M. Abshirini, M. Altan, Yingtao Liu, M. Saha, L. Cummings, T. Robison
This paper presents the fabrication and characterization of porous polydimethylsiloxane (PDMS) plates. The framework for obtaining porous PDMS is based on the solvent evaporation induced phase separation technique. A mixture of PDMS, water, and tetrahydrofuran (THF) with different concentrations is prepared. The three phases are stirred to reach a highly stable and viscous solution. The THF and water phases are evaporated during a curing cycle by applying a stepping heat treatment. The porous PDMS sheets with a wide range of pore sizes are fabricated by controlling the ratio of water to THF in the mixture. The confocal microscopy images are used to characterize the average pore size and the pore size distribution in the structures. Dogbone samples following the ASTM standard D412 are cut from the porous plates by utilizing a designed cutting die and mechanical press. The specimens are tested under tensile loading to evaluate the effect of the pore size on the mechanical properties of the porous structure. The results demonstrate the ability of the proposed solvent evaporation method to control the stiffness of the porous structure by changing the non-solvent to the solvent ratio in the mixture.
{"title":"Manufacturing of Porous Polydimethylsiloxane (PDMS) Plates Using Solvent Evaporation Induced Phase Separation Technique","authors":"M. Abshirini, M. Altan, Yingtao Liu, M. Saha, L. Cummings, T. Robison","doi":"10.1115/IMECE2020-24062","DOIUrl":"https://doi.org/10.1115/IMECE2020-24062","url":null,"abstract":"\u0000 This paper presents the fabrication and characterization of porous polydimethylsiloxane (PDMS) plates. The framework for obtaining porous PDMS is based on the solvent evaporation induced phase separation technique. A mixture of PDMS, water, and tetrahydrofuran (THF) with different concentrations is prepared. The three phases are stirred to reach a highly stable and viscous solution. The THF and water phases are evaporated during a curing cycle by applying a stepping heat treatment. The porous PDMS sheets with a wide range of pore sizes are fabricated by controlling the ratio of water to THF in the mixture. The confocal microscopy images are used to characterize the average pore size and the pore size distribution in the structures. Dogbone samples following the ASTM standard D412 are cut from the porous plates by utilizing a designed cutting die and mechanical press. The specimens are tested under tensile loading to evaluate the effect of the pore size on the mechanical properties of the porous structure. The results demonstrate the ability of the proposed solvent evaporation method to control the stiffness of the porous structure by changing the non-solvent to the solvent ratio in the mixture.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91220728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The objective of this study is to investigate the effect of film thickness on the bandgap of oxygen (O2)-doped titanium nitride (TiN) thin films. To accomplish this, high-quality two-dimensional O2-doped TiN films have been prepared on single-crystal sapphire substrates using a pulsed laser deposition method. The film thicknesses were varied from 3 to 100 nm by varying the number of laser pulses, while other deposition parameters are kept constant. X-ray diffraction (XRD) patterns have shown that the films grow in (111) orientation on the sapphire substrate. The increase in the intensity of the XRD (111) peak also demonstrates a better orientational alignment of the TiN films with substrate as the film thickness increases. The x-ray rocking curve has been used to measure the full width half maxima (FWHM) for each film. The FWHM values has been found to vary from 0.07 to 0.2° as the film thickness decreases. This is taken to indicate that the grain size decreases with a decrease in film thickness. Ultraviolet visible spectroscopy measurements in the wavelength range (200–800 nm) have been performed as well, which indicates an increase in the bandgap of O2-doped TiN films with a decrease in film thickness. The decrease in the film thickness leads to a blue shift of the peak in the ultraviolet-visible absorption (UV-A) region; this blueshift is accompanied by an increase in the bandgap of O2-doped TiN from 3.2 to 3.8 eV. The change in the bandgap due to a change in film thickness has been explained using the quantum confinement effect.
