MTS 85X Damper - Manual (Page 15)

Typical Test System Configuration
Damper System Operation Introduction 15
Servohydraulic and Mechanical Components
The following paragraphs briefly describe the servohydraulic and mechanical
components that are typical supplied with the MTS Landmark System.
Load frame
There are a variety of load frames that can be supplied with the system. The load
frame is the mechanical foundation of the test system in which the load cell
transducer, specimen fixturing or grips, and hydraulic actuator are mounted.
The load frame can be configured with hydraulic-controlled crosshead locks and
lifts that allow convenient crosshead positioning during specimen installation.
(Manual crosshead locks and lifts and manual crosshead locks and hydraulic lifts
are also available.)
Hydraulic actuator
The hydraulic actuator is typically mounted in the base of the load frame; some
load frames can have crosshead mounted actuators. It is the force-generating and/
or positioning device in the system. Hydraulic fluid is applied to either side of the
actuator's piston to cause its piston rod to extend or retract.
Servovalve(s)
The servovalve converts a control signal (from the test controller) to control the
direction and amount of fluid flow to the actuator. This regulated hydraulic fluid
flow controls the displacement or force being applied to the test specimen.
Hydraulic power
supply
The hydraulic power unit (HPU) provides pressurized hydraulic fluid to the
servovalve. An HPU typically includes a reservoir for the hydraulic fluid, a pump
to pressurize the hydraulic fluid, a motor to run the pump, a heat exchanger to
cool the hydraulic fluid, and sensors to monitor the level, pressure, and
temperature of the hydraulic fluid.
Transducer(s)
The load cell transducer, mounted underneath the load frame crosshead, is used
to measure the polarity and magnitude of the force that is applied to the
specimen.
The extensometer is a sensor attached to a specimen that measures a dimensional
change (gage length or strain) that occurs in the specimen while being tested.
Extensometers use a Wheatstone bridge circuit to detect the dimensional
changes. Extensometers are an option purchased separately.
The LVDT (linear variable differential transformer) transducer is mounted inside
the hydraulic actuator. The LVDT is used to measure the position (or
displacement) of the actuator piston rod.
Specimen fixtures or
grips
Either fixtures or grips are used to hold the specimen in alignment with the force
train during the test. The force train is comprised of the servohydraulic and
mechanical components which receive the forces applied by the hydraulic
actuator. Fixtures or grips are options purchased separately.
Test area enclosure
Protective enclosures should be used when you work with hazardous test
specimens (for example, ejected fluids if a damper breaks, brittle or fragmenting
materials, or materials that are internally pressurized). The enclosure is also
intended to limit access during a test. Test area enclosures are an option
purchased separately.