In this case, the length of that part of the anchor is taken into account, which is enclosed between the base of the cone of influence of the anchor and the border of the zone of possible fallouts. The resulting formula for the length of the joint part of the anchor strongly differs from the previously known similar formulas by other authors, taking into account the effect of rock pressure, which varies with depth. Its structure contains the factor of the bedding angle with respect to the horizon and the coefficient of friction of the rock about the rock, leading to a decrease in the length of the anchor lock part. In addition, the volume of destroyed rocks in the zone of influence of the anchor is taken as the volume of the cylinder, which corresponds to the actual operating conditions of the anchor.

Shear strength of metals under uniaxial deformation and pure shear

In this paper, we investigate the dynamic shear strength of perfect monocrystalline metals using the molecular dynamics simulation. Three types of deformation (single shear, uniaxial compression and tension) are investigated for five metals of different crystallographic systems (fcc, bcc and hcp). A strong dependence of the calculated shear strength on the deformation type is observed. In the case of bcc (iron) and hcp (titanium) metals, the maximal shear strength is achieved at the uniaxial compression, while the minimal shear strength is observed at the uniaxial tension. In the case of fcc metals (aluminum, copper, nickel) the largest strength is achieved at the pure shear, the lowest strength is obtained at the uniaxial compression.

All in an engineer’s life

All in an engineer’s life

Shear strength of metals behind shock fronts

Results are presented from a numerical modeling of experiments, conducted by J. Lipkin, R. Asay, L. Chabildas, and J. Wise, in which shock-compressed aluminum and polycrystalline beryllium were loaded again by shock waves. Reproduction of the experimental structures of the impulses in the calculations made it possible to determine the stresses acting in the materials during the primary and secondary shock loading, as well as to study the dynamics of the secondary shock load. It is shown that resistance to plastic strain is maintained in aluminum and beryllium behind the front of weak shock waves with intensities up to 10 GPa. The shear strength of the material behind the front does not correspond to the shear stresses at the Hugoniot elastic limit. For aluminum alloy 6061-T6 and beryllium, shear strength behind the fronts of shock waves with amplitudes up to 10 GPa is lower than in the elastic precursor but is greater than the static yield point of the material in the initial state.