Determination of the Fundamental Frequency of Perforated Rectangular Plates: Concentrated Negative Mass Approach for the Perforation

Table 2

Coordinates of the perforation centers.

Specimen size (mm × mm)	Coordinates of the perforation centers (𝑥 mm, 𝑦 mm)
𝑎 × 𝑏	𝑎/4, 𝑏/4	𝑎/4, 2𝑏/4	𝑎/4, 3𝑏/4	2𝑎/4, 𝑏/4	2𝑎/4, 2𝑏/4	2𝑎/4, 3𝑏/4	3𝑎/4, 𝑏/4	3𝑎/4, 2𝑏/4	3𝑎/4, 3𝑏/4
138 × 216	34.5, 54	34.5, 108	34.5, 162	69, 54	69, 108	69, 162	103.5, 54	103.5, 108	103.5, 162
276 × 432	69, 108	69, 216	69, 324	138, 108	138, 216	138, 324	207, 108	207, 216	207, 324