Variations In Tensile Properties Research Articles

Effects of gamma radiation on cyclic olefin copolymers with varied norbornene content: Impacts on structure and properties at sterilization doses

Cyclic olefin copolymer (COC) is a transparent amorphous plastic known for its chemically inertness, biocompatibility, low density, and easy processability. These qualities have led to its widespread adoption in various cutting-edge applications, including the medical, packaging, optical and microelectronics. Radiation sterilization, utilizing high-energy irradiation, is a method for achieving highly effective sterilization of medical products. However, this process can induce changes in the color and properties of the COC materials. In order to comprehend the effects of ionizing radiation on COC, it is crucial to investigate the underlying reaction mechanisms. In this work, the effects of γ-ray irradiation on COC with different norbornene contents were examined. The finding revealed that tertiary alkyl radical content and the degree of oxidative degradation increased with an increase in norbornene content. Furthermore, the macroscopic properties experienced notable shifts, including decreased thermal stability, lower glass transition temperature and the change in color from colorless and transparent to yellow-green. Analysis of the melt index indicated a dominance of cross-linking phenomena with increased absorbed dose for COC with a norbornene content of 35%, while the melt flow rate steadily accelerated with the increase of absorbed dose for COC with norbornene content of 46%, 52% and 57%, leading to a predominant cracking behavior. The variation in tensile properties of the four COCs before and after irradiation were minimal, not exceeding 3%. Overall, this investigation sheds light on the intricate effects of ionizing radiation on COC and highlights the importance of understanding these mechanisms for practical applications.

The Effects of Layer Thickness on the Mechanical Properties of Additive Friction Stir Deposition-Fabricated Aluminum Alloy 6061 Parts

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part’s cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part’s width.

Mechanical Characterization of the Human Abdominal Wall Using Uniaxial Tensile Testing.

It is generally accepted that the human abdominal wall comprises skin, subcutaneous tissues, muscles and their aponeuroses, and the parietal peritoneum. Understanding these layers and their mechanical properties provides valuable information to those designing procedural skills trainers, supporting surgical procedures (hernia repair), and engineering-based work (in silico simulation). However, there is little literature available on the mechanical properties of the abdominal wall in layers or as a composite in the context of designing a procedural skills trainer. This work characterizes the tensile properties of the human abdominal wall by layer and as a partial composite. Tissues were collected from fresh-never-frozen and fresh-frozen cadavers and tested in uniaxial tension at a rate of 5 mm/min until failure. Stress-strain curves were created for each sample, and the values for elastic moduli, ultimate tensile strength, and strain at failure were obtained. The experimental outcomes from this study demonstrated variations in tensile properties within and between tissues. The data also suggest that the tensile properties of composite abdominal walls are not additive. Ultimately, this body of work contributes to a deeper comprehension of these mechanical properties and will serve to enhance patient care, refine surgical interventions, and assist with more sophisticated engineering solutions.

Effect of Rice Husk and Wood Flour on the Structural, Mechanical, and Fire-Retardant Characteristics of Recycled High-Density Polyethylene.

Given the rising consumption of plastic products, it is becoming imperative to prioritize the recycling of plastic items as a solution to reducing plastic waste and environmental pollution. In this context, this research focuses on assessing the impact of incorporating rice husk and wood flour into recycled high-density polyethylene (rec-HDPE) to analyze its mechanical properties, flammability, and thermal stability. The combined rec-HDPE content of wood flour and rice husk varied between 0% and 20%. The rec-HDPE content of maleic anhydride grafted polyethylene (MAPE) was fixed at 3%. Mechanical characteristics such as flexural, tensile, and impact strengths were assessed. Cone calorimetry (CC) tests, limited oxygen index (LOI) tests, and horizontal and vertical burning tests were performed to determine the flammability or fire retardancy of these composites. On the other hand, to characterize the thermal characteristics of these composites, thermogravimetric analysis (TGA) was used. To further characterize the fluctuation in these characteristics, scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) studies were carried out. The mechanical characteristics were found to be increased in response to adding rice husk or wood flour. An 8% increase in tensile strength and a 20% increase in elastic modulus enhancement were recorded for a 20% rice husk-added composite. SEM revealed the reason for the variation in tensile properties, based on the extent of agglomeration and the extent of uniform distribution of fillers in rec-HDPE. Following these lines, the 20% rice husk-added composite also showed a maximum increase of around 6% in its flexural strength and a maximum increase of 50% in its flexural modulus. A decrease in impact strength was recorded for rice husk and wood flour-reinforced composites, compared with unreinforced rec-HDPE. Hybrid composites displayed a lack of mechanical strength due to changes in their nature. FTIR tests were performed for a much more elaborate analysis to confirm these results. Twenty percent of rice husk-added rec-HDPE displayed the best thermal properties that were tested, based on TGA and derivative thermogravimetric (DTG) analysis. This 20% composite also displayed the best fire-retardancy characteristics according to UL 94 tests, cone calorimetry tests, and limited oxygen index tests, due to the barrier created by the silica protective layer. These tests demonstrated that the incorporation of both fillers-rice husk and wood flour-effectively enhanced the thermal, mechanical, and fire-retardant attributes of recycled HDPE.

