Various brittle fractures have been found to occur at grain boundaries in polycrystalline materials. In thin film interconnections used for semiconductor devices, open failures caused by electro- and strain-induced migrations have been found to be dominated by porous random grain boundaries that consist of a lot of defects. Therefore, it is very important to explicate the dominant factors of the strength of a grain boundary in polycrystalline materials for assuring the safe and reliable operation of various products. In this study, both electron back-scatter diffraction (EBSD) analysis and a micro tensile test in a scanning electron microscope was applied to copper thin film which is used for interconnection of semiconductor devices in order to clarify the relationship between the strength and the crystallinity of a grain and a grain boundary quantitatively. Image quality (IQ) value obtained from the EBSD analysis, which indicates the average sharpness of the diffraction pattern (Kikuchi pattern) was applied to the crystallinity analysis. This IQ value indicates the total density of defects such as vacancies, dislocations, impurities, and local strain, in other words, the order of atom arrangement in the observed area in nano-scale. In the micro tensile test system, stress-strain curves of a single crystal specimen and a bicrystal specimen was measured quantitatively. Both transgranular and intergranular fracture modes were observed in the tested specimens with different IQ values. Based to the results of these experiments, it was found that there is the critical IQ value at which the fracture mode of the bicrystal specimen changes from brittle intergranular fracture at a grain boundary to ductile transgranular fracture in a grain. The strength of a grain boundary increases monotonically with IQ value because of the increase in the total number of rigid atomic bonding. On the other hand, the strength of a grain decreases monotonically with the increase of IQ value because the increase in the order of atom arrangement accelerates the movement of dislocations. Finally, it was clarified that the strength of a grain boundary and a grain changes drastically as a strong function of their crystallinity.
{"title":"Degradation of the Strength of a Grain and a Grain Boundary due to the Accumulation of the Structural Defects of Crystal","authors":"G. Zheng, Yifan Luo, H. Miura","doi":"10.1115/IMECE2018-87264","DOIUrl":"https://doi.org/10.1115/IMECE2018-87264","url":null,"abstract":"Various brittle fractures have been found to occur at grain boundaries in polycrystalline materials. In thin film interconnections used for semiconductor devices, open failures caused by electro- and strain-induced migrations have been found to be dominated by porous random grain boundaries that consist of a lot of defects. Therefore, it is very important to explicate the dominant factors of the strength of a grain boundary in polycrystalline materials for assuring the safe and reliable operation of various products.\u0000 In this study, both electron back-scatter diffraction (EBSD) analysis and a micro tensile test in a scanning electron microscope was applied to copper thin film which is used for interconnection of semiconductor devices in order to clarify the relationship between the strength and the crystallinity of a grain and a grain boundary quantitatively. Image quality (IQ) value obtained from the EBSD analysis, which indicates the average sharpness of the diffraction pattern (Kikuchi pattern) was applied to the crystallinity analysis. This IQ value indicates the total density of defects such as vacancies, dislocations, impurities, and local strain, in other words, the order of atom arrangement in the observed area in nano-scale. In the micro tensile test system, stress-strain curves of a single crystal specimen and a bicrystal specimen was measured quantitatively. Both transgranular and intergranular fracture modes were observed in the tested specimens with different IQ values.\u0000 Based to the results of these experiments, it was found that there is the critical IQ value at which the fracture mode of the bicrystal specimen changes from brittle intergranular fracture at a grain boundary to ductile transgranular fracture in a grain. The strength of a grain boundary increases monotonically with IQ value because of the increase in the total number of rigid atomic bonding. On the other hand, the strength of a grain decreases monotonically with the increase of IQ value because the increase in the order of atom arrangement accelerates the movement of dislocations. Finally, it was clarified that the strength of a grain boundary and a grain changes drastically as a strong function of their crystallinity.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116332695","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}
Max Rieger, B. Nagarajan, Mario Vollmer, P. Mertiny
Dispersing micro and nanoparticles into polymeric materials has proven to induce multifunctional properties in polymer composites, including their magnetic, electrical, thermal and mechanical characteristics. Adding carbon-based nanoparticle inclusions such as Graphene Nano-Platelets (GNP) to polymeric materials typically leads to thermal, electrical and mechanical property enhancements. Raising thermal conductivity by adding highly thermally conductive fillers particularly harbors great potential given diverse possible applications, such as in the electronics industry. In this study, the focus is on increasing the thermal conductivity of an epoxy by dispersing GNP in the pre-polymer. The influence of various process parameters such as filler loading, influence of swelling, use of solvent and additives, sonication time and amplitude, as well as curing cycle were determined. By means of a Design of Experiments approach the parameters which have the greatest effect on thermal conductivity enhancement were identified. Through this study a better understanding of the influence of process parameters was achieved in a qualitative and quantitative manner. The study further aids in selecting ideal process parameters for maximum thermal conductivity enhancements.
