PSI - Issue 44

Mauro Mazzei et al. / Procedia Structural Integrity 44 (2023) 1212–1219 Mauro Mazzei et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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where C0 is a constant, x the unknown displacement, d0 is the rest position distance of the proof moving mass and the fixed facing plates. In term of the actual acceleration to be measured this translates to: a = x KTotal/ Ms where KTotal elastic constant of the proof mass suspending spring, Ms is the proof suspended mass and x the computed displacement. Let's see how these general parameter translate to an effective design. Exactly starting from proof mass weight, 200 g approximately matching the one of the excellent ISA accelerometer, let's see how we may design an acceleration detection module with the proper sensitivity, not too much affected, by the simplifications we must necessarily introduce for cost savings. Let's assume a proof mass made by two Aluminum blocks halves each quoting:

Table 1.

Parameter

Value

Al density [g/cm^3]

2,71

dim X [cm] dim Y [cm] dim z [cm]

8 8

0,6

Half side weight [g]

104,064

Within each we remove from the face centre in a symmetrical manner a mass 8 x 3 x 0,1 mm to house a steel strip, then each half will weight: 104,64g -6,48g= 97,584 g.

Fig. 3. Extruded mass element.

Let's suppose now to keep a clearance all around the block of 1 cm then to grip the protrude steel strip in a frame such as the suspended mass will be free to oscillate only in the direction perpendicular to the centre of such a frame. Let's choice a steel strip of Y module of about 200 GP. We may then assume that on each side the following scheme apply:

Fig. 4. Steel lame flexion model.