https://www.repository.cam.ac.uk/bitstream/1810/247518/1/Sharma%20et%20al%202015%20Elsevier.pdf

Engineered bamboo for structural applications

Novel engineered wood and bamboo composites for structural applications: State-of-art of manufacturing technology and mechanical performance evaluation

Effect of processing methods on the mechanical properties of engineered bamboo

In this work, experimental and numerical study on fracture behaviour of bamboo fiber reinforced epoxy composites is presented. Optimum NaOH concentration for treatment of bamboo fibers was determined through single fiber tensile test and microscopic inspection of fiber surface through SEM (Scanning Electron Microscopy). The results demonstrated that 6% NaOH treated fibers showed maximum ultimate tensile strength of 234 MPa. Single fiber fragmentation test results showed that interfacial adhesion is improved by treating fibers with 6% NaOH. Bamboo fiber reinforced epoxy composite was fabricated using 6% NaOH treated bamboo fibers of length 10 mm, 20 mm and 25 mm with random distribution in epoxy matrix. Mode-I plane strain fracture toughness (K IC ) of bamboo fiber reinforced epoxy composites was investigated based on Linear Elastic Fracture Mechanics (LEFM) approach as per ASTM D5045 . Results showed that composites having 25 mm length of fibers had the largest K IC value of 2.67 MPa.m 1/2 , whereas composites with 10 mm fiber length showed lowest value of fracture toughness K IC of 1.61 MPa.m 1/2 . SEM results revealed that fiber breakage, matrix cracking, fiber matrix debonding and fiber pull out are major causes of failure of composite. Simulation/modelling of crack propagation in CT (Compact Tension) specimen by using FEA software ABAQUS ® showed similar results as experimental values.

Fracture behaviour of bamboo fiber reinforced epoxy composites

Engineered bamboo scrimber: Influence of density on the mechanical and water absorption properties

This study investigated the compressive performance of 24 laminated bamboo specimens made from three different growth portions of the source bamboo. The cross-section of each specimen was 100 mm × 100 mm. The load–strain and load–displacement relationships are obtained from compression tests, and the detailed failure modes, compressive strength and elastic modulus for all specimens are reported. The results show that the mean compressive strength increases with growth portion height, but that the variation in compressive strength also increases with growth portion height. The net result is that the characteristic strength (typically used in the design process) decreases slightly with growth portion height, but not significantly. In contrast, laminated bamboo manufactured from the middle growth portion exhibits the highest elastic modulus, with the variation again increasing with height. Although the source growth portion has a clear effect on the behaviour of laminated bamboo under compression, the paper concludes that the effect is not significant from a design perspective. The results of all the tests are combined to produce a model stress–strain relationship suitable for predicting the performance of laminated bamboo under compression for design purposes. The stress–strain relationship shows that under compression laminated bamboo fails in a ductile manner. Based on the compressive properties obtained in this research, laminated bamboo is a suitable construction material for engineering structures.

Compressive performance of laminated bamboo

This study investigated the mechanical performance of 120 laminated bamboo column specimens under axial compression. Experimental and computational investigations were conducted on axially loaded laminated bamboo columns. The load-deflection and load-strain relationships were obtained from column tests, and the detailed failure modes for all specimens are reported. Squashing or crushing failures were observed for the short columns, and bearing capacity of for the short columns is found to be determined mainly by the compressive strength of the material. However, buckling failures were observed for the longer columns, and the failures involved significant lateral deflection. Deflection caused by initial defects influences the bearing capacity of the specimens more and more obviously as the slenderness ratio increases, and the bigger the slenderness ratio, the bigger the lateral deflection corresponding with the peak load. The variation of ultimate lateral strain and longitudinal strain versus slenderness ratio was also studied. Comparison between the test results, theoretical calculations, and FEM analysis results are reported. An equation for calculating the stability coefficient φ of laminated bamboo columns is proposed. The loading capacities obtained from the equation gives good agreement with the test results.

Mechanical performance of laminated bamboo column under axial compression

Ultimate bending capacity evaluation of laminated bamboo lumber beams

Alpha cellulose was extracted from Bambusa rigida fibers by carrying out Soxhlet extraction and bleaching and alkali treatments with acidified sodium chlorite solution and sodium hydrate solution. Then, cellulose nanofibers were isolated from α-cellulose with the combination of (33 wt%) sulfuric acid and ultrasonic treatment. The nano-sized fibers were successfully isolated, and the average diameters were about 10 to 30 nm. FTIR showed that a majority of the hemicelluloses and lignin were removed from the raw fiber and that the chemical constituents of α-cellulose and cellulose nanofibers were similar. XRD showed that the obtained nano-fibers presented a cellulose I structure, and thus the crystallinity of cellulose nanofibers was significantly increased. TGA showed that the thermal stability of the cellulose nanofibers was significantly improved. The relative crystallinity and thermal degradation temperature of the cellulose nanofibers reached 61.21% and 315.2 °C, respectively.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_08_4_5678_He_Nanofiber_Bambusa/2364

Isolation and Characterization of Cellulose Nanofibers from Bambusa rigida

To evaluate the mechanical performance under two eccentric compression directions, 80 laminated bamboo lumber (LBL) column specimens were tested and analysed. Mechanical properties along two directions were compared. Bamboo nodes and drill hole are two main failure reasons for the specimens under two eccentric directions. More crack layers appeared for radial eccentric direction group specimens due to the layer structure. No matter which eccentric directions they are, the lateral deflection curves are close to the sine line, and the strain across the cross section of the LBL column for each specimen is basically linear throughout the loading process, following standard normal section bending theory. The mechanical properties for two directions are similar with each other and could follow the same design rules. Although the mechanical properties are similar for both LBL columns and parallel bamboo strand lumber (PBSL) columns as a whole, there are still some clear performance differences between the two kinds of materials. Combined all the test data under two eccentric directions, an equation for calculating the radial eccentricity influencing coefficient $$ \varphi_{\text{e}} $$
 of LBL columns is proposed. The calculation results obtained from the equations give a good agreement with the test results.

/pdf/mechanical-evaluation-for-laminated-bamboo-lumber-along-two-49c1b0zf4o.pdf

Qi-sheng Zhang

Papers

Compressive performance of laminated bamboo

Mechanical performance of laminated bamboo column under axial compression

Ultimate bending capacity evaluation of laminated bamboo lumber beams

Isolation and Characterization of Cellulose Nanofibers from Bambusa rigida

Mechanical evaluation for laminated bamboo lumber along two eccentric compression directions