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| Version | Summary | Created by | Modification | Content Size | Created at | Operation |
|---|---|---|---|---|---|---|
| 1 | Raphael Olabanji Ogunleye | + 3755 word(s) | 3755 | 2021-12-27 03:50:20 | | | |
| 2 | Peter Tang | Meta information modification | 3755 | 2022-01-06 06:52:34 | | | | |
| 3 | Lindsay Dong | Meta information modification | 3755 | 2022-03-28 07:17:55 | | |
Composite materials are developed by combining materials offering unique properties that cannot be achieved individually by the constituent materials. To produce a fibre-reinforced polymer composite, fibres of various configurations and stiffness are embedded into a polymer matrix of lower stiffness. While the fibre is responsible for carrying the load and offering much needed strength and stiffness, the polymer matrix is responsible for the mobility of the load to other parts of the fibre by providing the required binding forces. The matrices also prevent the reinforced fibres from absorbing moisture, propagating micro-cracking due to microbial and chemical attacks.

|
Fibre |
Density (kg/m3) |
Tensile Strength (MPa) |
Elongation at Break (%) |
Young Modulus (GPa) |
References |
|
|---|---|---|---|---|---|---|
|
Natural fibres |
Kenaf |
1200 |
295–930 |
2.7–6.9 |
53 |
|
|
Sisal |
1200 |
507–885 |
1.9–3 |
9.4–22 |
||
|
Flax |
1380 |
343–1035 |
1.2–3 |
27.6 |
||
|
Bamboo |
800–1400 |
391–1000 |
2 |
11–30 |
||
|
Banana |
1350 |
529–914 |
3–10 |
8–32 |
||
|
Wheat straw |
1600 |
273 |
2.7 |
4.76–6.58 |
||
|
Hemp |
1350 |
580–1110 |
1.6–4.5 |
70 |
||
|
Jute |
1230 |
187–773 |
1.5–3.1 |
13–26.5 |
||
|
Ramie |
1440 |
400–938 |
2–4 |
61.4–128 |
||
|
Rice straw |
1650 |
449 |
2.2 |
1.21–1.25 |
||
|
Synthetic fibres |
E-glass |
2500 |
2000–3000 |
2.5 |
70 |
[36] |
|
Carbon |
1800 |
4000 |
1.3 |
300 |
[37] |
|
|
Kevlar |
1400 |
3600 |
2.7 |
130 |
[37] |
|
|
Nylon |
1100 |
950 |
18 |
5 |
[37] |
|
Material |
Prestress Technique |
Research Area |
Results of Findings |
References |
|---|---|---|---|---|
|
Glass fibre woven into a fabric Phenol-based formaldehyde resin |
Elastically prestressing of the glass fibre using tensioning rod (EPPMC). |
Assessment of the compressive and tension characteristics of the composite. |
Enhancement of elastic properties up to 31% was recorded due to the straightening of the warp fibres. |
[38] |
|
Unidirectional graphite/epoxy prepreg tape |
Prepreg tape was subjected to tension by bending over a steel roller (EPPMC). |
Tensile and elastic modulus measurement |
Up to 17% increase in tensile strength Composite elastic modulus was not affected |
[39] |
|
Unidirectional carbon fibre/epoxy composite with 60% fibre volume fraction |
The load was applied to fibre before curing but the nature of assembly was not reported (EPPMC). |
Thermal stress analysis of the composite. |
Fibre-prestresses lessen the residual stresses in the matrix. |
[40] |
|
Unidirectional E-glass fibre/polyester resin with 56% fibre volume fraction |
Deadweight (EPPMC) |
Tensile properties evaluation |
The tensile strength increases with an increase in the level of prestressing (60–80 MPa applied load). The maximum percentage increase in tensile strength and modulus obtained were 15% and 18%, respectively. |
[41] |
|
Carbon fibre/epoxy resin cross-ply laminate with 70% fibre volume fraction |
Filament winding (EPPMC) |
Modelling and experimental study of composite failure |
Failure strength of the ply increased by increasing the prestress level up to 690 MPa |
[42] |
|
Graphite fibre/epoxy resin, unsymmetric cross-ply laminate with 56% fibre volume fraction |
Hydraulic cylinder (EPPMC) |
Examination of the tensile strength, curvature and transverse cracking |
Fibre-prestressing reduced warping, curvature and transverse crack. Up to 28% increase ultimate strength |
[31] |
|
Unidirectional Nylon 6.6 fibre/polyester resin (up 3% fibre volume fraction) |
Bespoke vertical stretching rig (VPPMC) |
Analysis of the impact energy |
Viscoelastically induced compressive stresses. Absorption of higher impact energy (25%) by the prestressed sample |
[43] |
|
E-glass fibre/epoxy resin cross-ply laminate (56% fibre volume fraction) |
Biaxial loading frame (EPPMC) |
Effect of low-velocity impact performance |
25% increase in impact performance at low velocity due to prestressing |
