Prediction of the transverse tensile strength

The transverse tensile strength is a main evaluating indicator for NASC in engineering, and its prediction may be performed according to 3 cases, as follows.

1. Debonding of interface from fiber

Prediction of the transverse tensile strength Подпись: nVf TT + 2 К f aT Подпись: _ _ t: +rf 1 - 2-І—L Подпись: mH Подпись: (35)

In this case, the transverse tensile strength can be calculated by

Prediction of the transverse tensile strength Подпись: ' f32 fi ffVf a{ Подпись: _ _ t: + rf 1 - 2-1—L Подпись: (36)

Eq. (35) can be used to predict the transverse tensile strength assuming that all fibers orientate in the same direction at the moment the matrix debonds from the fibers. If the fibers orientate in different directions, some will bear the longitudinal load. In this case, the transverse tensile strength is larger than that calculated by Eq. (35), and it can be calculated by Eq. (36).

2. Debonding of interface from matrix

Prediction of the transverse tensile strength Подпись: 1 - 2 к+л. If Подпись: mH Подпись: (37)

If all fibers orientate in the same direction at the moment the interface debonds from the matrix, the transverse tensile strength can be calculated by Eq. (37).

Подпись: °cH fB 3~ Подпись: nVf T im + f3 2 fіffVf af + Подпись: mH Подпись: (38)

If fibers orientate in different directions, стJH can be calculated by Eq. (38).

3. Damage of interface

Prediction of the transverse tensile strength Подпись: 1 - 2 t+L If Подпись: mH Подпись: (39)

The transverse tensile strength can be calculated by

Prediction of the transverse tensile strength Подпись: ' f3 2 f іf fVf af Подпись: mH Подпись: (40)

Using Eq. (39), the transverse tensile strength can be predicted assuming that all fibers orientate in the same direction at the moment the interface is damaged. If fibers orientate in different directions, can be calculated by Eq. (40).

Prediction of the transverse tensile strength Подпись: (41)

16) is established to derive the compression-creep constitutive equation of NASC with the assumption L~Z. The cell model is divided into three parts along compression-resilience direction; the first part consists of matrix, interface and fiber (0-1), the second part consists of matrix and interface (1-2), and the third part includes only matrix (2-3).

Prediction of the transverse tensile strength

The compressive stress and strain of material relate to time. The compression-creep constitutive equation of NASC is in the form

Подпись: Rc = Prediction of the transverse tensile strength Подпись: (43)

The compression rate of NASC can be calculated by

Prediction of the transverse tensile strength Подпись: (44a)

Substituting AT=0 into Eq. (43) gives the compressive rate of NASC at room temperature. The compressive strain can be calculated by

Prediction of the transverse tensile strength Prediction of the transverse tensile strength
Подпись: (46)
Подпись: (45)

where

Substituting AT=0 into Eq. (46) gives the resilient rate of NASC at room temperature.