Issue 35

T. Haiyan, Frattura ed Integrità Strutturale, 35 (2016) 472-480; DOI: 10.3221/IGF-ESIS.35.53 477 C C f f m m A A A      (3) Figure 4 :  -  curves. Both sides of Eq. (2) are divided by A c , and then we get: C f f m m V V      (4) Strain is the same when bamboo is under stress. C f m      (5) If we divide Eq. (2) with ε c A c , we get: f f C C m m C C C C C C A A A A A A         (6) When load is within linear strain range, then correlation of elastic modulus E c with elastic modulus and volume modulus of different element can be obtained. (1 ) C f f m m f f m f E E V E V E V E V      (7) Eq. (3) and (6) can be called as mixture law for mesomechanics of composite materials [18]. Experiment and results The samples were placed in self-tightening fixture of microcomputer controlled mechanical machine and the test section of samples was installed with extensometer whose gauge length is 50 mm. Then the force was loaded in a speed of 2 mm/min until fracture emerges. As ground tissue of bamboo, it has higher strength and modulus than bamboo fibre bundle, thus mechanical behavior of bamboo samples in tensile test is mainly determined by strength and rigidity of bamboo fiber bundle. Corresponding stress-strain curve (Fig. 4) shows up little or no non-linear deformation. Small pieces cut from the position close to fracture was first placed into oven after being added with solution containing 10% glacial acetic acid and 10% hydrogen peroxide and then soaked for 2 or 3 days at 60 °C. Afterwards, it was cut into section in a thickness of 15 μm after being softened by alternated cooling and