{"title":"Determination of Key Influencing Factors on Thermal Conductivity Enhancement of Graphene Nano-Platelets Reinforced Epoxy","authors":"Max Rieger, B. Nagarajan, Mario Vollmer, P. Mertiny","doi":"10.1115/IMECE2018-86847","DOIUrl":"https://doi.org/10.1115/IMECE2018-86847","url":null,"abstract":"Dispersing micro and nanoparticles into polymeric materials has proven to induce multifunctional properties in polymer composites, including their magnetic, electrical, thermal and mechanical characteristics. Adding carbon-based nanoparticle inclusions such as Graphene Nano-Platelets (GNP) to polymeric materials typically leads to thermal, electrical and mechanical property enhancements. Raising thermal conductivity by adding highly thermally conductive fillers particularly harbors great potential given diverse possible applications, such as in the electronics industry. In this study, the focus is on increasing the thermal conductivity of an epoxy by dispersing GNP in the pre-polymer. The influence of various process parameters such as filler loading, influence of swelling, use of solvent and additives, sonication time and amplitude, as well as curing cycle were determined. By means of a Design of Experiments approach the parameters which have the greatest effect on thermal conductivity enhancement were identified. Through this study a better understanding of the influence of process parameters was achieved in a qualitative and quantitative manner. The study further aids in selecting ideal process parameters for maximum thermal conductivity enhancements.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125668399","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}
Chris Ferri, Sydney Lizarazo, Michael Troise, P. Iglesias
In manufacturing processes, the cost of tooling contributes to a significant portion of operating costs. Several papers have been dedicated to various improvements on tool life, including monitoring the effect of temperature conditions and flood cooling. Flood cooling is not economical, so research has also been done to investigate minimum quantity lubrication and the effects of different additives, such as nanofluids. Another additive, ionic liquids, have become popular in tribological studies because they have unique properties that allow them to form ordered molecular structures, which is ideal in lubrication. Research has proven ionic liquids to be effective in reducing wear and friction coefficients. Currently, utilizing ionic liquids specifically to reduce tool wear has been almost exclusively limited to titanium and steel applications. The goal of this study is to improve tribological performance of the subtractive manufacturing process using ionic liquid add-ins to widely available machine shop coolants and oils. A series of reciprocating ball-on-flat experiments will be conducted using a 1.5mm diameter 250 Chrome Steel G25 ball and 6061-T6 aluminum disk to simulate cutting conditions often seen in manufacturing processes. 6061 Aluminum is an alloy commonly seen in machine shops and large-scale manufacturing scenarios because of its versatile material properties and wide availability. The tests were run at constant sliding distance, velocity and load. The lubricating mixtures were prepared by adding 5 wt % of a phosphonium based ionic liquid, Trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide ([THTDP][NTf2]), to the base fluids Trim Sol™ emulsion fluid and Mobilmet™ 766 high performance neat cutting oil. The addition of the ionic liquid to both base lubricants (oil and coolant) increased the friction coefficient (18.60% and 4.89%, respectively) while the wear volume was reduced (28.75% and 7.84%, respectively). The results for the oil provided evidence that the ionic liquid did have an effect to reduce wear, however, the same conclusion could not be drawn for the coolant.
