Mechanics of composite sandwich structures with bioinspired core

Palmetto wood has been previously identified as a potential biological template for inspiring the development of synthetically engineered materials with hierarchical microstructures that exhibit enhanced mechanical behavior. Previously, the multi-scale mechanical behavior has been studied under quasi-static loading in order to understand the relationship between the microstructure of Palmetto wood and its mechanical behavior. In this study, the mechanical behavior of dry Palmetto wood is investigated under dynamic loading using low velocity impact. The experimental results reveal that the macrofiber concentration of the Palmetto wood plays a key role in the dynamic failure mechanisms. Under low velocity impact, the dynamic damage was found to be dominated globally by axial loading induced by bending leading to localized, shear-dominated debonding at the macrofiberporous cellulose matrix interface, as well as compressive loading induced by indentation under the projectile leading to local crushing of the porous cellulose matrix and shear cracking of the macrofibers and matrix. By increasing the macrofiber concentration, it was found that the dominant failure mechanism could be transformed from the former to the latter by increasing the energy absorbed by indentation in order to increase impact resistance. This explains why the macrofiber concentration gradually decreases radially towards the center of the wood stem, since the outer portion of the wood has a high indentation resistance while the inner portion absorbs more energy through bending. A new model was proposed for to better understand the variation in mechanical behavior with macrofiber concentration and loading rate consistent with the evolution of the observed damage mechanisms. It was found that the greatest effect of increasing loading rate and macrofiber concentration was to increase the elastic modulus by 450-600% and the yield stress associated with the pore collapse mechanism by 125-175%. There is also a coupling between the evolution of plastic strain and damage that depends more strongly on macrofiber concentration than loading rate. These two effects combine to cause a significant increase in the density of energy absorption by 75-133% with increasing macrofiber concentration and strain rate. Therefore, the structure of Palmetto wood can be used as a template to guide the development of more impact resistant polymer composites, such as inserting 12 to 20 vol.% pultruded carbon fibers into the foam core of sandwich composite structures.

Investigations were conducted on physical and mechanical properties of the biocomposite boards made from compressed oil palm fronds. The bio-composites boards consist of young, intermediate and mature fronds, which were divided to three portions respectively. They were the bottom, middle and top portions for each maturity age group of the fronds. The fronds were sliced longitudinal into the thin sheet after their skins were removed. The sheets were later compressed by running them through a flattening machine. Two types of resins namely phenol formaldehyde and urea formaldehyde were used to bind the fronds' sheets together forming parallel biocomposite board from compressed oil palm fronds. The physical and mechanical properties of this bio-composite board were later studied. The physical properties such as density and basic density were investigated. The mechanical properties such as static bending for modulus of elasticity and modulus of rupture as well as the compression strength for modulus of rupture were studied in order to investigate their strength properties in structural application. All tests were made in accordance to the International Organization for standardization (ISO) standards. The results indicate that the bio-composite boards with higher basic density possess higher bending and compression strength compares to those with lower values. The bio-composite board from bottom portion oil palm frond shows to have the higher basic density follows by the middle and top portion for each maturity age group, meanwhile matured maturity group possess the higher basic density for each portion compare to the intermediate and young maturity group. Thus, the bending and compression strength show to have higher results for bio-composite board from bottom portion and decrease for the middle and top portion for each maturity age group, while the matured maturity group possess the higher strength result for each portion follows then by intermediate and young maturity group.

RSC Advances

This review provides a comprehensive discussion on the long-term durability performance and degradation behaviour of the increasingly popular sustainable biobased composites under various aging environments.

As knowed the MDF production is a process that uses to much energy and a lot of wood. The use of these two resources combined with the increasing demand of MDF leads to an increase of the direct and indirect emissions of CO2. Combining the recyclability of thermoplastic polymers with their good mechanical properties a structural sandwich structure has been developed and characterized into a partnership between the DesignStudioFEUP and the ISPGaya. This new product – called Wood Core Plastic (WCP) - is a sandwich structure that combines a thermoplastic core, Polypropylene (PP or Polyethylene (PE), with an external wood veneer. In this particular case the study uses an external Millettia Stuhlmenii (Wengue) wood veneer. The WCP combines the tactile and visual aspect of wood laminates with a low energy production. The WCP also can contribute to a reduction of the thermoplastics into the landfills and incinerators once they can be manufactured with recycled thermoplastics. In this article we will present the WCP production method and we will present the first studies of the mechanical behaviour of WCP. We will also compare this behaviour with the veneered MDF (vMDF) behaviour for the same situation. Using the method proposed by J. Yarwood and P. Eagan, which is in use at the Minnesota Office of Environmental Assistance, we will present the study of the environmental impact of both materials (WCP and vMDF).

