по смыслу упругая деформация - это проявление податливости, наверно лучше написать в общем виде: изменение податливости?

Recording—Record force versus head displacement
and force versus LVDT/compressometer deflection data
continuously, or at frequent regular intervals; for this test
method, a sampling rate of 2 to 3 data recordings per second,
and a target minimum of 100 data points per test are recommended.
If a compliance change or initial failures are noted,
record the force, displacement, and mode of damage at such
points. Record the maximum force, the failure force, the head
displacement and the LVDT/compressometer deflection at, or
as near as possible to, the moment of failure. Also record the
force and head displacement at 2 % deflection, if that deflection
level is achieved prior to failure.

вопрос по слову core
в сэндвич структурах как правильно - сердечник (сердцевина) или заполнитель? в описаниях есть и то, и др.
Есть (из другого текста) явное разделение на заполнитель и сердцевину:

This guide establishes the essential and desirable elements of data required for the identification in computerized material property databases of fibers, fillers, and core materials used in composite materials. A recommended format for entry of these fields into a computerized database is provided. Examples of the application of this guide are also included.