{"title":"Ionic Liquids As Additives to Cutting Fluids to Reduce Machine Tool Friction and Wear","authors":"Chris Ferri, Sydney Lizarazo, Michael Troise, P. Iglesias","doi":"10.1115/IMECE2018-86810","DOIUrl":"https://doi.org/10.1115/IMECE2018-86810","url":null,"abstract":"In manufacturing processes, the cost of tooling contributes to a significant portion of operating costs. Several papers have been dedicated to various improvements on tool life, including monitoring the effect of temperature conditions and flood cooling. Flood cooling is not economical, so research has also been done to investigate minimum quantity lubrication and the effects of different additives, such as nanofluids. Another additive, ionic liquids, have become popular in tribological studies because they have unique properties that allow them to form ordered molecular structures, which is ideal in lubrication. Research has proven ionic liquids to be effective in reducing wear and friction coefficients. Currently, utilizing ionic liquids specifically to reduce tool wear has been almost exclusively limited to titanium and steel applications. The goal of this study is to improve tribological performance of the subtractive manufacturing process using ionic liquid add-ins to widely available machine shop coolants and oils. A series of reciprocating ball-on-flat experiments will be conducted using a 1.5mm diameter 250 Chrome Steel G25 ball and 6061-T6 aluminum disk to simulate cutting conditions often seen in manufacturing processes. 6061 Aluminum is an alloy commonly seen in machine shops and large-scale manufacturing scenarios because of its versatile material properties and wide availability. The tests were run at constant sliding distance, velocity and load. The lubricating mixtures were prepared by adding 5 wt % of a phosphonium based ionic liquid, Trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide ([THTDP][NTf2]), to the base fluids Trim Sol™ emulsion fluid and Mobilmet™ 766 high performance neat cutting oil. The addition of the ionic liquid to both base lubricants (oil and coolant) increased the friction coefficient (18.60% and 4.89%, respectively) while the wear volume was reduced (28.75% and 7.84%, respectively). The results for the oil provided evidence that the ionic liquid did have an effect to reduce wear, however, the same conclusion could not be drawn for the coolant.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131263438","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}
By using the internal state variable (ISV) theory (Horstemeyer and Bammann, 2010), we developed a finite deformation anisotropic and temperature dependent constitutive model to predict elastoviscoplasticity and progressive damage behavior of short fiber reinforced polymer (SFRP) composites. In this model, the SFRP is considered as a simple anisotropic equivalent medium (lamina), and the rate dependent plastic behavior of the SFRP is captured with the help of three physically-based ISVs. A second-order damage tensor is introduced to describe the anisotropic damage state of the SFRP and the tensorial damage evolution equations are used based on the damage mechanism of micro voids/cracks nucleation, growth and coalescence. The constitutive model developed herein arises employing standard postulates of continuum mechanics with the kinematics, thermodynamics, and kinetics being internally consistent. The developed model is then calibrated to a 35 wt% glass fiber reinforced polyamide 66 (PA66GF-35) for future numerical analyses.
{"title":"An Elastothermoviscoplasticity Anisotropic Damage Model for Short Fiber Reinforced Polymer Composites","authors":"Ge He, Yucheng Liu, D. Bammann, M. Horstemeyer","doi":"10.1115/IMECE2018-86286","DOIUrl":"https://doi.org/10.1115/IMECE2018-86286","url":null,"abstract":"By using the internal state variable (ISV) theory (Horstemeyer and Bammann, 2010), we developed a finite deformation anisotropic and temperature dependent constitutive model to predict elastoviscoplasticity and progressive damage behavior of short fiber reinforced polymer (SFRP) composites. In this model, the SFRP is considered as a simple anisotropic equivalent medium (lamina), and the rate dependent plastic behavior of the SFRP is captured with the help of three physically-based ISVs. A second-order damage tensor is introduced to describe the anisotropic damage state of the SFRP and the tensorial damage evolution equations are used based on the damage mechanism of micro voids/cracks nucleation, growth and coalescence. The constitutive model developed herein arises employing standard postulates of continuum mechanics with the kinematics, thermodynamics, and kinetics being internally consistent. The developed model is then calibrated to a 35 wt% glass fiber reinforced polyamide 66 (PA66GF-35) for future numerical analyses.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131126776","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}
M. Abshirini, Mohammad Charara, Yingtao Liu, M. Saha, M. Altan
This paper presents the additive manufacturing of electrically conductive polydimethylsiloxane (PDMS) nanocomposites for in-situ strain sensing applications. A straight line of pristine PDMS was first 3D printed on a thin PDMS substrate using an in-house modified 3D printer. Carbon nanotubes (CNTs) were uniformly sprayed on top of uncured PDMS lines. An additional layer of PDMS was then applied on top of CNTs to form a thin protective coating. The 3D printed PDMS/CNT nanocomposites were characterized using a scanning electron microscope (SEM) to validate the thickness, CNT distribution, and microstructural features of the sensor cross-section. The strain sensing capability of the nanocomposites was investigated under tensile cyclic loading at different strain rates and maximum strains. Sensing experiments indicate that under cyclic loading, the changes in piezo resistivity mimic, both, the changes in the applied load and the measured material strain with high fidelity. Due to the high flexibility of PDMS, the 3D printed sensors have potential applications in real-time load sensing and structural health monitoring of complex flexible structures.