{"title":"Blue Shift in Ultraviolet Absorption Spectra of Oxygen Doped Titanium Nitride Thin Films","authors":"M. Roy, Dhananjay Kumar","doi":"10.1115/IMECE2020-24113","DOIUrl":"https://doi.org/10.1115/IMECE2020-24113","url":null,"abstract":"\u0000 The objective of this study is to investigate the effect of film thickness on the bandgap of oxygen (O2)-doped titanium nitride (TiN) thin films. To accomplish this, high-quality two-dimensional O2-doped TiN films have been prepared on single-crystal sapphire substrates using a pulsed laser deposition method. The film thicknesses were varied from 3 to 100 nm by varying the number of laser pulses, while other deposition parameters are kept constant. X-ray diffraction (XRD) patterns have shown that the films grow in (111) orientation on the sapphire substrate. The increase in the intensity of the XRD (111) peak also demonstrates a better orientational alignment of the TiN films with substrate as the film thickness increases. The x-ray rocking curve has been used to measure the full width half maxima (FWHM) for each film. The FWHM values has been found to vary from 0.07 to 0.2° as the film thickness decreases. This is taken to indicate that the grain size decreases with a decrease in film thickness. Ultraviolet visible spectroscopy measurements in the wavelength range (200–800 nm) have been performed as well, which indicates an increase in the bandgap of O2-doped TiN films with a decrease in film thickness. The decrease in the film thickness leads to a blue shift of the peak in the ultraviolet-visible absorption (UV-A) region; this blueshift is accompanied by an increase in the bandgap of O2-doped TiN from 3.2 to 3.8 eV. The change in the bandgap due to a change in film thickness has been explained using the quantum confinement effect.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91306670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Results of online acoustic emission (AE) monitoring during fatigue crack growth rate (FCGR) experiments on a stainless steel SS 316 LN are presented in this paper. Two specimen geometries — viz., standard compact tension (C(T)) specimens as well as side-grooved C(T) specimens were considered for experiments at ambient temperature and at 600°C (873K). There is a good correspondence between crack length increment and the increase in AE cumulative count and cumulative energy during the experiments. The side grove introduced on the thickness direction of the test specimen constrains the plastic zone ahead of the crack tip, thereby enforcing plane strain conditions at the crack. Reduced AE activity at initial stages of crack growth was observed for side grooved samples. The transition to Stage-II crack growth was observed using acoustic emission (AE) technique which otherwise was not visible from the fatigue crack growth plot. The work further attempts to correlate the AE parameters obtained during elevated temperature (873K) fatigue crack growth in stainless steel. For the purpose of acquiring AE signals outside the heated zone, a waveguide was used to transmit the acoustic waves from the specimen at high temperature. A correlation between crack advance and AE parameters was obtained from the elevated temperature tests.
{"title":"Evaluation of Fatigue Crack Growth Characteristics on Stainless Steel SS 316 LN Using Acoustic Emission Technique","authors":"R. Prakash, M. Thomas","doi":"10.1115/IMECE2020-23751","DOIUrl":"https://doi.org/10.1115/IMECE2020-23751","url":null,"abstract":"\u0000 Results of online acoustic emission (AE) monitoring during fatigue crack growth rate (FCGR) experiments on a stainless steel SS 316 LN are presented in this paper. Two specimen geometries — viz., standard compact tension (C(T)) specimens as well as side-grooved C(T) specimens were considered for experiments at ambient temperature and at 600°C (873K). There is a good correspondence between crack length increment and the increase in AE cumulative count and cumulative energy during the experiments. The side grove introduced on the thickness direction of the test specimen constrains the plastic zone ahead of the crack tip, thereby enforcing plane strain conditions at the crack. Reduced AE activity at initial stages of crack growth was observed for side grooved samples. The transition to Stage-II crack growth was observed using acoustic emission (AE) technique which otherwise was not visible from the fatigue crack growth plot.\u0000 The work further attempts to correlate the AE parameters obtained during elevated temperature (873K) fatigue crack growth in stainless steel. For the purpose of acquiring AE signals outside the heated zone, a waveguide was used to transmit the acoustic waves from the specimen at high temperature. A correlation between crack advance and AE parameters was obtained from the elevated temperature tests.