Effects of infill temperature on the tensile properties and warping of 3D-printed polylactic acid

Although extensive research has been carried out on the effects of temperature on the properties of parts by fused filament fabrication, no study considered the opportunity to use different temperatures and cooling strategies for the contour and the infill region. The purpose of this investigation is to explore such an opportunity through an experimental campaign on polylactic acid. Specifically, the variations in tensile properties and warping occurring with different infill temperatures and cooling methods are documented. The results demonstrate that diversifying process parameters used for the contour and infill of the part allow for significant improvements in mechanical properties without affecting the distortion of the manufactured samples. This result can be achieved by either increasing the nozzle temperature or switching off the cooling fan during infilling.

Assessment of tensile properties across pressure vessel nozzle to primary piping safe-end employing instrumented indentation testing

This study deals with the assessment of tensile properties across the nozzle to primary piping safe-end employing the instrumented indentation testing (IIT). Standard tensile tests were performed in order to validate the results of IIT. Tensile properties were also estimated from conventional hardness test. Both the yield strength and tensile strength measured by IIT were in satisfactory agreement with the results of standard tensile tests and were found superior compared to the values estimated from the conventional hardness measurement. Highest deviation between the results of IIT and tensile tests was found in the regions of weldments. IIT showed as capable of measuring the variation of tensile properties across the pressure vessel nozzle to primary piping safe-end. Moreover, IIT has the advantage over the tensile testing that specimens do not need to be extracted from the studied piece and more detailed distribution of mechanical properties can be acquired.

Precipitates evolution during isothermal aging and its effect on tensile properties for an AFA alloy containing W and B elements

A 20Cr-25Ni-2.5Al alumina-forming austenitic alloy containing W and B elements was aged at 923 K for 5000 h, and the microstructure and tensile properties with different aging time were investigated. NiAl, σ and Laves were observed at grain boundaries (GBs) successively. The matrix was covered by NiAl and Laves with the extension of aging. The evolution of precipitates during aging contributed to the variation of tensile properties. Precipitation of nanosized NbC carbides within grains and σ phase at GBs led to a rapid increase in strength and a decrease in elongation for 500 h aging sample. In the later stage of aging, the coarsening of NiAl and Laves phases, as well as the reduction in dislocation density caused a decline in strength. The coarsening of precipitates upon aging time follows the Ostwald ripening theory. Due to its lower diffusion rate in austenite compared to Mo, W may accelerate the growth of Laves at GBs. Boron was mainly enriched in Laves instead of NiAl, NbC and σ phases after high temperature aging. The addition of W and B improved the precipitation strengthening of Laves, increasing the high temperature tensile strength after long term thermal aging. The difference in tensile properties between room temperature and 923 K is due to the ductile–brittle transition of NiAl. No σ phase was observed within grains even after 5000 h aging and elemental chromium particles occurred around Laves due to boron hindering the growth of σ.

