Landing gear dynamic tests with strain gages

Strain gage sensing is widely used method for measurements conducted during dynamic tests. This article describes electrical resistance strain gages performing force measurement during the tests of main and nose landing gear of medium-lift civil aircraft. It is the most common method used for measuring mechanical properties like force, pressure, stress, strain, etc. Strain gages were installed in selected areas of the Drop Test Stand. The paper presents advantages of strain gage measuring method in regards to commercially available, ready-made force sensors. Furthermore, it describes the process of selecting strain gage and load cell measurement systems (bridge, half bridge, quarter bridge) and its influence on the test results. What is more the technological process is presented, taking into account the strain gage installation adhesive technology and sensor protection against external conditions, performance of the measurement system and connection to the data acquisition system. Continuing with the process description of calibrating a load cell system for measuring the occurring forces. The article is summed up with an analysis of the problems which arise during the installation and measurement process using strain gages, and includes a description of advantages and disadvantages that occur while applying strain gages while preforming force measurement.