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90145214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Countless organisms in nature have adapted high-aspect-ratio micro-/nano-fibrillar arrays on their functional surfaces for achieving special and often optimized functionalities using earthly abundant materials. At the core of nanoscience and nanotechnology, rationally mimicking nature offers a promising route to create multifunctional superstructures that capture organisms and biological materials’ intriguing responsive and self-adjusting properties. Prior work has demonstrated that hierarchical vertically aligned multi-walled carbon nanotube (VA-MCNT) arrays can achieve ten folds of adhesive force comparing to the fibrillar structures of the gecko toe pads. However, little is known with regard to their wettability at the ultimate atomistic level, and how this may influence the adhesive performance and/or self-cleaning capabilities, despite water condensation and bridging are common phenomena at this length scale. In present study, molecular dynamics (MD) simulations were performed using Large-Scale Atomic / Molecular Massively Parallel Simulator (LAMMPS). Results indicate that commonly believed hydrophobic defect free CNTs (i.e., carbon sp2 hybridization without any dangling bonds) become super-hydrophilic at this length/temporal scale. The critical factors that influence the number of H-Bonds in water are: i) tube-tube spacing; and ii) shape/size and position of the water nanodroplet; and iii) how many droplets exists and how many nanotubes are bridged by the droplets. Chirality has little effect on the water interfacial behaviors. Future work will focus on the effect of water condensation and bridging on the adhesive and self-cleaning properties of carbon-based bio-inspired fibrillar dry adhesives considering defects and saline water.
{"title":"Nano-Scale Wettability of Free-Standing Capped Carbon Nanotube Arrays","authors":"Miray Ouzounian, Travis Shihao Hu","doi":"10.1115/IMECE2020-23695","DOIUrl":"https://doi.org/10.1115/IMECE2020-23695","url":null,"abstract":"\u0000 Countless organisms in nature have adapted high-aspect-ratio micro-/nano-fibrillar arrays on their functional surfaces for achieving special and often optimized functionalities using earthly abundant materials. At the core of nanoscience and nanotechnology, rationally mimicking nature offers a promising route to create multifunctional superstructures that capture organisms and biological materials’ intriguing responsive and self-adjusting properties. Prior work has demonstrated that hierarchical vertically aligned multi-walled carbon nanotube (VA-MCNT) arrays can achieve ten folds of adhesive force comparing to the fibrillar structures of the gecko toe pads. However, little is known with regard to their wettability at the ultimate atomistic level, and how this may influence the adhesive performance and/or self-cleaning capabilities, despite water condensation and bridging are common phenomena at this length scale. In present study, molecular dynamics (MD) simulations were performed using Large-Scale Atomic / Molecular Massively Parallel Simulator (LAMMPS). Results indicate that commonly believed hydrophobic defect free CNTs (i.e., carbon sp2 hybridization without any dangling bonds) become super-hydrophilic at this length/temporal scale. The critical factors that influence the number of H-Bonds in water are: i) tube-tube spacing; and ii) shape/size and position of the water nanodroplet; and iii) how many droplets exists and how many nanotubes are bridged by the droplets. Chirality has little effect on the water interfacial behaviors. Future work will focus on the effect of water condensation and bridging on the adhesive and self-cleaning properties of carbon-based bio-inspired fibrillar dry adhesives considering defects and saline water.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83950664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Residual Stress distribution and parametric influence of friction are studied for the split sleeve cold expanded holes in Al 2024 T351 alloy, by developing a three-dimensional finite element model of the process. Fastener holes in the alloy are necessary for the manufacturing process, but they create a potential area for stress concentration, which eventually leads to fatigue under cyclic loading. Beneficial compressive residual stress distribution as a result of the split sleeve cold expansion process provides retardation against crack initiation and propagation at the critical zones near hole edges. In this parametric study, the influence of friction between contact surfaces of the split sleeve and mandrel is numerically investigated. Hole reaming process after split sleeve cold expansion is often not discussed. Without this post-processing procedure, split sleeve cold expansion is incomplete in practice, and its purpose of providing better fatigue performance is invalidated. This study presents results and an overview of the significance of friction with the consideration of the postprocessing of split sleeve cold expansion. The numerical results show that with increasing friction coefficient, compressive residual stress reduces significantly at the mandrel entry side, which makes the hole edge more vulnerable to fatigue. The different aspects of finite element modeling approaches are also discussed to present the accuracy of the prediction. Experimental residual stress observation or visual validation is expensive and time-consuming. So better numerical prediction with the transparency of the analysis design can provide critical information on the process.