Durability of High-Density Polyethylene (HDPE)- and Polypropylene (PP)-Based Wood-Plastic Composites—Part 1: Mechanical Properties of the Composite Materials

Wood-plastic composites (WPCs) have shown exceptional promise as a building material, especially for outdoor uses. Using renewable wood fiber as the reinforcing filler in WPCs increases the material’s environmental sustainability. While virgin commodity thermoplastics are primarily used in these composites, using post-consumer plastic further contributes to their sustainability. While they are beginning to be used in the Gulf countries, information on their performance, especially durability under harsh desert climates, is sparse. The present investigation on WPCs is based on the two most popularly used thermoplastics in WPCs, virgin high-density polyethylene (HDPE) and polypropylene (PP), with the wood content varying between 0 and 36 wt. %. These were prepared with melt processing from a masterbatch and characterized primarily using thermal methods and tensile properties of their injection molded test pieces. Variations in tensile properties, especially the tensile modulus (MPa), the tensile strength (MPa), and the ultimate extensibility (%) of the composite samples were investigated to determine an optimal wood-fiber loading. For either polymer type, exceeding 27 weight percent of wood fiber resulted in unacceptably low ultimate extensibility of the material.

Examination of steel compatibility with additive manufacturing and repair via laser directed energy deposition

High strength steels are a vital material for aerospace applications but are also prone to damage from fatigue, corrosion, and wear. Additive manufacturing (AM) processes such as laser directed energy deposition (L-DED) offer a means for repairing both the geometry and structure of damaged steels; however, significant variation in tensile properties have been reported following repair. While previous studies have tried to improve performance through postdeposition heat treatment, such practices may not be possible for commercial parts due to risks of distortion and thermal damage to the substrate. Instead, this investigation analyses the role of the intrinsic heat treatment effect on as-deposited tensile properties through a detailed review of both AM and AM repair literature. By assessing a wide variety of high strength steels, the links between conventional heat treatment parameters and steel performance in AM are established, and the role of steel composition understood. This review is supported by additional AM and L-DED repaired samples, with consistent parameters used between steels to ensure similar thermal histories, and eliminate potential discrepancies seen between AM machines. The results demonstrate the effect of intrinsic heat treatment on martensitic and precipitation hardening steels, the role of residual heat and heat extraction through the substrate, and flag potential issues faced by steels at risk of temper embrittlement. Taken together, these findings provide a clear vision for the advancement of AM repair and the optimization of mechanical performance.

Effects of work-hardening and post thermal-treatment on tensile behaviour of solder-affected copper

In order to explore the reuse potential of waste/scraped copper, an effective characterization of its functional properties under various operating conditions is of great practical importance. The present paper is an attempt to reconnoiter the solder-affected waste copper for high-value engineering applications through the characterization of major mechanical properties. More specifically, the tensile properties of traditional lead-solder-affected copper are investigated and analyzed under the influence of work-hardening and post-thermal treatments. The influential effects of individual elements of the solder on the tensile properties of copper are discussed in a comparative fashion, in which two additional alloy samples, namely, high-copper/tin alloy and high-copper/lead alloy are taken into consideration together with those of copper–tin–lead–alloy as well as pure copper samples. The results of the investigation show that the inclusion of trace-amount of tin and lead in copper affects the corresponding tensile behaviour quite significantly. The strength rising trends due to cold working are observed to be more prominent for the inclusion of lead compared to that of tin. The post-thermal treatments of the work-hardened alloy samples have lowered ultimate strength, yield strength and elastic modulus, but increased the fracture elongation at elevated temperatures. Strain rate variations are also found to be highly influential on all the tensile properties of the solder-affected alloys. Micrographs of the alloy samples have verified the changes in grain shape and grain size responsible for the variation of tensile properties.

Microstructure and enhanced tensile properties of AlCo CrFeNi high entropy alloys with high Co content fabricated by laser melting deposition

AlCoxCrFeNi (x = 2.2, 2.8) high entropy alloys (HEAs) were successfully prepared by multi-layer and multi-channel laser melting deposition (LMD). The tensile properties of the LMD-fabricated AlCoxCrFeNi HEAs were investigated. The phase evolution of these alloys was examined by X-ray diffraction and compared with existing models. The microstructure of the alloys was characterized using scanning electron microscopy and electron backscatter diffraction. It is found that Co element can promote the phase transformation from BCC phase to FCC phase in the as-deposited AlCoxCrFeNi HEAs, and the volume fraction of FCC phase increases from 51.4% to 74.6% as the Co content increases from 36.2 at% to 40.8 at%. With the increase of Co content, the grain size of BCC phase in the alloys decreases and a larger amount of fine needle-like BCC phase appears in the FCC matrix. Tensile testing shows that higher Co content in the deposited AlCoxCrFeNi alloy can enhance its plasticity without significantly compromising its ultimate strength. As the Co content increases, the fracture strain increases from 5.9% to 15.4%, while the yield strength reduces from 450 MPa to 360 MPa and the ultimate tensile strength increases from 734 MPa to 739 MPa. The variations in tensile properties of the AlCoxCrFeNi alloy result from phase structure changes and microstructure evolution. Through this research, it is demonstrated that enhancement of the tensile properties of the LMD-fabricated AlCoCrFeNi HEAs can be realized by increasing the content of Co element.