International Journal of Mechanical and Production Engineering Research and Development

The objective of this study is to develop a new Bio-composite material to fulfil the demand of public & minimize the use of various non-biodegradable materials to save our environment & soil. In future, Bio-composite is going to replace many materials due to its better mechanical properties. In this paper, the focus is on the use of natural and agricultural wastes, which are present in abundance in nature & whose production can also be increased as per the need. In the present study, bio composite materials were developed, in which Natural fibres i.e. Banana, Sisal, and Wheat Straw fibre were used as reinforcing materials with Epoxy resin CY-230 and Hardener HY-951. In this Study, the mechanical properties such as Flexural, Compression and Impact Strengths of the specimens with different composition were tested and compared. Fabrication of different specimens was done by using hand layout technique. Bio-composite samples were developed with different composition of constituents. Mechanical tests were conducted according to ASTM and ISO standards and their properties were analysed. It has been observed that equal weight percentage of Banana & Sisal fibers i.e. specimen E2 possess much better mechanical properties.

Composites Science and Technology, 2012

The aim of this investigation was to study a new family of wood polymer composites with thermoplastic elastomer matrix (pebax Ò copolymers) instead of commonly used WPC matrices. These copolymers are polyether-b-amide thermoplastic elastomers which present an important elongation at break and a melting point below 200°C to prevent wood fibers degradation during processing. Moreover these polymers are synthesized from renewable resources and they present a hydrophilic character which allow them to interact with wood fibers. We have used two pebax Ò grade with different hardness and three types of wood fibers, so the influence of the matrix and wood fibers characteristics were evaluated. Composites were produced using a laboratory-size twin screw extruder to obtain composite pellets prior to injection moulding into tensile test samples. We have evaluated fibers/matrix interaction by differential scanning calorimetry (DSC), infrared spectroscopy (IRTF) and scanning electron microscopy (SEM). Then, the mechanical properties, through tensile test, were assessed. We also observed fibers dispersion into the matrix by tomography X. DSC, IRTF and SEM measurements confirmed the presence of strong interface interactions between polymer and wood. These interactions lead to good mechanical properties of the composites with a reinforcement effect of wood fibers due also to a good dispersion of fibers into the matrix without agglomerate.

Journal of Applied Polymer Science, 2004

Plastic fiber composites, consisting of polypropylene (PP) or polyethylene (PE), and pinewood, big blue stem (BBS), soybean hulls, or distillers dried grain and solubles (DDGS), were prepared by extrusion. Young's modulus, tensile and flexural strengths, melt flow, shrinkage, and impact energy, with respect to the type, amount, and size of fiber on composites, were evaluated. Young's moduli under tensile load of wood, BBS, and soybean-hull fiber composites, compared with those of pure plastic controls, were either comparable or higher. Tensile strength significantly decreased for all the PP/fiber composites when compared with that of the control. Strength of BBS fiber composites was higher than or comparable to that of wood. When natural fibers were added there was a significant decrease in the melt flow index for both plastic/fiber composites. There was no significant difference in the shrinkage of all fiber/plastic composites compared to that of controls. BBS/PE plastic composites resulted in higher notched impact strength than that of wood or soybean-hull fiber composites. There was significant reduction in the unnotched impact strength compared to that of controls. BBS has the potential to be used as reinforcing materials for low-cost composites.

