Fiber-reinforced composite

A fiber-reinforced composite (FRC) is a composite building material that consists of three components: (i) the fibers as the discontinuous or dispersed phase, (ii) the matrix as the continuous phase, and (iii) the fine interphase region, also known as the interface.^[1]^[2] This is a type of advanced composite group, which makes use of rice husk, rice hull, and plastic as ingredients. This technology involves a method of refining, blending, and compounding natural fibers from cellulosic waste streams to form a high-strength fiber composite material in a polymer matrix. The designated waste or base raw materials used in this instance are those of waste thermoplastics and various categories of cellulosic waste including rice husk and saw dust.

FRC is high-performance fiber composite achieved and made possible by cross-linking cellulosic fiber molecules with resins in the FRC material matrix through a proprietary molecular re-engineering process, yielding a product of exceptional structural properties.

Through this feat of molecular re-engineering selected physical and structural properties of wood are successfully cloned and vested in the FRC product, in addition to other critical attributes to yield performance properties superior to contemporary wood.

This material, unlike other composites, can be recycled up to 20 times, allowing scrap FRC to be reused again and again.

The failure mechanisms in FRC materials include delamination, intralaminar matrix cracking, longitudinal matrix splitting, fiber/matrix debonding, fiber pull-out, and fiber fracture.^[1]

Difference between wood plastic composite and fiber-reinforced composite:

Features	Plastic lumber	Wood plastic composite	FRC	Wood
Recyclable	Yes	No	Yes	Yes
House Construction	No	No	Yes	Yes
Water Absorption	0.00%	0.8% and above	0.3% and below	10% and above

Properties

Tensile Strength	ASTM D 638	15.9 MPa
Flexural Strength	ASTM D 790	280 MPa
Flexural Modulus	ASTM D 790	1582 MPa
Failure Load	ASTM D 1761	1.5 KN - 20.8 KN
Compressive Strength		20.7MPa
Heat Reversion	BS EN 743 : 1995	0.45%
Water Absorption	ASTM D 570	0.34%
Termite Resistant	FRIM Test Method	3.6

Basic Principles

The appropriate "average" of the individual phase properties to be used in describing composite tensile behavior can be elucidated with reference to Fig. 6.2. Although

this figure illustrates a plate-like composite, the results that follow are equally applicable to fiber composites having similar phase arrangements. The two phase

material of Fig. 6.2 consists of lamellae of $\alpha$ and $\beta$ phases of thickness $l_{\alpha }$ and $l_{\beta }$ . and respectively. Thus, the volume fractions ( $V_{\alpha }$ , $V_{\beta }$ ) of the phases are $V_{\alpha }={\frac {l_{\alpha }}{l_{\alpha }+l_{\beta }}}$ and $V_{\beta }={\frac {l_{\beta }}{l_{\alpha }+l_{\beta }}}$ .

Case I: Same stress, different strain

A tensile force F is applied normal to the broad faces (dimensions Lx L) of the phases. In this arrangement the stress borne by each of the phases (= F/ $L^{2}$ ) is the same, but the strains ( $\varepsilon _{\alpha }$ , $\varepsilon _{\beta }$ ) they experience are different. composite strain is a volumetric weighted average of the strains of the individual phases.

$\vartriangle l_{\alpha }=\varepsilon _{\alpha }l_{\alpha }$ , $\vartriangle l_{\beta }=\varepsilon _{\beta }l_{\beta }$

The total elongation of the composite, $\vartriangle l_{c}$ is obtained as $\vartriangle l_{c}=N\vartriangle l_{\alpha }+N\vartriangle l_{\beta }$

and the composite strain $\varepsilon _{c}$ is, $\varepsilon _{c}$ = ${\frac {\vartriangle l_{c}}{N(l_{\alpha }+l_{\beta })}}$ = $V_{\alpha }\varepsilon _{\alpha }+V_{\beta }\varepsilon _{\beta }$ = $\sigma {\biggl (}{\frac {V_{\alpha }}{E_{\alpha }}}+{\frac {V_{\beta }}{E_{\beta }}}{\biggr )}$

Composite modulus $E_{c}={\frac {E_{\alpha }E_{\beta }}{V_{\alpha }E_{\beta }+V_{\beta }E_{\alpha }}}$