Influence of ageing on high temperature tensile deformation of a Ni-based superalloy, HAYNES 282

The effect of ageing time and temperature on the deformation mechanism and corresponding tensile properties are investigated in a γ/γ′ Ni-based superalloy, HAYNES 282. Through a systematic variation in duration (24 h and 216 h) and temperature of ageing (650 °C and 760 °C), a significant variation in strengthening microstructural features was achieved in the resulting microstructures. While in one case (650 °C, 24 h ageing condition), a microstructure with no γ′ was observed, for the rest of the cases, γ′ precipitates of varied sizes were observed. In one specific case (760 °C, 216 h ageing condition), very fine (4–6 nm) MC carbides were observed along with γ′ precipitates; in which these tiny MC carbides became the deciding factor for strength over γ′ precipitates. While common knowledge of smaller γ′ precipitates giving higher strength could explain the higher strength at 760 °C, 24 h ageing condition as compared to 650 °C, 216 h ageing condition, the further increase in strength in case of 760 °C, 216 h ageing condition, even with much larger γ′ precipitates was something quite interesting and counterintuitive. This paper elucidates this puzzling observation. The variation of tensile properties of these wide varieties of microstructures will be described in this paper in light of the underlying deformation mechanisms. A change in deformation mechanism from planar slip (microstructure with no γ′) to twinning (microstructure with γ′) and Orowan-looping (microstructure with γ′ along with fine nano carbides) as a function of microstructure explains the difference in strength, ductility, and strain hardening phenomena among the varied ageing conditions.

Relationship between microstructure and strain-hardening behaviour of 3D printed engineered cementitious composites

The tensile behaviour of engineered cementitious composites (ECC) is highly dependent on their microstructure characteristics. To date, the strain-hardening behaviour of printed ECC in relation to its microstructure is not yet fully understood. This study presents a systematic investigation on the macroscopic mechanical properties of normal and printed ECC with various polyethylene (PE) fibre lengths (6 and 12 mm) in relation to their microstructural features in terms of pore structure characteristics, fibre orientation and fibre dispersion through a series of mechanical tests and X-ray computed tomography (CT) and backscattered electron (BSE) image acquisition, processing and analysis. Results indicate that it is desirable to use block specimens for mould-casting fabrication as contrast to printed ECC samples. The printed ECC containing 1.5 vol% 6 mm and 0.5 vol% 12 mm PE fibres by extrusion-based 3D printing exhibits unique tensile ductility of over 5% and average crack width of less than 100 μm. Regarding pore structure, normal ECC has a higher probability of large pores (over 1 mm3) than printed ECC, which would increase the risk of damage localization and lead to a significant variation in tensile properties. Besides, normal ECC with thickness of 30 mm and printed ECC possess a similar fist cracking strength as indicated by similar pore size and fracture toughness. Compared to normal ECC, printed ECC has a more uniform dispersion of PE fibres, the orientation of which is more perpendicular to the loading direction, resulting in a higher average tensile strength and strain capacity than normal ECC.

Precipitate coarsening and mechanical properties in 6082 aluminium alloy during long-term thermal exposure

Long-term thermal stability is essential for the use of 6082 aluminium alloy in battery packaging. Precipitate coarsening and property changes in the alloy during 1000 h of thermal exposure at 100, 125, 150, and 175 °C were studied experimentally and theoretically. Variations of tensile properties were exhibited. The microstructural and nanoscale precipitates were characterized by microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Alloys exposed at 100 °C and 125 °C were thermally stable, retaining the strength above 340 MPa after a thermal exposure of 1000 h. Alloys exposed at 150 and 175 °C lost 25% and 48% of their respective strengths after 1000 h of exposure, reaching 253 and 178 MPa. Precipitates gradually increase in size with increasing thermal exposure time or temperature, while their number density decreases. After thermal exposure at 175 °C for 1000 h, the length of precipitates increased from 31 nm to 328 nm, and the coarsening rate of precipitates was 2.22 × 10−30 m3s−1. Comparing the experimental and theoretical coarsening rates showed that the Kuehmann–Voorhees (KV) model is suitable for calculating the precipitate coarsening rate of 6082 aluminium alloy. This study proposes a new method to predict the strength of aluminium alloy after thermal exposure; the effect of precipitate coarsening on alloy properties is also discussed quantitatively.