International Wood Products Journal, 2020

The purpose here is to study the variation in the natural frequency of a material due to damage. Also, compare the shift in Natural Frequency that of a SYP-SP (Sweet Potato) bio-composite to a commercial SYP composite. Additionally, the motivation behind the study is to eventually provide biodegradable materials, as petroleum-based products being a finite resource and having more potential to harm the environment. The researcher obtained the Natural Frequencies by Experimental modal analysis using a cantilever beam vibration technique. The shift for the first three natural frequencies for damage induced SYP-SP composite was 10%, 8.6%, and 9.5% and for SYP-Commercial composite was 7.95%, 0.7%, and 0.9% respectively. The undamaged specimens of SYP-SP bio-composite and that of a commercial SYP composite showed behaviour almost on similar lines. Thus, stating the potential use of SYP-SP bio-composite for commercial applications like wood flooring, fencing, and other related applications.

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. List of contributors xiii About the editors xix 1. An overview of mechanical and physical testing of composite materials N. Saba, M. Jawaid and M.T.H. Sultan 1.1 Introduction 1.2 Mechanical and physical testing 1.3 Physical test 1.4 Conclusions Acknowledgments References 2. Flexural behavior of textile-reinforced polymer composites Nazire Deniz Yılmaz and G.M. Arifuzzaman Khan 2.1 Introduction 2.2 Components of TRPCs 2.3 Fabrication of TRPCs 2.4 Determination of TRPC flexural performance 2.5 Modelling flexural properties of TRPCs 2.6 Conclusion References 3. Mechanical performance of natural fibersebased thermosetting composites Wafa Ouarhim, Nadia Zari, Rachid Bouhfid and Abou el kacem Qaiss 3.1 Introduction 3.2 Thermoset matrices 3.3 Natural fibersebased thermoset composites 3.4 Thermoset composites 3.5 Mechanical performance of natural fibersebased thermoset composites 3.6 Conclusion and future work Acknowledgments References 4. Dimensional stability of natural fiber-based and hybrid composites Mohamad Nurul Azman Mohammad Taib and Nurhidayatullaili Muhd Julkapli 4.1 Introduction 4.2 Factors regarding dimension stability of hybrid materials 4.3 Improvement in dimensional stability 4.4 Conclusion References 5. Tensile properties of natural and synthetic fiber-reinforced polymer composites Rozyanty Rahman and Syed Zhafer Firdaus Syed Putra 5.1 Introduction 5.2 Tensile properties 5.3 Fiber-reinforced polymer composite 5.4 Conclusions References 6. Mechanical behavior of carbon/natural fiber-based hybrid composites Hind Abdellaoui, Marya Raji, Hamid Essabir, Rachid Bouhfid and Abou el kacem Qaiss 6.1 Introduction 6.2 Physicochemical characteristics of chosen fillers 6.3 Filler preparation 6.4 Filler characterization 6.5 Nanocomposite processing techniques 6.6 Mechanical behavior of hybrid composites 6.7 Conclusion Acknowledgments References 7. Compressive and fracture toughness of natural and synthetic fiber-reinforced polymer Mustafa Abu Ghalia and Amira Abdelrasoul 7.1 Introduction 7.2 Composition and structures of natural/synthetic fibers 7.3 Mechanical properties of natural and synthetic fibers 7.4 Factors affecting the mechanical properties of natural/ synthetic fiber-reinforced polymer 7.5 The compressive response of natural and synthetic fiber-reinforced polymer 7.6 Evaluate of fracture toughness of natural/synthetic fiber-reinforced polymers 7.7 Natural/synthetic fiber-reinforced polymer: future development viii Contents 7.8 Conclusions Acknowledgments References 8. Effect of treatment on water absorption behavior of natural fiberereinforced polymer composites

Material discoveries and development have always been the cause of the growth and development of a nation and the need of naturally made materials is the need of hours. Thus this paper takes you to the development of a hybrid composite made of sisal fiber with epoxy as the matrix intertwined with softwood bio-char. Softwood chip bio-char, produced by slow pyrolysis, has a porous structure improving its nutrient absorbing capacity, surface area and thus a potential substituent. Bio-char has an appreciable carbon sequestration value i.e. a carbon absorbing product. The orientation of sisal fiber are changed and studied in longitudinal and orthogonal direction indicating superiority of longitudinal fiber orientation .It also addresses the variation in mechanical characteristic (tensile flexural and impact) with different constituent of the new composite and its position in material selection charts with a direction for further work.