{"title":"Effect of Friction on Residual Stress Distribution Induced by Split Sleeve Cold Expansion Process","authors":"Mithu Dey, Dave Kim, H. Tan","doi":"10.1115/IMECE2020-24240","DOIUrl":"https://doi.org/10.1115/IMECE2020-24240","url":null,"abstract":"\u0000 Residual Stress distribution and parametric influence of friction are studied for the split sleeve cold expanded holes in Al 2024 T351 alloy, by developing a three-dimensional finite element model of the process. Fastener holes in the alloy are necessary for the manufacturing process, but they create a potential area for stress concentration, which eventually leads to fatigue under cyclic loading. Beneficial compressive residual stress distribution as a result of the split sleeve cold expansion process provides retardation against crack initiation and propagation at the critical zones near hole edges. In this parametric study, the influence of friction between contact surfaces of the split sleeve and mandrel is numerically investigated. Hole reaming process after split sleeve cold expansion is often not discussed. Without this post-processing procedure, split sleeve cold expansion is incomplete in practice, and its purpose of providing better fatigue performance is invalidated. This study presents results and an overview of the significance of friction with the consideration of the postprocessing of split sleeve cold expansion. The numerical results show that with increasing friction coefficient, compressive residual stress reduces significantly at the mandrel entry side, which makes the hole edge more vulnerable to fatigue. The different aspects of finite element modeling approaches are also discussed to present the accuracy of the prediction. Experimental residual stress observation or visual validation is expensive and time-consuming. So better numerical prediction with the transparency of the analysis design can provide critical information on the process.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90414571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Small-size wearable multi-gas sensor with high selectivity and sensitivity is demanded for detecting various harmful gases with high sensitivity in chemical plants, various mines, volcanos, oil and gas fields. Graphene is considered to be the most promising gas-sensitive material due to its large specific surface area and high electron mobility. Many studies have shown that it has a high sensitivity to many gases such as NH3, CO, NO2, H2O, and so on. However, the lack of gas selectivity limits the further application of graphene to gas sensing field. In this study, a first-principle calculation was used to investigate the effect of strain on the gas adsorption behavior of graphene. As a result, it was found that the adsorption behavior of H2O and CO molecules was changed by strain. The adsorption energy of both gases increased monotonically with strain. For carbon monoxide molecules, desorption occurred when the applied tensile strain reached about 5%. These analytical results clearly indicated that there is a possibility of the high selectivity of plural gases by applying appropriate critical strain at which its adsorption changes to desorption. To verify this result, the strain-controlled sensor using graphene was developed. The sensor is composed of graphene and electrodes mounted on a deformable substrate. The high-quality graphene is synthesized on copper by LPCVD (low pressure chemical vapor deposition), and then transferred to the PDMS (Polydimethylsiloxane) substrate using PMMA (Poly methyl methacrylate) as a support layer. It was found that the graphene was monolayer and successfully transferred to the target substrate. The effect of strain on the adsorption of some gases was validated by measuring the change of the resistivity of graphene under the application of uniaxial strain.