{"title":"Additive Manufacturing of Polymer Nanocomposites With In-Situ Strain Sensing Capability","authors":"M. Abshirini, Mohammad Charara, Yingtao Liu, M. Saha, M. Altan","doi":"10.1115/IMECE2018-86263","DOIUrl":"https://doi.org/10.1115/IMECE2018-86263","url":null,"abstract":"This paper presents the additive manufacturing of electrically conductive polydimethylsiloxane (PDMS) nanocomposites for in-situ strain sensing applications. A straight line of pristine PDMS was first 3D printed on a thin PDMS substrate using an in-house modified 3D printer. Carbon nanotubes (CNTs) were uniformly sprayed on top of uncured PDMS lines. An additional layer of PDMS was then applied on top of CNTs to form a thin protective coating. The 3D printed PDMS/CNT nanocomposites were characterized using a scanning electron microscope (SEM) to validate the thickness, CNT distribution, and microstructural features of the sensor cross-section. The strain sensing capability of the nanocomposites was investigated under tensile cyclic loading at different strain rates and maximum strains. Sensing experiments indicate that under cyclic loading, the changes in piezo resistivity mimic, both, the changes in the applied load and the measured material strain with high fidelity. Due to the high flexibility of PDMS, the 3D printed sensors have potential applications in real-time load sensing and structural health monitoring of complex flexible structures.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124818208","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}
Atomistic simulations play an important role in the material analysis and design by being rooted in the accurate first principles methods that free from empirical parameters and phenomenological models. However, successful applications of MD simulations largely depend on the availability of efficient and accurate force field potentials used for describing the interatomic interactions. As a powerful tool revolutionizing many areas in science and technology, machine learning techniques have gained growing attentions in the field of material science and engineering due to their potentials to accelerate the material discovery through their applications in surrogate model assisted material design. Despite tremendous advantages of employing machine learning techniques for the development of force field potentials as compared to conventional approaches, the uncertainty involved in the machine learning interpolated atomic potential energy surface has not drew much attention although it is an important issue. In this paper, the uncertainty quantification study is performed for the machine learning interpolated atomic potentials, and applied to the titanium dioxide (TiO2), an industrially relevant and well-studies material. The study results indicated that quantifying uncertainties is an indispensable task that must be performed along with the atomistic simulation process for a successful application of the machine learning based force field potentials.
{"title":"Uncertainty Quantification of Artificial Neural Network Based Machine Learning Potentials","authors":"Yumeng Li, Weirong Xiao, Pingfeng Wang","doi":"10.1115/IMECE2018-88071","DOIUrl":"https://doi.org/10.1115/IMECE2018-88071","url":null,"abstract":"Atomistic simulations play an important role in the material analysis and design by being rooted in the accurate first principles methods that free from empirical parameters and phenomenological models. However, successful applications of MD simulations largely depend on the availability of efficient and accurate force field potentials used for describing the interatomic interactions. As a powerful tool revolutionizing many areas in science and technology, machine learning techniques have gained growing attentions in the field of material science and engineering due to their potentials to accelerate the material discovery through their applications in surrogate model assisted material design. Despite tremendous advantages of employing machine learning techniques for the development of force field potentials as compared to conventional approaches, the uncertainty involved in the machine learning interpolated atomic potential energy surface has not drew much attention although it is an important issue. In this paper, the uncertainty quantification study is performed for the machine learning interpolated atomic potentials, and applied to the titanium dioxide (TiO2), an industrially relevant and well-studies material. The study results indicated that quantifying uncertainties is an indispensable task that must be performed along with the atomistic simulation process for a successful application of the machine learning based force field potentials.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"112 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116637996","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}
Liquid crystal polymers (LCP’s) comprise a class of melt-processable materials that derive specialized mechanical, chemical, and electrical properties from long-range molecular ordering. This unique microstructure gives rise to anisotropic bulk behavior that can be problematic for industrial applications, and thus the ability to model the orientation state in the polymer is necessary for the design of isotropic material manufacturing processes. Previous efforts to model LCP directionality have been primarily restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the director field in full-scale melt-processing set-ups, specifically cast film extrusion, to predict the bulk material orientation state. The hybrid approach utilizes separate simulations for the polymer flow with commercial computational fluid dynamics (CFD) software, and the material directionality through a user-defined post-processing script. Wide-angle x-ray scattering (WAXS) is used to experimentally validate the simulated directionality during extrusion processing. It is shown that the model is capable of predicting both the direction and degree of orientation in the polymer resulting from processing, and the model produces strong agreement with experimental measurement of the polymer orientation state.
