Embedment Properties: 

The embedment characteristics of the wood medium around a fastener must be obtained by a test in which the medium is uniformly pressed. Normally this is not possible, as the fastener would also bend. The program HYST has been used within a material characterization program (EMFIT) to extract the embedment characteristics. The first of the following figures shows an experimental force/displacement curve and the second the fit obtained using HYST with the identified embedment parameters.  

The form of the embedment equation is as implemented in HYST. 

A comprehensive testing program has been completed to catalogue embedment characteristics for two types of nails (spiral, Common) and different combinations of lumber (SPF, Hemlock, Douglas fir) and Oriented Strand Board, Plywood and Gypsum boards.

Additional information on EMFIT can be found in:
Foschi, R.O., Yao, F., and Rogerson, D. 2000. "Determining Embedment Response Parameters from Connector Tests ", Proceedings, World Timber Engineering Conference, Whistler, B.C. Canada, July 31-August 4, 2000.