{"title":"Development of a Strain-Controlled Graphene-Based Highly Sensitive Gas Sensor","authors":"Xiangyu Qiao, Qinqiang Zhang, Ken Suzuki","doi":"10.1115/IMECE2020-23581","DOIUrl":"https://doi.org/10.1115/IMECE2020-23581","url":null,"abstract":"\u0000 Small-size wearable multi-gas sensor with high selectivity and sensitivity is demanded for detecting various harmful gases with high sensitivity in chemical plants, various mines, volcanos, oil and gas fields. Graphene is considered to be the most promising gas-sensitive material due to its large specific surface area and high electron mobility. Many studies have shown that it has a high sensitivity to many gases such as NH3, CO, NO2, H2O, and so on. However, the lack of gas selectivity limits the further application of graphene to gas sensing field. In this study, a first-principle calculation was used to investigate the effect of strain on the gas adsorption behavior of graphene. As a result, it was found that the adsorption behavior of H2O and CO molecules was changed by strain. The adsorption energy of both gases increased monotonically with strain. For carbon monoxide molecules, desorption occurred when the applied tensile strain reached about 5%. These analytical results clearly indicated that there is a possibility of the high selectivity of plural gases by applying appropriate critical strain at which its adsorption changes to desorption. To verify this result, the strain-controlled sensor using graphene was developed. The sensor is composed of graphene and electrodes mounted on a deformable substrate. The high-quality graphene is synthesized on copper by LPCVD (low pressure chemical vapor deposition), and then transferred to the PDMS (Polydimethylsiloxane) substrate using PMMA (Poly methyl methacrylate) as a support layer. It was found that the graphene was monolayer and successfully transferred to the target substrate. The effect of strain on the adsorption of some gases was validated by measuring the change of the resistivity of graphene under the application of uniaxial strain.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75394628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanoporous 2D materials such as grapheme and MoS2 promises better filtrations in water channels. However certain parameters that affects these materials for effective deployment need to be studied. In this paper, molecular dynamics (MD) simulation was performed to study the effects of defects that could increase the prospect of tuning the efficiency of the materials in the transportation, catalysis and mechanical reaction efficiency. Consideration of the interfaces between them could lead to improved functionalities of the materials. This paper systematically compares MoS2 and graphene membranes to highlight specific features and benefits. the Young’s modulus of the pristine monolayer MoS2 was calculated to be 447GPa while that of the defective MoS2 was found to be in the range of (314–374) GPa. The Young’s Modulus for Graphene was 783.2 GPa. The relative variation of the Young’s modulus on MoS2 is in the range (13–35) % while that of graphene is (13–21) %. From the results obtained, the maximum pressure that the MoS2 can withstand depends not just on the spacing and size of the nanopores, but also on the area of the defects in the membrane. These findings could help build and proliferate tunable filtration nanodevices and other applications.
{"title":"Effects of Defects on Nanoporous Graphene and MoS2","authors":"P. Oviroh, Lesego Mohlala, T. Jen","doi":"10.1115/IMECE2020-23442","DOIUrl":"https://doi.org/10.1115/IMECE2020-23442","url":null,"abstract":"\u0000 Nanoporous 2D materials such as grapheme and MoS2 promises better filtrations in water channels. However certain parameters that affects these materials for effective deployment need to be studied. In this paper, molecular dynamics (MD) simulation was performed to study the effects of defects that could increase the prospect of tuning the efficiency of the materials in the transportation, catalysis and mechanical reaction efficiency. Consideration of the interfaces between them could lead to improved functionalities of the materials. This paper systematically compares MoS2 and graphene membranes to highlight specific features and benefits. the Young’s modulus of the pristine monolayer MoS2 was calculated to be 447GPa while that of the defective MoS2 was found to be in the range of (314–374) GPa. The Young’s Modulus for Graphene was 783.2 GPa. The relative variation of the Young’s modulus on MoS2 is in the range (13–35) % while that of graphene is (13–21) %. From the results obtained, the maximum pressure that the MoS2 can withstand depends not just on the spacing and size of the nanopores, but also on the area of the defects in the membrane. These findings could help build and proliferate tunable filtration nanodevices and other applications.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74270256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, AS4/914 grade carbon fibre reinforced plastic (CFRP) laminates with two different quasi-isotropic (QI) layup sequences are compared for their performance under four point bend flexure fatigue loads. The QI laminates were designated and fabricated as Laminate-1 (L1) [0/45/-45/90]2S and Laminate-2 (L2) [0/90/45/-45]2S, respectively. These laminates were designed, such that the 0° layers are placed at a similar position in both the laminate systems by changing the other layers. During the test, load and displacement data was monitored online along with instantaneous number of constant load amplitude (CLA) fatigue cycles to calculate the stiffness degradation. Three load levels of 90%, 80%, and 70% of the ultimate flexure strength (UFS) were chosen for assessing the flexure fatigue behavior of the laminates. A few tests were also attempted under variable amplitude loads: (i) high amplitude cycles followed by low amplitude and (ii) low amplitude cycles followed by high amplitude to examine load sequence effect on fatigue life, if any, as compared to the fatigue life under CLA. It has been observed that the laminate L1 performs better under higher amplitudes, while the laminate L2 shows increased life under lower load and variable amplitudes. The results obtained in the form of data plots and failure modes, supported by microscopic images, are discussed in the paper.
