numerical analysis of bamboo

7/28/2019 Numerical Analysis of Bamboo

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Numerical Analysis of Bamboo and Laminated Bamboo Strip Lumber(LBSL)

Researcher: Wan Tarmeze Wan AriffinSupervisors:Dr GH Little & Prof A H ChanDuration: March 2002-March 2005Sponsor: Government of Malaysia

BackgroundINBAR (the International Network for Bamboo and Rattan) in its recent publication(Ganapathy et.al 1999) reports that there have been not less than 28 types of bamboocomposites lumber (BCL), also known as bamboo panel products, developed by researchersin China and in other bamboo growing countries such as India, Indonesia, J apan, Laos,Malaysia, the Philippines, Taiwan, Thailand, Vietnam and Costa Rica. BCL have beensuccessfully used as materials for furniture making and for non structural (non-load bearing)members in construction industries. Some have proven to be comparable if not better than

wood in certain usages. For instance, the bamboo strip board (BSB), a strong and stiffmaterial has already had an economic success in China for making platforms (floors) fortransport vehicles such as trucks, buses and rail coaches, and for making concrete formworks(in building industries). Another well-known usage of BCL is in the flooring industry.Laminated bamboo floor board has been regarded as a high value flooring material withproperties better than that of wood floor board. To date, bamboo composite has not yet beenused as load bearing structural members, i.e., in the building industry. However, manybamboo scientists and engineers around the world are eyeing at this possibility as manifestedin the works by Bai et al (1999), J anssen (1981), Lee et al (1996, 1998, 1997), Mansur (2000)and Nareswoho (2000). To use bamboo effectively in building industry also means to reducethe use of timber. This, in turn, will help the world lifting the burden on the environment due toexcessive logging, especially of the diminishing tropical forests. With this aim, bambooscientists and engineers are striving to generate deeper knowledge on bamboo and better

technology of manufacturing bamboo composite beams.Statements of Research ProblemsLaminated bamboo floor board could be further developed into planks and beam (LaminatedBamboo Strip Lumber) for load bearing structural uses. The effects of bamboo materialproperties and arrangements (orientation) in the composite system on the strength andstiffness behaviour of the structural BCL have been studied through physical testings, but notfully discussed in engineering manner. Thus, the essence of this PhD work is to model theeffects through engineering analytical tools (i.e., Finite Element Analysis).The parameters that affect the strength and stiffness of LBSL are:

presence of voids glue imperfections orientation of bamboo material

Finite element models could be developed to study the effects of the parameters on thestrength and stiffness of LBSL beams and bamboo reinforced timber beam, i.e.,

FE model of bamboo strip FE model of LBSL with different arrangement/orientation of bamboo material FE model of voids in the composite system FE model of non-glued surfaces in the composite system

and, in a case of shorter and deep LBSL beam,
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FE model of shear failureFurthermore, non-linear finite element analysis would also be included to study the plasticbending behaviour of bamboo strip and LBSL beam.Mechanical Properties of Bamboo StripKnowledge on mechanical properties of bamboo in strip forms (strip or strand) is veryimportant because LBSL contains bamboo in these forms. Studies on the anatomy of bamboointernode cross-section have revealed that the strength properties change (increase) frominner to outer layer of the culm.

Figure 1 Anatomical Features of Bamboo Internode

These microstructure features cause bamboo split to behave differently under differentbending modes, i.e, a) with load on top of outer layer, b) on top of inner layer and c) on side.

Figure 2 Different Type of Loading for Bending TestThus, it is envisaged that orientation of bamboo strips in LBSL would affect the strength


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behaviour of the bamboo composite. Numerical modelling on the strip would be used as a toolto study the effects.

Modelling o f Bamboo StripThere are several approaches to model bamboo strips.1) Morphological-BasedIn this approach, the parameters of the model are based on physical properties of thematerial's microstructure. In the case of bamboo strip, it could be modelled as orthotropicunidirectional fibrous material. This model would be useful in the analyses such as todetermine strength, fracture toughness and fatigue life that require local stress-straincharacteristic inputs.

Figure 3 Bamboo Strip as Orthotropic Unidirectional Fibrous Composite(Notes * =Amada et al 1996)

2) Laminated CompositesThe bamboo strip could also be modelled as a laminated composite with severalunidirectional continuum layers each with unique mechanical properties.

Figure 4 Bamboo Strip as Multiple Continuum LayersThis model would be appropriate to study the bending behaviour of bamboo strip subjected todifferent loading types and to explain the dissimilarity between the load-displacement curvecharacteristics.

3) 2-Layer CompositeThis is the simplified version of laminated model mentioned above. The bamboo strip is


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composed of two layers of distinctive mechanical properties where the outer layer is muchstronger than the inner layer.

Figure 5 Bamboo Strip as 2-Layer CompositeThis could be the most economical model for future numerical analysis of Laminated BambooStrip Lumber (LBSL)

Numerical WorksThe aim of current numerical analysis is to produce load-displacement curves for bamboostrip subjected to simple bending load. The work started with the 2-layer composite modelbelow.

Figure 6 Load and support arrangement(Dimensions in mm)

Cited Literatures1) Amada, S., Munekata, T., Nagase, Y., Ichikawa, Y., Kirigai, A. and Zhifei, Y. 1996. Themechanical structures of bamboos in viewpoint of functionally gradient and compositematerials. J ournal of Composite Materials, Vol. 30, No. 7. Pp 800-8192) Bai, X., A.W.C. Lee, L. L. Thompson, and D. V. Rosowsky. 1999. Finite element analysis ofMoso bamboo-reinforced southern pine OSB composite beams. Wood and Fiber Science Vol.31 No. 4. Pp 403-415.3) J anssen, J . J . A. 1981. Bamboo in building structures. PhD Thesis. Eindhoven University ofTechnology. 238 pages.4) Lee, A.W.C., X. Bai, and P. N. Peralta. 1996. Physical and mechanical properties ofstrandboard made from Moso bamboo. Forest Products J ournal Vol. 46 No. 11/12. Pp 84-88.5) Lee, A.W.C., X. Bai, and A. P. Bangi. 1997. Flexural properties of bamboo-reinforcedsouthern pine OSB beam. Forest Products J ournal Vol. 47 No. 6. Pp 74-78.


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6) Lee, A.W.C., X. Bai, and A. P. Bangi. 1998. Selected properties of laboratory-madelaminated-bamboo lumber. Holzforschung, Vol. 52, No. 2. Pp 207-210.7) Ganapathy P. M., Zhu H., Zoolagood S. S., Turcke, D. & Espiloy, Z. B. 1999. BambooPanel Boards - a State of the Art Review. Technical Report No. 12. International Network ofBamboo and Rattan (INBAR), Beijing. 115 pages.8) Mansur Ahmad. 2000. Analysis of Calcutta bamboo for structural composite materials. PhDThesis. Virginia Polytechnic Institute and State University. 210 pages.9) Nareswoho Nugroho. 2000. Development of processing methods for bamboo compositematerials and its structural performance. PhD Thesis. The University of Tokyo.

numerical analysis of bamboo

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