{"title":"Simulation of Liquid Crystal Polymer Directionality During Cast Film Extrusion","authors":"A. Sullivan, A. Saigal, M. Zimmerman","doi":"10.1115/IMECE2018-86855","DOIUrl":"https://doi.org/10.1115/IMECE2018-86855","url":null,"abstract":"Liquid crystal polymers (LCP’s) comprise a class of melt-processable materials that derive specialized mechanical, chemical, and electrical properties from long-range molecular ordering. This unique microstructure gives rise to anisotropic bulk behavior that can be problematic for industrial applications, and thus the ability to model the orientation state in the polymer is necessary for the design of isotropic material manufacturing processes. Previous efforts to model LCP directionality have been primarily restricted to structured grids and simple geometries that demonstrate the underlying theory, but fall short of simulating realistic manufacturing geometries. In this investigation, a practical methodology is proposed to simulate the director field in full-scale melt-processing set-ups, specifically cast film extrusion, to predict the bulk material orientation state. The hybrid approach utilizes separate simulations for the polymer flow with commercial computational fluid dynamics (CFD) software, and the material directionality through a user-defined post-processing script. Wide-angle x-ray scattering (WAXS) is used to experimentally validate the simulated directionality during extrusion processing. It is shown that the model is capable of predicting both the direction and degree of orientation in the polymer resulting from processing, and the model produces strong agreement with experimental measurement of the polymer orientation state.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114205360","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}
David J. Traina, T. Ekstrom, Owen F. Van Valkenburgh, Jean-Paul R. Wallis, David S. Schulman, Emily R. Mather, Nathan K. Yasuda, F. Shih
The advent of additive manufacturing allows for the design of complex 3D geometries that would otherwise be difficult to manufacture using traditional processes. Stereolithographic printing of geometrically reinforced structures gives promise for tunable energy-absorbing composite materials for impact applications. These materials may be suitable for applications in personal sport protection equipment such as knee-pads or helmets. The flexible nature of additive manufacturing can be easily scaled and modified to serve a variety of impact loading applications. In the present study, a three-dimensional nested array of ridged polymeric mesh with tiered high-temperature UV-cured polymer were embedded in a polyurethane matrix to form a new class of functional composite materials designed for multi-use low velocity impact events, and a single-use high velocity or high force impact event. The reinforcements were designed to absorb impact energy by the sequential bending, bucking, and failure of the layers of nested reinforcing members. The energy absorption capacity is further enhanced by the connective elastomer matrix which serves to retain the fractured mesh structure after initial breakage. The peak load is maintained at a relatively modest level while maximizing absorbed energy. Quasi-static loading tests were conducted to measure the peak load, total energy absorbing capability of the material. The energy absorption capability is measured using force-displacement plots and multiple interactions of material combination of reinforcement ring arrays. Tests with and without elastomer matrix, were conducted to understand peak load minimization and energy absorption character of the material.