Assessment of intra-build variations in tensile strength in electron beam powder-bed fusion Ti–6AL–4V part 1: Effects of build height

In this work, rectangular blocks of electron beam powder-bed fusion (PBF-EB) additively manufactured (AM) Ti–6Al–4V were built, such that a total of 68 mini-tensile test coupons could be extracted for mechanical testing over a range of build height and build plate locations. These as-built tensile test coupons were uniaxially tested to fracture and subsequently studied via scanning electron microscopy, micro X-ray computed tomography, and inert gas fusion chemical analysis to systematically study the intra-build variations in tensile properties, microstructure, porosity, and chemistry. A strong correlation was observed between YS and build height, where YS was observed to decrease with increasing build height, up to 35 mm. There were no significant contributions to this variation in yield strength (YS) from build location, porosity, grain size, or crystallographic texture. Inert gas fusion oxygen measurements reveal the same trend, suggesting that oxygen content variation as a function of build height is contributing to the observed YS variation. The source of the oxygen content variation is thought to be a transient source of oxygen, such as moisture in the powder and build chamber. The establishment of this oxygen variation and its correlation to tensile properties motivates and facilitates improvements to PBF-EB Ti–6Al–4V processing, including powder mixing and handling.

Assessment of intra-build variations in tensile strength in electron beam powder-bed fusion Ti–6Al–4V part 2: Effects of powder mixing

In Part 2 of this paper series, high-throughput tensile testing and characterization of porosity, microstructure, and oxygen content was carried out on Ti–6Al–4V samples that were fabricated via electron beam powder-bed fusion (PBF-EB) to test our hypothesis that current industrial powder mixing strategies lead to stochastic chemistry content and tensile property variation throughout a given build. Fifteen rectangular blocks were built at locations across the entire build plate and machined into high-throughput tensile racks that contained 25 mini tensile coupons each (375 total specimens). There was a spread of 138.9 MPa in yield strength (YS) across all specimens. Considering the YS spread was only 74.2 MPa for a virgin build with no mixing, as detailed in Part 1, the difference between these two YS ranges is expected to be attributed to mixing. To determine the cause for this observed spread in YS, systematic investigation of porosity, microstructure, and oxygen content was performed via scanning electron microscopy (SEM), micro X-ray computed tomography (μXCT), inert gas fusion, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The large variation in YS for these specimens could not be attributed to internal porosity, fracture surface porosity, α-lath thickness, or crystallographic texture. Inert gas fusion measurements indicated large, stochastic variation in oxygen content, and measurements via ToF-SIMS near the fracture surfaces indicate localized chemistry variations that could be responsible for the large variations in tensile properties, specifically the yield strength. Specific alternative powder mixing and reuse methodologies are proposed to mitigate undesirable chemistry and tensile property variation within PBF-EB Ti–6Al–4V.

Microstructure and mechanical behaviors of Al/Cu laminated composites fabricated by accumulative roll bonding and intermediate annealing

Strength and toughness of laminated composites with alternatively stacked “brick-and-mortar” structure can be synchronously improved along the direction parallel to the layer interface. However, it is still a challenge to prepare high-performance laminated composites in large quantities to meet industrial needs. In this work, we employ accumulative roll bonding (ARB) and/or intermediate annealing to prepare Al/Cu laminated composites as cheaper substitutes for Cu alloys due to lightweight and considered electrical conductivity. Our results show that the ARB process decreases the layer thicknesses and grain sizes, and improves the Vickers micro-hardness of Al/Cu laminated composites. As the ARB cycle increases from 1 to 8, the tensile strength firstly increases from 279.20 MPa to 358.71 MPa, and then decreases to 317.88 MPa. Meanwhile, the uniform elongation firstly increases from 1.25% to 1.71%, and then decreases to 0.58%. These variations of tensile properties are tightly linked to the layer-integrity and microstructures of Al and Cu layers. Moreover, the intermediate annealing (350 °C for 30 min) applied after every 2 ARB cycles can significantly increase the tensile strength, uniform elongation and elongation to failure, especially for Al/Cu laminated composites with high ARB cycles, because intermediate annealing remarkably improves the interfacial metallurgical bonding and continuity/integrity of Al and Cu layers. However, the final annealing for long time would introduce brittle intermetallics (like AlCu and Al2Cu), and therefore deteriorate the tensile ductility. This work provides a new treatment process for fabricating Al/Cu laminated composites with synchronously increasing strength and ductility.

