On the contact problem of a moving rigid cylindrical punch sliding over an orthotropic layer bonded to an isotropic half plane

In this study, the frictional moving contact problem for an orthotropic layer bonded to an isotropic half plane under the action of a sliding rigid cylindrical punch is considered. Boundary conditions of the problem include the normal and tangential forces applied to the layer with a cylindrical punch moving on the surface of the layer in the lateral direction at a constant velocity V. It is assumed that the contact area is subjected to the sliding condition where Coulomb’⣙s law is used to relate the tangential traction to the normal traction. Using the Fourier integral transform technique and Galilean transformation, the plane contact problem is reduced to a singular integral equation in which the unknowns are the contact stress and the contact width. The singular integral equation is solved numerically using Gauss–Jacobi integration formulae. Numerical results for the contact widths and the contact stresses are given as a solution.

CHARACTERISTICS OF VIBRATIONS OF VISCOUS CONCRETE MEDIUM IN A VIBROFORM WITH CYLINDRICAL PUNCHES

The relevance of using volumetric vibroforming machines in the production of reinforced concrete products is considered. A step-by-step vibration effect created by the cylindrical surface of a punch fixed to the vibration form of a continuous formless forming machine is described. The expediency of achieving effective compaction by changing the vibration velocity is proved. The spread of vibration by a punch immersed in a viscous concrete medium is described. Analytical expressions describing changes in amplitude and phase variations of vibration propagation velocity in viscous concrete medium are obtained. Using the obtained analytical expressions, the corresponding graphical dependencies characterizing the impact on the concrete medium vibroform with punches, consisting of two parts that oscillate with different amplitude and frequency characteristics are constructed. The influence of the radial size r of cylindrical punch surface, frequency and amplitude of its oscillations on the change of amplitude and phase shift of vibration propagation velocity is established.

‘The punch technique’ for the soft tissue exposure of superficial, buccally impacted teeth

The management of impacted teeth can be complex, time-consuming and expensive for the patient and healthcare system. These cases often require referral to a different specialty which increases the overall treatment time and number of appointments. This article introduces a simple, efficient technique using a cylindrical punch biopsy instrument to expose superficial, buccally impacted upper permanent canines and incisor teeth in carefully selected cases. This patient- and operator-friendly technique avoids the need for a referral to a different specialty, gives the orthodontist autonomy of the position of the bond, allows immediate traction, thereby reducing the number of appointments and overall treatment time for the patient.