{"title":"A Three-Dimensional Nested Reinforcing Mesh in Elastomers for Crashworthy Applications","authors":"David J. Traina, T. Ekstrom, Owen F. Van Valkenburgh, Jean-Paul R. Wallis, David S. Schulman, Emily R. Mather, Nathan K. Yasuda, F. Shih","doi":"10.1115/IMECE2018-88471","DOIUrl":"https://doi.org/10.1115/IMECE2018-88471","url":null,"abstract":"The advent of additive manufacturing allows for the design of complex 3D geometries that would otherwise be difficult to manufacture using traditional processes. Stereolithographic printing of geometrically reinforced structures gives promise for tunable energy-absorbing composite materials for impact applications. These materials may be suitable for applications in personal sport protection equipment such as knee-pads or helmets. The flexible nature of additive manufacturing can be easily scaled and modified to serve a variety of impact loading applications. In the present study, a three-dimensional nested array of ridged polymeric mesh with tiered high-temperature UV-cured polymer were embedded in a polyurethane matrix to form a new class of functional composite materials designed for multi-use low velocity impact events, and a single-use high velocity or high force impact event. The reinforcements were designed to absorb impact energy by the sequential bending, bucking, and failure of the layers of nested reinforcing members. The energy absorption capacity is further enhanced by the connective elastomer matrix which serves to retain the fractured mesh structure after initial breakage. The peak load is maintained at a relatively modest level while maximizing absorbed energy. Quasi-static loading tests were conducted to measure the peak load, total energy absorbing capability of the material. The energy absorption capability is measured using force-displacement plots and multiple interactions of material combination of reinforcement ring arrays. Tests with and without elastomer matrix, were conducted to understand peak load minimization and energy absorption character of the material.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123216699","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}
Hong Guo, Steven Keil, J. Ackerman, I. Puchades, B. Landi, P. Iglesias
A significant amount of energy dissipates from frictional losses of moving components in machinery and devices in industry. This contact friction leads to the wear and eventual failure of industrial mechanical components over extended time through adhesion, abrasion, fatigue, or corrosion. Frictional losses could be mitigated by utilizing more effective lubricants, which would allow the translating surfaces to slide over one another more fluently. There is reason to study eco-friendly alternatives over traditional lubricants to reduce negative impact to the environment. The implementation of Ionic Liquids (ILs) as additives to oil-based lubricants is a development in tribology with the potential to lower the friction coefficient and reduce wear. When carbon nanotubes are dispersed into these ionic liquids, the reduction of losses due to friction and wear can be even greater. In this experiment, single-walled carbon nanotubes (SWCNTs) of four concentrations, 0 wt.%, 0.01 wt.%, 0.02 wt.%, and 0.03 wt.% were dispersed in a room temperature ionic liquid, Trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl) phosphinate, or [THTDP][Phos] for short, to form four homogeneous mixtures. Then, each mixture was added in 1 wt.% to a base vegetable oil. Friction tests were also conducted with pure vegetable oil for comparative purposes. The experiments consist of a pin-on-disk rotational tribometer and a ball-on-flat reciprocating tribometer both applying a steel-steel (AISI 52100) contact to evaluate the lubricating ability of combining SWCNTs and ILs as lubricant additives. The load, speed, wear radius, sliding distance, and duration of the experiment were held constant to isolate lubrication as the experimental parameter. Optical microscopy (OM), thermogravimetric analysis (TGA), and viscometer analysis were utilized after experimentation to analyze and discuss the wear mechanisms of the worn surfaces. Results differed between rotational and translational experiments, with the rotational results yielding a decrease of 14.21% in wear loss with the VO+1%[THTDP][Phos] lubricant. The translational results yielded a continuous decrease in wear loss with the increase in SWCNT wt.%.
{"title":"The Effects of Single-Walled Carbon Nanotubes and Ionic Liquids in Reduction of Friction and Wear","authors":"Hong Guo, Steven Keil, J. Ackerman, I. Puchades, B. Landi, P. Iglesias","doi":"10.1115/IMECE2018-86703","DOIUrl":"https://doi.org/10.1115/IMECE2018-86703","url":null,"abstract":"A significant amount of energy dissipates from frictional losses of moving components in machinery and devices in industry. This contact friction leads to the wear and eventual failure of industrial mechanical components over extended time through adhesion, abrasion, fatigue, or corrosion. Frictional losses could be mitigated by utilizing more effective lubricants, which would allow the translating surfaces to slide over one another more fluently. There is reason to study eco-friendly alternatives over traditional lubricants to reduce negative impact to the environment. The implementation of Ionic Liquids (ILs) as additives to oil-based lubricants is a development in tribology with the potential to lower the friction coefficient and reduce wear. When carbon nanotubes are dispersed into these ionic liquids, the reduction of losses due to friction and wear can be even greater. In this experiment, single-walled carbon nanotubes (SWCNTs) of four concentrations, 0 wt.%, 0.01 wt.%, 0.02 wt.%, and 0.03 wt.