[44] |
|
E-glass fibre/epoxy resin cross ply laminate (56% fibre volume fraction) |
Biaxial loading frame (EPPMC) |
Effect of high- and low-velocity impact performance |
Improvement of impact performance at a low-level velocity |
[45] |
|
Unidirectional E-glass fibre/epoxy cross-ply laminates (58.2% fibre volume fraction) |
Flatbed (EPPMC) |
Tensile, fatigue life and compressive strength measurement |
Improved fibre alignment, increase in resistance to onset damage due to induced compressive strength. 9% increase in tensile modulus and compressive strength at prestressing levels of 51 MPa and 80 MPa, respectively. |
[46] |
|
Unidirectional Nylon 6.6 fibre/epoxy resin (16, 28, 41) and 53% fibre volume fraction |
Bespoke vertical stretching rig |
Tensile strength and modulus measurement |
30% and 15% tensile modulus and tensile strength, respectively. |
[47] |
|
Carbon and glass fibre/Hexcel cross-ply laminates |
Flatbed (EPPMC) |
Experimental and finite element analysis of bistable prestressed buckled laminate |
Induction of bistable behaviour through prestressing. |
[48] |
|
Unidirectional Nylon 6.6 fibre/polyester resin (8, 12, 16% fibre volume fraction) |
Bespoke vertical stretching rig (VPPMC) |
Flexural properties measurement |
Up to 50% increase in flexural modulus. |
[49] |
|
Unidirectional S-glass fibre/composite resins (Quixfil and Adoro) (12% fibre volume fraction) |
Deadweight (EPPMC) |
Flexural properties measurement |
Increase in flexural strength. |
[50] |
|
Unidirectional UHMWPE fibre/polyester resin (3.6% fibre volume fraction) |
Bespoke vertical stretching rig (VPPMC) |
Impact properties measurement |
Prestressing increases impact energy absorption (up to 40% increase in some batches). |
[30] |
|
Carbon fibre/epoxy resin (50% fibre volume fraction) |
Deadweight (EPPMC) |
Impact properties |
Increase in strength of composite material. |
[51] |
|
Hybrid unidirectional Nylon 6.6 and Kevlar fibres/polyester |
Bespoke vertical stretching rig (for Nylon alone) (VPPMC) |
Impact and flexural test |
33 and 40% rise in absorption energy and flexural modulus. |
[30] |
|
Unidirectional Nylon 6.6 fibre/polymer resin (fibre volume fraction 2.2%) |
Bespoke vertical stretching rig (VPPMC) |
Impact assessment |
Impact energy absorbed increased (40%). |
[52] |
|
Flax yarn/polyester resin |
Tension frame (EPPMC) |
Tensile and flexural assessment |
Fibre alignment enhancement. Increased tensile strength and modulus. Increase in flexural strength and modulus. |
[26] |
|
Plain weave E-glass fabric/polyester resin (16% fibre weight fraction) |
Hydraulic cylinder biaxial loading frame (EPPMC) |
Flexural characteristics |
Up to 16% increase in flexural strength at 50 MPa optimum prestressing level |
[53] |
|
Plain weave E-glass fabric/polyester resin (11% fibre weight fraction) |
Hydraulic cylinder biaxial loading frame (EPPMC) |
Tensile and fatigue characteristics |
Fatigue life increased up to 43% Fatigue life improvement when under low and intermediate stress fatigue load |
[54] |
|
Unidirectional E-glass fibre mats/epoxy resin |
Horizontal testing machine (EPPMC) |
Flexural, tensile and compression properties |
Reduction in fibre waviness Increase in flexural, tensile and compressive strength |
[8] |
|
Nylon 6.6 yarn/polyester cross-ply composite |
Bespoke stretching rig (VPPMC) |
Impact behaviour |
Up to 29% reduction in damage depth |
[28] |
|
Unidirectional E-glass fibre/epoxy resin (10% fibre volume fraction) |
Deadweight method (EPPMC) |
Tensile properties |
Increase in maximum strength, percentage elongation and rupture strength by 38.5%, 45.57% and 106.2%, respectively |
[55] |
|
Destructive Testing (DT) |
Non-Destructive Testing (NDT) |
|---|---|
|
Part of the materials is removed or damaged. |
Testing can be done without removing or damaging the material. |
|
Testing cannot be repeated on the same specimen. |
Testing can be repeated on the same specimen. |
|
Residual stress measurement is limited to a small area of the material sample. |
Residual stresses can be measured within a large surface (e.g., laminate). |
|
Global residual stresses distribution along the plies in a composite can be measured. |
They cannot estimate global residual stress distributions along with composite plies. |
|
Methods |
Principle |
Material |
Shortcomings |
References |
|---|---|---|---|---|
