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Technique to Study Crack Propagation in Free Standing Biaxially Strained Films by Determining the Displacement Under an Orthogonally Applied Point Load to Measure the Stress, While Simultaneously Observing a Crack Front

IP.com Disclosure Number: IPCOM000109651D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Geldermans, P: AUTHOR [+2]

Abstract

Disclosed is a technique for the determination of the fracture toughness in free-standing biaxially strained films.

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This is the abbreviated version, containing approximately 80% of the total text.

Technique to Study Crack Propagation in Free Standing Biaxially Strained Films by Determining the Displacement Under an Orthogonally Applied Point Load to Measure the Stress, While Simultaneously Observing a Crack Front

       Disclosed is a technique for the determination of the
fracture toughness in free-standing biaxially strained films.

      The method consists of the application of a continuously
increasing biaxial strain in a free-standing film in which a small
slit is made, to act as the beginning of a growing crack.  While the
strain is increased, the onset and progress of crack propagation is
observed at the tip of the slit.  Simultaneously, the stress in the
film is monitored by measuring its compliance under a vertical point
load.

      The biaxial strain in the film is introduced by either of two
methods: the first one uses an 8-segmented ring to which the film is
attached.  The individual segments of the ring are attached to
slides; moving the slides outward introduces strain in the film (Fig.
1).

      The second method uses the "double ring" technique.  The film
is attached to an outer ring.  A second, smaller ring is placed under
the film and pushed up into the film (Fig. 2).  When both rings are
concentric, the change in geometry of the film results in a uniform
biaxial strain.

      The stress in the film is determined by measuring the
compliance of the film under a vertical point load (Figs. 3 and 4).
This method of measuri...