Elasticity (Stiffness)
In this test, the equivalent stiffness of the perforated material is used in place of the stiffness of the solid material. By evaluating the effect of the perforations, the equivalent effective elastic modulus of the perforated material, E*, is obtained as a function of the elastic modulus of the solid or unperforated material, E. In addition, the effective Poisson's Ratio, v*, of the perforated material is obtained. This Poisson's Ratio may be used in cases where correction for load biaxiality is important.
| IP Numbers |
Hole Dia. |
Centers |
Holes Per sq. in. |
Open Area |
E*/E |
| 100 |
.020" |
.043" |
625 |
20% |
.565 |
| 106 |
1/16" |
1/8" |
73.9 |
23% |
.529 |
| 107 |
5/64" |
7/64" |
96.5 |
46% |
.246 |
| 108 |
5/64" |
1/8" |
73.9 |
35% |
.362 |
| 109 |
3/32" |
5/32" |
47.3 |
33% |
.395 |
| 110 |
3/32" |
3/16" |
32.8 |
23% |
.529 |
| 112 |
1/10" |
5/32" |
47.3 |
38% |
.342 |
| 113 |
1/8" |
3/16" |
32.8 |
40% |
.310 |
| 114 |
1/8" |
7/32" |
24.1 |
30% |
.436 |
| 115 |
1/8" |
1/4" |
18.5 |
23% |
.529 |
| 116 |
5/32" |
7/32" |
24.1 |
46% |
.249 |
| 117 |
5/32" |
1/4" |
18.5 |
35% |
.362 |
| 118 |
3/16" |
1/4" |
18.5 |
51% |
.205 |
| 119 |
3/16" |
5/16" |
11.8 |
33% |
.395 |
| 120 |
1/4"" |
5/16" |
11.8 |
58% |
.146 |
| 121 |
1/4" |
3/8" |
8.2 |
40% |
.310 |
| 122 |
1/4" |
7/16" |
6.0 |
30% |
.436 |
| 123 |
1/4" |
1/2" |
4.6 |
23% |
.529 |
| 124 |
3/8" |
1/2" |
4.6 |
51% |
.205 |
| 125 |
3/8" |
9/16" |
3.6 |
40% |
.310 |
| 126 |
3/8" |
5/8" |
3.0 |
33% |
.395 |
| 127 |
7/16" |
5/8" |
3.0 |
44% |
.265 |
| 128 |
1/2" |
11/16" |
2.4 |
48% |
.230 |
| 129 |
9/16" |
3/4" |
2.1 |
51% |
.205 |
| 130 |
5/8" |
13/16" |
1.7 |
54% |
.178 |
| 131 |
3/4" |
1" |
1.2 |
51% |
.205 |
|
 The effective elastic constants presented herein are for plane stress conditions and apply to the in-plane loading of the thin perforated sheets of interest. The bending stiffness of such perforated sheets is somewhat greater. However, most loading conditions involve a combination of bending and stretching, and it is more convenient to use the same effective elastic constants for the combined loading conditions. The plane stress effective elastic constants given herein can be conservatively used for all loading conditions. Using these effective elastic properties, the designer is able to determine the deflections of the perforated sheet for any geometry of application and any loading conditions using available elastic solutions. It is, therefore, easy for the designer to determine what additional thickness of the perforated material will provide stiffness equal to that of unperforated material.
Figure 4: Effective Elastic
Modulus, E*, and Poisson’s Ratio,
v*, vs. Percent Open Area
THIS MATERIAL WAS DEVELOPED FOR THE
IPA BY O’DONNELL & ASSOCIATES, INC. |
