Lazzeri and Bucknall (17) introduced a model for internal cavitation of rubber particles, based on an energy balance between the volumetric strain
energy released during cavitation and the surface energy associated with the generation of a new surface, plus the energy needed to stretch the rubber around the void.
As the concrete softened, the volumetric strain
reached zero marking the transfer of load from concrete core to the FRP confinement.
A delayed damage due to confining pressure of maximum value is reached at zero volumetric strain
Using the true stress-strain curve and the volumetric strain
response as the main targets the identification of the four variables [[sigma].
Modeling the evolution of the positive volumetric strain
associated to this second mechanism is out of the scope of this article.
To estimate mechanical properties and volumetric strain
by means of the uniaxial tensile test, the dumbbell specimens were molded under the same molding conditions as shown in Fig.
In order to evaluate mechanical properties and volumetric strain
by means of the uniaxial tensile test, the dumbbell specimens, each of whose thickness is 2 mm, width is 10 mm, and length is 50 mm in its parallel portion, were molded under the same molding conditions.
Next, also based on the temperature information, the volumetric strain
is determined for each point in time and space.
first increases for a short time after the strain ceases, and then subsequently decreases .
The constitutive model is expressed in terms of modulus, which is a function of strain rate and volumetric strain
The linear strain is one third of the volumetric strain
and the net linear strain as a function of depth has been calculated by subtracting the value of [[Epsilon].
Alpha]] = Volumetric strain
due to temperature change.