Advances in Chemistry and Materials Science
Volume 2 | Issue 1 | Pages 01-07
Ansys modeling for estimation Tensile and flexural strength of green composite
Ali I. Al-Mosawi 1*, Shaymaa Abbas Abdulsada 2 , Muslim M. Ali 3
1 Free Consultation, Babylon, IRAQ.
2 University of Kufa, Collage of Engineering, Materials Department, IRAQ.
3 University of Missouri, Columbia, USA.
Ansys program version (11) was used to estimation tensile and flexural strength of green composite consists of polyhydroxyalkanoate and Ramie fibers with (20,40%, and 60) wt.% reinforcement under variation loading. Specification standard of ISO-R-527 and ASTM D790 were used to modeling the tensile and flexural test samples respectively by Ansys program. Theoretical results obtained showed that the tensile and flexural strength value of polyhydroxyalkanoate increases with the addition of Ramie fibers, and this strength will increase with increasing weight fracture of fibers, and this increment due to high elastic modulus for these fibers and this strength will increase with increasing percentage of fibers and this agree with the experimental results obtained from tensile test.
Keywords: Green composite, Ansys program, Tensile and flexural strength
The use of renewable resources in recent years the main reason is to reduce dependence on petrochemicals and minerals, resulting in reducing the depletion of natural resources.And an example of renewable resources are green composites. Commercial products and applications have been developed for these green composites. Green composites which defined as biopolymers or bio-derived polymers reinforced with natural fibres, are regularly referred to as having potential uses in the automotive and construction sector .
Composite materials industry began a simple form since centuries ago, where the Babylonians used in the construction of their homes by mixing sawdust with clay to strengthen it . Composite material made from the integration of two materials or more and include blends and plastic which various in mechanical and physical properties . The merge process lead to get new material with geometric and physical properties different from the properties of materials used in the composition . General use of composites highly depends on mechanical and physical properties of these materials, so the study of these properties under the influence of forces and loads in different conditions is of great importance to determine the suitability of these properties to work place of these materials . In nature there are many examples of composite materials such as cellulose fibers material with wood, while in the industry, reinforced by synthesis fibers are the most prevalent . For the manufacture of a composites must provide two materials: (1) Matrix materials, which can be either metallic; ceramic; or polymeric materials . Polymeric materials are the most commonly used due to its good properties associated with light weight, and examples of polymeric materials epoxy, phenol, polyester and natural resins .
(2) Reinforcing Material: Must be availability two features in these materials, a high resistance and low ductility so that it can reinforced matrix material .
The aim of fibers reinforcement is to enhance the properties of resins such as tensile strength, impact strength, hardness, compression strength etc. which will give these materials for use in heavy industrial applications . These materials are called advanced composites so as to be differentiated from filled polymeric materials . The fibers in this type of composites is the main responsible for carrying external loads, and more common types are glass fibers, carbon fibers, Kevlar fibers and plant fibers (Ramie, bamboo, hemp, ramie, et) . Properties of Ramie fibers were shown in Table.1.
Table.1: Properties of Ramie fibers 
|Tensile Strength (Mpa)||Stiffness (KN/mm2)||Elongation at Break (%)||Density (g/cm3)||Moist Absorption (%)|
Tensile strength: Tensile strength is a measure of the material ability to resist static force that is trying to pull the material and broken. Fibrous composites consist of a strong brittle fiber immersed in the resinous matrix. Initially, the composite material will be started in elongated in a linear mode as a response to subject stress and with continued loading gets deviation as a result of the arrival of material to yield point, while the fibers will continue in elongate and resistance until the collapse resistance. When crushed matrix composite materials fail entirely .
Tensile strength can be obtaining from the following formula:
σ = tensile strength (N/m2)
P = test load (N)
A = cross section area of sample (m2)
Flexural strength: The test beam is under compressive stress at the concave surface and tensile stress at the convex surface . Flexural strength can be obtaining from the following formula:
F = Maximum load (N)
S = Distance between loading points (mm)
b = Sample width (mm)
t = Sample thickness (mm)
Table .2 : Specifications used to draw test samples
|Nodes No.||Element No.||Type of Element||Model||Sample|
Solid 185 Geometry
Solid 185 Geometry
Results & Discussion
Tensile strength of Biopolymer Polyhydroxyalkanoate resin before reinforcement was shown in Fig.1, where we observed that , low tensile strength for this resin when exposed to loads , because of in general the resins considered a brittle materials , which accepted with experimental results obtained by .After reinforcing by fibers this property will be improved greatly as shown in Fig.2 which represent the tensile strength to Polyhydroxyalkanoate after reinforcing with (20%) Ramie fibers , where the strength of resin will increased due to the fibers will withstand the maximum part of loads. The tensile strength will be increased as the fibers percentage addition increased as illustrated in Fig.3 and Fig.4 which represent tensile strength to Polyhydroxyalkanoate after reinforcing with (40%) and (60%) from Ramie fibers respectively. These fibers will be distributed on large area in the resin which will be improved tensile strength greatly. Flexural Strength: as mentioned above, the Biopolymer is brittle, therefore its flexural strength is low before reinforcement as shown in Fig .5. In the same behavior, flexural strength will also increase and the reason for this is that fibers will bear most of load. This situation increases with increase in the proportion of fiber’s added as in Fig.6, Fig.7 and Fig.8.
Figure1. Tensile strength to polyhydroxyalkanoate before reinforcement
Figure2. Tensile strength to polyhydroxyalkanoate after reinforcing with 20wt.% flax fibers
Figure3. Tensile strength to polyhydroxyalkanoate after reinforcing with 40wt.% flax fibers
Figure4. Tensile strength to polyhydroxyalkanoate after reinforcing with 60wt.% flax fibers
Figure5. Flexural strength to polyhydroxyalkanoate before reinforcement
Figure6. Flexural strength to polyhydroxyalkanoate after reinforcing with 20wt.% flax fibers
Figure7. Flexural strength to polyhydroxyalkanoate after reinforcing with 40wt.% flax fibers
Figure8. Flexural strength to polyhydroxyalkanoate after reinforcing with 60wt.% flax fibers
From the analytical procedure we get that, the properties of polyhydroxyalkanoate were enhanced after reinforced it by Ramie fibers. And the proportion of this improvement in properties associated with fiber’s addition, where the higher wt.% of fibers will improve properties.
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