% were dispersed in a room temperature ionic liquid, Trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl) phosphinate, or [THTDP][Phos] for short, to form four homogeneous mixtures. Then, each mixture was added in 1 wt.% to a base vegetable oil. Friction tests were also conducted with pure vegetable oil for comparative purposes. The experiments consist of a pin-on-disk rotational tribometer and a ball-on-flat reciprocating tribometer both applying a steel-steel (AISI 52100) contact to evaluate the lubricating ability of combining SWCNTs and ILs as lubricant additives. The load, speed, wear radius, sliding distance, and duration of the experiment were held constant to isolate lubrication as the experimental parameter. Optical microscopy (OM), thermogravimetric analysis (TGA), and viscometer analysis were utilized after experimentation to analyze and discuss the wear mechanisms of the worn surfaces. Results differed between rotational and translational experiments, with the rotational results yielding a decrease of 14.21% in wear loss with the VO+1%[THTDP][Phos] lubricant. The translational results yielded a continuous decrease in wear loss with the increase in SWCNT wt.%.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121040300","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}
Lubricants play a vital role in improving energy efficiency and reducing friction in any type of frictional contact. The automotive industry is facing strict regulations in terms of emissions from the petroleum fuel. Strict government norms are compelling automotive manufacturers to push their technological limits to improve the fuel economy and emissions from their vehicles. Improving the efficiency of the engine will ultimately result in saving fuel thus improving the fuel economy of the engine. Concerning energy consumption; 33% of the fuel energy developed by combustion of fuel is dissipated to overcome the friction losses in the vehicle [1]. Out of this, 11.56% of the total fuel energy is lost in engine system. The distribution of this 11.56% fuel energy lost in engine system includes 3.5% consumed in bearings, 1.16% in pumping and hydraulic viscous losses, 5.2% and 1.73% consumed in piston assembly and valve train respectively [1]. If we consider losses only in bearings, piston assembly and valve train it results in 10.4% energy loss as compared to the total energy generated by the fuel. In the last decade, ionic liquids have shown potential as lubricants and lubricant additives. This study focusses on the use ionic liquids as additives for friction and wear reduction resulting in energy conservation in an internal combustion engine. In this work, the contact between piston ring and cylinder wall was simulated using a ball-on-flat tribometer. Most of the engine oils are based on mineral oils and results showed that adding 1% of the ionic liquid to mineral oil reduced friction loses by 27% [2], which corresponds to conserving 2.8% of fuel energy if just the frictional loss in piston assembly, valve train and bearing are considered. In the United States, there are 253 million vehicles on average consuming 678 gallons of fuel per year [3], the use of ionic liquid can save an estimated 4.8 billion gallons of fuel per year, which results in estimated saving of 11.56 billion dollars.
{"title":"Estimation of Energy Conservation in Internal Combustion Engine Vehicles Using Ionic Liquid As an Additive","authors":"Sameer Magar, Hong Guo, P. Iglesias","doi":"10.1115/IMECE2018-87002","DOIUrl":"https://doi.org/10.1115/IMECE2018-87002","url":null,"abstract":"Lubricants play a vital role in improving energy efficiency and reducing friction in any type of frictional contact. The automotive industry is facing strict regulations in terms of emissions from the petroleum fuel. Strict government norms are compelling automotive manufacturers to push their technological limits to improve the fuel economy and emissions from their vehicles. Improving the efficiency of the engine will ultimately result in saving fuel thus improving the fuel economy of the engine. Concerning energy consumption; 33% of the fuel energy developed by combustion of fuel is dissipated to overcome the friction losses in the vehicle [1]. Out of this, 11.56% of the total fuel energy is lost in engine system. The distribution of this 11.56% fuel energy lost in engine system includes 3.5% consumed in bearings, 1.16% in pumping and hydraulic viscous losses, 5.2% and 1.73% consumed in piston assembly and valve train respectively [1]. If we consider losses only in bearings, piston assembly and valve train it results in 10.4% energy loss as compared to the total energy generated by the fuel. In the last decade, ionic liquids have shown potential as lubricants and lubricant additives. This study focusses on the use ionic liquids as additives for friction and wear reduction resulting in energy conservation in an internal combustion engine. In this work, the contact between piston ring and cylinder wall was simulated using a ball-on-flat tribometer. Most of the engine oils are based on mineral oils and results showed that adding 1% of the ionic liquid to mineral oil reduced friction loses by 27% [2], which corresponds to conserving 2.8% of fuel energy if just the frictional loss in piston assembly, valve train and bearing are considered. In the United States, there are 253 million vehicles on average consuming 678 gallons of fuel per year [3], the use of ionic liquid can save an estimated 4.8 billion gallons of fuel per year, which results in estimated saving of 11.56 billion dollars.","PeriodicalId":119074,"journal":{"name":"Volume 12: Materials: Genetics to Structures","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116494961","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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