Roll forming process is used for manufacturing sheet metal parts by successive bending and creating the final shape with gradual deformation. In this article, deformation of a pre-punched sheet due to the roll forming process was studied. Two main defects in the roll forming process are ovality of holes and bow defect. The ovality of the hole is influenced by the process parameters including sh...

in this paper the dynamic of a droplet on a surface with a hole is investigated under gravitational effect by using lattice boltzmann method. incompressible two-phase flow with high density ratio proposed by lee is considered. cahn’s theory is used to observe the wettability of the surface in contact with liquid and gas phases. several parameters such as contact angle, surface tension and gravi...

In this research, the effects of the rotational speed, feed rate, tool material and lubricants on the tool life and the hole quality are studied in the frictional drilling of the titanium sheets. The friction drilling tests are performed on a CNC milling machine. Furthermore, 5 specimens are selected and their metallurgical structures are studied. The results show thatamong the input parameters...

In this paper, the stress concentration around a hole in the single layer composite materials with long fibers is examined. The single layer has an infinite length, limited with and instant thickness and is loaded by a constant tension force p at infinity. The width of the lamina is considered to be finite and bears a hole as a defect. Due to presence of excessive shear stress in the matrix bay...

We study the relation between the SL(2, R)/U(1) black hole and the c = 1 Liouville theory. A deformation, which interpolates the BRST operators of both models, is explicitly constructed. This interpolation is isomorphic, and the physical spectrum of the black hole is equivalent to that of the c = 1 model tensored by a topological U(1)/U(1) model. Some implications of the deformation are discuss...

In structures, stress concentration is a factor of fatigue fracture. Basically, the stress concentration is a phenomenon that should be avoided. However, it is difficult to avoid the stress concentration. Therefore, relaxation of the stress concentration is important. The stress concentration arises from notches and circular holes. There is a relaxation method that a composite patch covers a no...

s. We have studied phonon hole burning phenomenon. According to the plastic deformation model proposed by us, some characteristics of holes depend on the amplitude of resonant oscillation exited and the crystal condition of specimen. We studied the effect of heat treatment for the particles on holes. In NH4HZP04 specimen, the increase of decay time for oscillation and larger holes were found. N...

The deformation potentials a, b and d for GaAs have been determined from polarized photoluminescence measurements upon a set of epitaxially grown strained.GaAs structures possessing varying levels of compressive biaxial lattice strain. X-ray diffraction measurements yield values for the degree of lattice strain while the polarized photoluminescence measurements permit a separate determination o...

abstract: the equal channel angular rolling (ecar) is one of the severe plastic deformation processes, which can develop a shear deformation into a sheet metal. in this process, internal stresses are created due to the different strain levels experienced in different locations at the same time. the incremental hole drilling method is an effective technique for the evaluation of the through-thic...