scholarly journals Modelling of Microperforated Panel Absorbers with Circular and Slit Hole Geometries

Acoustics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 665-678
Author(s):  
Pedro Cobo
Keyword(s):  
3D Printing ◽  
Thin Plate ◽  
Fluid Model ◽  
Original Proposal ◽  
Circular Holes ◽  
Absorption Performance ◽  
Hole Geometry ◽  
Microperforated Panels

Although the original proposal of microperforated panels by Maa consisted of an array of minute circular holes evenly distributed in a thin plate, other hole geometries have been recently suggested that provide similar absorption curves to those of circular holes. With the arrival of modern machining technologies, such as 3D printing, panels microperforated with slit-shaped holes are being specially considered. Therefore, models able to predict the absorption performance of microperforated panels with variable hole geometry are needed. The aim of this article is to analyze three models for such absorbing systems, namely, the Maa model for circular holes, the Randeberg–Vigran model for slit-shaped holes, and the Equivalent Fluid model for both geometries. The absorption curves predicted for these three models are compared with the measured curves of three panels microperforated with spirally shaped slits.

Minimization of Ovality of Circular Holes in Drilling Process

2015 ◽  
Vol 799-800 ◽  
pp. 393-396
Author(s):  
Parth Pandya ◽  
Vaibhav Shah ◽  
Ahamed H.M.S. Parvezsh ◽  
Prakash R. Apte
Keyword(s):  
Automobile Industry ◽  
Parametric Design ◽  
Angular Position ◽  
Drilling Process ◽  
Hole Center ◽  
Circular Holes ◽  
Hole Geometry ◽  
High Level ◽  
Aforementioned Factor ◽  
Subsequent Failure

In drilling and boring process, the relief in clamping stress causes deformations that cause variations in the geometry of the drilled hole. In automobile industry, when such holes are used to hold gear systems or rods in place, this variation in geometry leads to poor fitting and subsequent failure. To avoid this, high level accuracy is required which is both expensive and time-consuming. Therefore, a high percentage of such drilled parts are rejected in industry. The present paper addresses this problem by characterizing the variations in hole geometry as a function of clamping force, hole diameter, hole eccentricity (distance of hole-center from center of drilled face) and angular position of hole with respect to clamp location. The analysis result quantifies the comparative effect of each aforementioned factor on hole geometry variation. Taguchi Method based Design of Experiments using L25 orthogonal array has been used for performing the parametric design to arrive at the best settings of the 4 parameters. The optimal settings minimize ovality and displacement of the hole-center, and thus increase hole-fitting and its reliability against manufacturing variability.

Punching Force Reduction with Wave-Formed Tools

2007 ◽  
Vol 344 ◽  
pp. 209-216 ◽  
Author(s):  
Jussi A. Karjalainen ◽  
Kari Mäntyjärvi ◽  
Martti Juuso
Keyword(s):  
Cutting Force ◽  
Experimental Work ◽  
Tool Geometry ◽  
Material Strength ◽  
Test Results ◽  
Electro Discharge Machining ◽  
Lateral Forces ◽  
Circular Holes ◽  
Hole Geometry ◽  
Force Reduction

Flat-end tools are the most general types used in sheet metal punching and nibbling. They are geometrically simple and easy to sharpen but, on other hand, their cutting forces are relatively large, and hence the cutting process is frequently noisy. In order to reduce both cutting force and noise tools with one-way or two-way shearing have been utilised. The major drawbacks of these tools are the asymmetry of cutting easily causing non-circular holes with round tools, lateral forces with one-way shearing, excessive forming during cutting and more complex tool geometry to maintain. Here a new geometry for a punch is employed. The shearing edge is a sinus curve with several peaks making the cutting edge circularly symmetric and the phenomenon totally balanced. This means smaller forming forces, particularly in cases when also the radial form is concave. The geometry is without doubt more complex compared to the flat-end tool but rather easy to produce by multi-axis milling and electro-discharge machining. In the current work a set of experimental punches has been designed, manufactured and tested. A simple analytical theory for cutting force has also been derived and compared with the test results. The results show that the new geometry produces very precise hole geometry with a lower cutting force compared to conventional flat-end tools. Of course, more theoretical and experimental work is required to optimise the tool geometry including the tool clearance for each pair of material strength and thickness.

scholarly journals Flexural Wave Propagation in a Thin Plate with Circular Holes

1973 ◽  
Vol 16 (97) ◽  
pp. 1045-1052 ◽  
Author(s):  
Hideo SAITO ◽  
Kosuke NAGAYA
Keyword(s):  
Wave Propagation ◽  
Thin Plate ◽  
Flexural Wave ◽  
Circular Holes ◽  
Flexural Wave Propagation

Transverse Flexure of a Thin Plate Containing Two Circular Holes

1959 ◽  
Vol 26 (1) ◽  
pp. 55-60
Author(s):  
O. Tamate
Keyword(s):  
Stress Concentration ◽  
Thin Plate ◽  
Elastic Plate ◽  
Equal Size ◽  
Thin Elastic Plate ◽  
Two Circular Holes ◽  
Circular Holes ◽  
Axes Of Symmetry ◽  
Kirchhoff Theory

Abstract The problem of finding stress resultants in a thin elastic plate containing two circular holes of equal size, under plain bending about the axes of symmetry, has been discussed on the basis of the Poisson-Kirchhoff theory. A method of perturbation is adopted for the determination of parametric coefficients involved in the solution. The factors of stress concentration are calculated and compared with the results available.

Sign in / Sign up

Export Citation Format

Share Document