{"title":"An Investigation on Flexural Fatigue Behavior of CFRP Quasi-Isotropic Laminates","authors":"K. Panbarasu, V. Ranganath, R. Prakash","doi":"10.1115/IMECE2020-23685","DOIUrl":"https://doi.org/10.1115/IMECE2020-23685","url":null,"abstract":"\u0000 In this study, AS4/914 grade carbon fibre reinforced plastic (CFRP) laminates with two different quasi-isotropic (QI) layup sequences are compared for their performance under four point bend flexure fatigue loads. The QI laminates were designated and fabricated as Laminate-1 (L1) [0/45/-45/90]2S and Laminate-2 (L2) [0/90/45/-45]2S, respectively. These laminates were designed, such that the 0° layers are placed at a similar position in both the laminate systems by changing the other layers. During the test, load and displacement data was monitored online along with instantaneous number of constant load amplitude (CLA) fatigue cycles to calculate the stiffness degradation. Three load levels of 90%, 80%, and 70% of the ultimate flexure strength (UFS) were chosen for assessing the flexure fatigue behavior of the laminates. A few tests were also attempted under variable amplitude loads: (i) high amplitude cycles followed by low amplitude and (ii) low amplitude cycles followed by high amplitude to examine load sequence effect on fatigue life, if any, as compared to the fatigue life under CLA. It has been observed that the laminate L1 performs better under higher amplitudes, while the laminate L2 shows increased life under lower load and variable amplitudes. The results obtained in the form of data plots and failure modes, supported by microscopic images, are discussed in the paper.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81684694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this conference paper, nanoscale material property data and ASTM mode I interlaminar fracture results for three-phase buckypaper samples are presented and analyzed. Vacuum filtration and surfactant-free methods were used to manufacture buckypaper membranes. Epoxy infused buckypaper membranes were placed in front of the crack tip in a stitch bonded carbon fiber polymer matrix composite. Peak Force Quantitative Nanomechanical Mapping (PFQNM), using probes with nominal tip radius in the range of 5–8 nm were used. PFQNM characterized the interphase region between a three-phase sample of carbon monofilament, epoxy resin, and multi-walled carbon nanotube (MWCNT) buckypaper. This experiment captured reproducible nanoscale morphological, viscoelastic, elastic and energy properties of porous MWCNT buckypaper samples. An enlarged interphase region surrounding the CNT buckypaper was found. The buckypaper and epoxy interphase thickness was found to be 50nm, higher than the 10–40nm reported for epoxy and carbon monofilaments. The observed MWCNT structure provides explanation of the increased surface roughness compared to the smooth carbon monofilaments. The increased surface roughness likely improves mechanical interlocking with the epoxy of adjacent lamina. The nanoscale interphase and subsurface characterization data provide explanation for a change in crack propagation toughness. Buckypaper exhibited inhomogeneous properties at micrometer length scales.
