Facility 400:  Mass Properties Measurement

 

Description: The MPMF is used to measure the weight, center of gravity (CG), moment of inertia (MOI), and product of inertia (POI) of large structural assemblies. The facility can also be used to balance payloads statically and dynamically.

 

 

The MPMF is portable and can be operated in clean rooms, or remotely operated in vacuum chambers at pressures down to 1.33 KPa (10 torr).

 

 

Mode of Operation: The machine contains a spherical air bearing that supports the measuring table and the test item. The control console is remotely connected to the MPMF by flexible cables and a GN2 line. The console controls the table’s motion and takes measurements of the unbalance moment, period of oscillation, and table rotational speed.

 

 

Weight Measurement: The facility is mounted on a Pennsylvania 6600 scale base platform (5.75’ L x 5.75’ W x 0.33’ H) which gives an immediate digital readout of the weight of the test specimen, regardless of its mounting position on the facility.

 

 

CG Measurement: The static unbalance (CG offset) is determined by measuring the moment created by a CG displaced from the measurement axis of the machine.

 

 

MOI Measurement: The MOI is determined by using the facility as an inverted torsional pendulum and measuring the period of oscillation about the geometrical axis of the machine.

 

 

POI Measurement: The POI (dynamic unbalance) is determined by rotating the MPMF at several different speeds, and measuring the moment.

 

Parameter                                                                

Test Weight: (maximum)           10,000 lbs (4,536 kg)

Table Dimensions:                      4’ (1.22 m) diameter mounting table

                                                       10’ (3.1 m) table is also available for large payloads

Moment Measurement:             30,000 in-lb (3,390 Nm)

 

Range: (maximum)       ±0.06 “(0.15 cm) for payload at 3’ (0.91 m) above table and displaced 1” (2.54 cm) from vertical axis ±0.12” (0.3 cm) for payload at 10’ (3.1 m) above table and displaced

 

CG Capability:                                                  1” (2.54 cm) from vertical axis

MOI Accuracy:                                                 1% of measured MOI

POI Accuracy:                                                  5% of measured POI

MPMF Table Speed:                                        0 to 200 RPM

Platform Scale Capacity:                               20,000 lb (9,072 kg)

GN₂ Flow Rate:                                                0.17 m³/minute (6.0 ft³/minute) standard

 

Rental Rate:  Inquire