Case II: different stress, same strain

Fibers that are aligned parallel to the tensile axis, the strains in both phases are equal (and the same as the composite strain), but the external force is partitioned

unequally between the phases. $F=F_{\alpha }+F_{\beta }=NL(\sigma _{\alpha }l_{\alpha }+\sigma _{\beta }l_{\beta })$

$\sigma _{c}=\left({\frac {\sigma _{\alpha }l_{\alpha }}{l_{\alpha }+l_{\beta }}}+{\frac {\sigma _{\beta }l_{\beta }}{l_{\alpha }+l_{\beta }}}\right)=\sigma _{\alpha }V_{\alpha }+\sigma _{\beta }V_{\beta }$

$E_{c}=V_{\alpha }E_{\alpha }+V_{\beta }E_{\beta }$

Deformation behavior

When the fiber is aligned parallel to the direction of the matrix and applied the load as the same strain case. The fiber and matrix has the volume fraction $V_{f}$ , $V_{m}$ ; stress $\sigma _{f}$ , $\sigma _{m}$ ; strain $\varepsilon_f$ , $\varepsilon _{m}$ ; and modulus $E_{f}$ , $E_{m}$ . And here $\varepsilon_f$ = $\varepsilon_f$ = $\varepsilon _{c}$ . The uniaxial stress-strain response of a fiber composite can be divided into several stages.

In stage 1, when the fiber and matrix both deform elastically, the stress and strain relation is $\sigma _{c}=V_{f}E_{f}\varepsilon _{f}+V_{m}E_{m}\varepsilon _{m}=\varepsilon _{c}(V_{f}E_{f}+V_{m}E_{m})$

$E_{c}=V_{f}E_{f}+V_{m}E_{m}$

In stage 2, when the stress for the fiber is bigger than the yield stress, the matrix starts to deform plastically, and the fiber are still elastic, the stress and strain relation is

$\sigma _{c}=V_{f}E_{f}\varepsilon _{f}+V_{m}\sigma _{m}(\varepsilon _{m})=V_{f}E_{f}\varepsilon _{c}+V_{m}\sigma _{m}(\varepsilon _{c})$

$E_{c}=V_{f}E_{f}+V_{m}({\frac {d\sigma _{m}}{d\varepsilon _{c}}})$

In stage 3, when the matrix the fiber both deform plastically, the stress and strain relation is

$\sigma _{c}=V_{f}\sigma _{f}(\varepsilon _{f})+V_{m}\sigma _{m}(\varepsilon _{m})=V_{f}\sigma _{f}(\varepsilon _{c})+V_{m}\sigma _{m}(\varepsilon _{c})$

$E_{c}=V_{f}({\frac {d\sigma _{f}}{d\varepsilon _{c}}})+V_{m}({\frac {d\sigma _{m}}{d\varepsilon _{c}}})$

Since some fibers do not deform permanently prior to fracture, stage 3 cannot be observed in some composite.

In stage 4, when the fiber has already become fracture and matrix still deforms plastically, the stress and strain relation is

$\sigma _{c}=V_{m}\sigma _{m}(\varepsilon _{m})$

However, it is not completely true, since the failure fibers can still carry some load.

Application

There are also applications in the market, which utilize only waste materials. Its most widespread use is in outdoor deck floors, but it is also used for railings, fences, landscaping timbers, cladding and siding, park benches, molding and trim, window and door frames, and indoor furniture. See for example the work of Waste for Life, which collaborates with garbage scavenging cooperatives to create fiber-reinforced building materials and domestic problems from the waste their members collect: Homepage of Waste for Life

References

1 2 WJ Cantwell, J Morton (1991). "The impact resistance of composite materials -- a review". Composites. 22 (5): 347–62. doi:10.1016/0010-4361(91)90549-V.
↑ Serope Kalpakjian, Steven R Schmid. "Manufacturing Engineering and Technology". International edition. 4th Ed. Prentice Hall, Inc. 2001. ISBN 0-13-017440-8.

3. Thomas H. Courtney. "Mechanical Behavior of Materials". 2nd Ed. Waveland Press, Inc. 2005. ISBN 1-57766-425-6

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

Fiber-reinforced composite

Properties

Basic Principles

Deformation behavior

Application

See also

References