{"title":"Nanoscale Interphase Characterization of Porous CNT Buckypaper Composites in Correlation to Interlaminar Mode I Fracture","authors":"M. Y. Fard, Jack Mester, A. Pensky","doi":"10.1115/IMECE2020-23618","DOIUrl":"https://doi.org/10.1115/IMECE2020-23618","url":null,"abstract":"\u0000 In this conference paper, nanoscale material property data and ASTM mode I interlaminar fracture results for three-phase buckypaper samples are presented and analyzed. Vacuum filtration and surfactant-free methods were used to manufacture buckypaper membranes. Epoxy infused buckypaper membranes were placed in front of the crack tip in a stitch bonded carbon fiber polymer matrix composite. Peak Force Quantitative Nanomechanical Mapping (PFQNM), using probes with nominal tip radius in the range of 5–8 nm were used. PFQNM characterized the interphase region between a three-phase sample of carbon monofilament, epoxy resin, and multi-walled carbon nanotube (MWCNT) buckypaper. This experiment captured reproducible nanoscale morphological, viscoelastic, elastic and energy properties of porous MWCNT buckypaper samples. An enlarged interphase region surrounding the CNT buckypaper was found. The buckypaper and epoxy interphase thickness was found to be 50nm, higher than the 10–40nm reported for epoxy and carbon monofilaments. The observed MWCNT structure provides explanation of the increased surface roughness compared to the smooth carbon monofilaments. The increased surface roughness likely improves mechanical interlocking with the epoxy of adjacent lamina. The nanoscale interphase and subsurface characterization data provide explanation for a change in crack propagation toughness. Buckypaper exhibited inhomogeneous properties at micrometer length scales.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77223617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-Hong Yin, Jin Jian, Can Yang, T. Lei, Tao Cheng
In the present work, the poly (vinylidene fluoride) composite filled with the lead zirconium titanate (PVDF/PZT) was numerically investigated focusing on the improvement of piezoelectric performance parameters. With a multi-scale simulation strategy, effects of the PZT fillers’ orientation and length on the electrical outputs of the piezoelectric energy collectors buried in the roads were systematically examined. Specifically, at the micro-scale, based on our previous research results, Comsol Multiphysics connected with Matlab was utilized to create the unit cell of piezoelectric composites. The simulation results showed that parameters of PZT nano-fillers greatly affect the piezoelectric coefficients. For the macro-scale simulation, a road energy collector with innovative symmetrical cantilever structure was designed, with piezoelectric constants obtained at micro-scale simulation as inputs. The correlation between the output voltage of the energy-collector and PZT parameters (i.e., orientation and length) was successfully developed by applying the vehicle’s axle-load. This work provides a way for tailoring the piezoelectric performance of the macro components (i.e., sensors) through adjusting the states of the fillers inside the piezoelectric composites.
{"title":"Piezoelectric Performance of PVDF Composites for Transportation Engineering: A Multi-Scale Simulation Study","authors":"Xiao-Hong Yin, Jin Jian, Can Yang, T. Lei, Tao Cheng","doi":"10.1115/IMECE2020-24549","DOIUrl":"https://doi.org/10.1115/IMECE2020-24549","url":null,"abstract":"\u0000 In the present work, the poly (vinylidene fluoride) composite filled with the lead zirconium titanate (PVDF/PZT) was numerically investigated focusing on the improvement of piezoelectric performance parameters. With a multi-scale simulation strategy, effects of the PZT fillers’ orientation and length on the electrical outputs of the piezoelectric energy collectors buried in the roads were systematically examined. Specifically, at the micro-scale, based on our previous research results, Comsol Multiphysics connected with Matlab was utilized to create the unit cell of piezoelectric composites. The simulation results showed that parameters of PZT nano-fillers greatly affect the piezoelectric coefficients. For the macro-scale simulation, a road energy collector with innovative symmetrical cantilever structure was designed, with piezoelectric constants obtained at micro-scale simulation as inputs. The correlation between the output voltage of the energy-collector and PZT parameters (i.e., orientation and length) was successfully developed by applying the vehicle’s axle-load. This work provides a way for tailoring the piezoelectric performance of the macro components (i.e., sensors) through adjusting the states of the fillers inside the piezoelectric composites.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75736775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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