Interfacial microstructure and property of 6061 aluminium alloy/stainless steel hybrid inertia friction welded joint with different steel surface roughness

Considering that the friction welded aluminium (Al) alloy to stainless steel (designated as steel) hybrid structures are of great potential to be served as high-performance light-weight pipelines, spindle, etc., this paper highlights the importance of steel surface roughness ( S a ) by characterising its effect on the interfacial microstructure and mechanical properties of the resultant 6061 Al alloy/304 stainless steel inertia friction welded joint. The insufficient frictional heat and material flow could easily cause the appearance of un-bonded area in the central region of the interface when the steel surface roughness was higher than 0.68 μm (subjected to grinding), whereas, in the joint produced by Al alloy and polished steel ( S a = 0.02 μm), an amorphous Fe-Al layer was observed in the central region indicating an metallurgical reaction was achieved. In the outer region of the interface, a reaction layer was observed in all the joints consisting of steel with varying degrees of surface roughness. Further inspection of such region revealed a partially crystallised Fe 2 Al 5 layer and an amorphous layer were formed. The energy calculation indicated that the amorphous phase might form when the composition deviated from that of Fe 2 Al 5 owing to a negative formation enthalpy and Gibbs free energy. Upon decreasing steel surface roughness, the joint strength showed a noticeable increasing trend. The variation of tensile properties was then clarified by studying the correlation between the interfacial microstructure and fractography. Therefore the steel surface condition is never too over-emphasised when joining with other metal with lower stiffness by inertia friction welded. • The effect of surface roughness on the property of inertia friction welded Al alloy/steel joint was highlighted. • The formation of amorphous layer and partially crystallised layer at weld interface were analysed. • The effect of steel surface roughness on the interfacial microstructure and fracture behaviour of Al alloy/steel joint was analysed.

Tensile Behavior of Geometrically Irregular Bagasse Fiber

In the present work, an investigation on the surface topography and geometry variation of bagasse fibers was correlated with their mechanical properties via image analysis. The fibers were tested under a universal tensile testing machine and the diameter of the fibers was calculated using images obtained in a digital microscope. Furthermore, surface characterization and quantification were also performed using images obtained via SEM. The results showed that the surface roughness of alkali-treated bagasse fiber increased compared to that of the untreated one. Moreover, it was observed that the diameter variation of bagasse fiber along its length and among different fibers is not only variable but also unpredictable. The tensile test results revealed that bagasse fibers showed lower stress at a rupture with considerable scatter. It can be inferred that the synergistic effect of thick bagasse fiber, bagasse fiber diameter variations along its length and among fibers, and the fiber fracture mechanism establishes a local condition for fracture and resulted in such variations in tensile properties. Finally, the results clearly showed that the two-parameter Weibull fit the experimental data fairly well (R2=0.97). The Weibull modulus (m) was found to be 1.7, indicating that the strength distribution is high.

Variation in Tensile Properties of Single Vascular Bundles in Moso Bamboo

Abstract Moso bamboo (Phyllostachys edulis), an apt example of an anisotropic, functionally graded composite material, is the most important commercial bamboo species of China. This species has excellent mechanical properties due to its unique vascular bundle structure. This article examines the variation in mechanical properties of single vascular bundles with respect to their location within a bamboo culm. The mechanical exfoliation method was used to prepare the single vascular bundle. This study found that moso bamboo has superior stiffness and strength. Additionally, the variation in properties was large in the radial direction but minimal in longitudinal direction. The large variation in mechanical properties of vascular bundles can be ascribed to the synergistic effect of the fibrous sheath and parenchyma rather than to changes in fibrous sheath properties. This study provides a basis for the structure application for moso bamboo.