|
Layer Removal (DT) |
It monitors the elastic response of a laminate to the release of residual stresses |
Ceramics Metals Polymers Composites |
Additional stresses can be imparted to the test sample due to the machining of the composite surfaces. Limited to macro-scale residual stresses |
|
|
Hole drilling (SDT) |
Drilling of a hole into the stressed object releases the stresses, leading to changes in the surrounding strain field that may be measured and related to the relaxed stresses. |
Ceramics Metals Polymers Composites |
It requires several assumptions to simplify the result solution. Accurate measurement around the hole, especially in the fibre direction, is very challenging. Limited to macro-scale residual stress measurement |
|
|
Ring-Core Method (SDT) |
It follows a principle comparable to the hole-drilling method. However, instead of discharging residual stresses by drilling a hole and measuring the elastic reaction of the surrounding material, the ring-core method discharges stress by cutting an annular groove into the surface of a component that contains residual stress. |
Metals Ceramics Polymers |
Limited to homogenous and isotropic material. |
[67] |
|
Contour Method (DT) |
The material is sliced through by a planar surface, releasing residual stresses across the plane. As a result, the surface experiences out-of-plane deformation, which is recorded, and the underlying residual stresses across the cut are calculated using the finite element technique. |
Ceramics Metals Plastics Composites |
Difficulty in measuring residual stresses close to the surface of the material. Not suited for small components. |
[68] |
|
Slitting Method (DT) |
A tiny slit is cut into a prestressed sample, and the resultant deformation parallel to the slot’s direction induced by the restoration of force equilibrium is determined. The repetition of this procedure at increasing depths allows for the determination of residual stress across the component’s thickness. |
Ceramics Metals Plastics Composites |
Macro-scale residual stresses cannot be fully measured. Only average stress along the transverse direction (y-axis) can be measured. |
[69] |
|
Neutron Diffraction Method (NDT) |
Raman spectroscopy employs light scattering to measure the vibrational energy of crystalline chemical bonds. The dispersed light is detected, and typical Raman peaks may be detected. Any externally imposed strain alters the position of these peaks. Consequently, a stressed and unstressed sample’s Raman peak position variations may be used to calculate the applied strain. |
Metal Ceramics Composites |
Resolution is limited, and residual stress changes smaller than 1 mm cannot be measured. Not suitable for amorphous materials |
[70] |
|
Raman Spectroscopy Method (NDT) |
Stresses are determined by monitoring the frequency of certain luminescence peaks in comparison to those in an unstressed state. |
Ceramics Polymers Composites |
Limited to macro-scale residual stresses measurement. |
[71] |
|
X-ray Diffraction Method (NDT) (destructive if used for measuring depth) |
When residual stress is determined using X-ray diffraction (XRD), the strain in the crystal lattice is determined and the related residual stress is calculated using the elastic constants, assuming that the relevant crystal lattice plane exhibits linear elastic deformation. |
Metal Ceramics Composites |
Applicable to polycrystalline materials only. The accuracy of this method is affected by the texture and grain size. Measurement is limited to the surface of the material |
[72] |
|
Synchrotron X-ray Method (NDT) |
Similar to the X-ray diffraction method. However, X-rays are far more intense and have a much greater energy, and their tremendous energy allows them to penetrate much farther into materials. |
Metal Ceramics Composites |
Applicable to polycrystalline materials only |
[73] |
|
Ultrasonic Method (NDT) |
The material is subjected to an ultrasonic (acoustic) wave, which is then detected by reflection, transmission or scattering. To determine the magnitude of stresses, the velocity of an ultrasonic wave in some modes is evaluated. |
Metals Ceramics Composites |
Not suitable for amorphous materials. Limited to macro-scale residual stress measurement. |
[74] |
DT: Destructive testing, SDT: Semi-destructive testing, NDT: Non-destructive testing.