Probe for measurement of strains inside solid bodies

Trees develop high residual stresses in their stems so they can bend in the wind without being damaged. Crosscutting the stem into short cylindrical sections relieves and redistributes the residual stresses. A probe was built to measure the stress distribution near the section ends. It consists of a tube holding a series of 12 strain-gage clips which register the diametrical changes of a drillhole as the stresses are relieved by sawing the stem into short sections.