Material Testing

Overview

The group is self-sufficient with the measurement and analysis software development. Our research instruments are built and customized for the special needs of the studies and the software must be adaptive for many different purposes. During the years we have built many applications that have also been continuously updated and modified to fulfil our requirements.

Mechanical testing

There are two similar custom-build fine material testing instruments. Newport Ultra-Precision Motion Controller, PM-500C is equipped with Newport Linear Actuator, PM500-1A, which is mounted to a frame. Honeywell load-cell is used to measure the force applied to the sample. A 16-bit data acquisition card (National Instruments) digitizes the analog signal from the load-cell. The instrument is controlled with an external computer through GPIB-interface and a custom programmed LabVIEW-based software. Resolution: 0.1 µm in position and 0.0001 N in force measurements.

**Fig 1.** Material testing rack. A) Newport linear actuator, PM500-1A, B) Adjustable rack, C) Changeable load cell, where indenter is attached, D) platform for measurement chamber, E) Goniometer.

Determination of Poisson’s ratio

With this equipment, the Poisson’s ratio can be optically determined. The sample is compressed with a micrometer in unconfined geometry. The lateral deformation is determined with DMC 1-CCD camera (Polaroid). CCD-camera is mounted to Olympus BH-2 microscope (Olympus) and connected to PowerMac computer. Resolution: axial 1.0 µm and lateral 1.6 µm.