Pressure Loading Actuator (PLA)

The pressure loading actuator is an air-delivery system using advanced, adaptive control to replicate target pressure time histories. Coupled with pressure boxes, the PLA represents the main component of our pressure loading system.

detailed drawing of ona PLA unit

A blower (fan) is used to generate the required pressure rise and flow rates required, while a rotating disk inside the valve, controlled by a servo motor is used to regulate the pressure applied to the specimen.

The PLA(s) are controlled either individually or in a group over an Ethernet (CAT-5) network using a PC-based control program, which updates the position of the valve approximately 100 times a second. The performance of the PLA is governed by the fan curve of the blower, minus the minor losses through the connecting hoses and valve which defines the maximum possible pressure as a function of leakage flow rate.

The current blower can generate maximum and minimum pressures of 23 kPa and -20 kPa, respectively, and has a free air flow rate of 0.24 m3 /s. The frequency response of the system depends upon the fan curve and leakage flow rates so that tracking the most extreme temporal pressure gradients is limited by these factors.

Test control and measurement

Along with the fully-automated control of the pressure loading system, our instrumentation allows data acquisition on:

  • forces in essential components of the load-resisting system;
  • global deflections of the overall specimen and local deformations of components;
  • external and internal pressures generated by the ambient wind loads;
  • rain characteristics and moisture penetration data; and
  • the growth and airborne propagation of mould.

See also:

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Faculty of Engineering • Spencer Engineering Building
The University of Western Ontario
London, Ontario, Canada, N6A 5B9 • Tel: 519-661-2128

Updated June 22, 2010 by contactWE
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