Sipan Liu, Md. Didarul Islam, Z. Ku, A. Urbas, J. Derov, D. Boyd, Woohong Kim, J. Sanghera, J. Ryu
This study investigates the embedded nanoparticles’ morphology and distribution effects on the effective refractive index (RI) of composite. The study is based on the FEA model for the Fabry-Pérot interference cavity made from the nanocomposite film. The composites’ effective RI can be derived from the simulation reflection spectrum. In constant particle volume fraction condition, the embedded particles with a larger diameter, locating at the region with high electric field and having longer side length along the electric field oscillating direction, are identified as the factors to reinforce the effective RI. For 4 μm incident light-wave, as controlling the diameter from 24.8 nm to 212 nm, distribution from middle-gathered (high electric field region) to top-bottom gathered (low electric field region), and the rectangular cylinder particle shortest side along electric field oscillating direction to longest side along electric field oscillating direction, the effective RI increasing from 1.687 to 1.719, 1.638 to 1.745 and 1.66 to 1.901, respectively. The underlying RI shifting principle is recognized from the light scattering loss by embedded nanoparticles. This discovering provides one novel idea for next-generation real-time RI tuning structure and device.
{"title":"Novel Nanocomposite Refractive Index Tuning Mechanism Based on Controlling Embedded Particle Morphology","authors":"Sipan Liu, Md. Didarul Islam, Z. Ku, A. Urbas, J. Derov, D. Boyd, Woohong Kim, J. Sanghera, J. Ryu","doi":"10.1115/imece2021-70064","DOIUrl":"https://doi.org/10.1115/imece2021-70064","url":null,"abstract":"\u0000 This study investigates the embedded nanoparticles’ morphology and distribution effects on the effective refractive index (RI) of composite. The study is based on the FEA model for the Fabry-Pérot interference cavity made from the nanocomposite film. The composites’ effective RI can be derived from the simulation reflection spectrum. In constant particle volume fraction condition, the embedded particles with a larger diameter, locating at the region with high electric field and having longer side length along the electric field oscillating direction, are identified as the factors to reinforce the effective RI. For 4 μm incident light-wave, as controlling the diameter from 24.8 nm to 212 nm, distribution from middle-gathered (high electric field region) to top-bottom gathered (low electric field region), and the rectangular cylinder particle shortest side along electric field oscillating direction to longest side along electric field oscillating direction, the effective RI increasing from 1.687 to 1.719, 1.638 to 1.745 and 1.66 to 1.901, respectively. The underlying RI shifting principle is recognized from the light scattering loss by embedded nanoparticles. This discovering provides one novel idea for next-generation real-time RI tuning structure and device.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74622870","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 effect of cyclic corrosion on the static performance of multi-material double lap joints is investigated. Carbon-Fiber-Reinforced thermoplastic composite substrates are joined to Aluminum substrates using bonding-only, bolting-only, or by hybrid bonding-and-bolting methods. Polyurethane-based or epoxy-based structural adhesives are used. Surface roughness is maintained constant and evaluated with an optical profilometer. The quasi-static performance of baseline joints is assessed, and the results from the various joining methods are compared. Cyclic corrosion testing of Double Lap joints is performed in accordance with a GMW14872 3-stage laboratory standards for 30 one-full-day cycles. Quasi-static lap shear tests of test samples are performed at various stages of corrosion cycling, and progressive strength degradation is observed for bonded-only and hybrid bonded-and-bolted joints. Bolted-only joints do not show significant performance loss. Results, discussion, and conclusions are provided.
{"title":"Effect of Cyclic Corrosion and Joining Method on the Strength of Multimaterial Double Lap Joints","authors":"Marco Gerini Romagnoli, Chao Yang, S. Nassar","doi":"10.1115/imece2021-71154","DOIUrl":"https://doi.org/10.1115/imece2021-71154","url":null,"abstract":"\u0000 The effect of cyclic corrosion on the static performance of multi-material double lap joints is investigated. Carbon-Fiber-Reinforced thermoplastic composite substrates are joined to Aluminum substrates using bonding-only, bolting-only, or by hybrid bonding-and-bolting methods. Polyurethane-based or epoxy-based structural adhesives are used. Surface roughness is maintained constant and evaluated with an optical profilometer. The quasi-static performance of baseline joints is assessed, and the results from the various joining methods are compared. Cyclic corrosion testing of Double Lap joints is performed in accordance with a GMW14872 3-stage laboratory standards for 30 one-full-day cycles. Quasi-static lap shear tests of test samples are performed at various stages of corrosion cycling, and progressive strength degradation is observed for bonded-only and hybrid bonded-and-bolted joints. Bolted-only joints do not show significant performance loss. Results, discussion, and conclusions are provided.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81526479","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}
Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. The properties of metal foam are so diverse that they can be tailored to suit the particular need, hence the study of metal foams has become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. Most of the production methods cannot be widely utilized because of difficult process control and high production costs. One of the most economical ways to produce metal foam is adopting conventional electro deposition technique. The electro deposition technique starts from first metalizing the non-conducting polymeric foam and then electrically depositing metal onto this metallized precursor foam with open cells and later the precursor is removed by the sintering process. The main hindrance in this process is that foam being multi layered, a uniform deposition of the metal in the inner layers of the foam was not achieved. After sintering it was found that the foam sample turned out hollow at the center, due to lack or very less deposition of the metal. Experiments aiming to overcome this problem of non-uniform deposition of the metal in the inner layers of the precursor were conducted. It was found that mechanical agitation in the form of low frequency ultrasound promoted the uniform electro deposition throughout the metalized multilayered precursor. Finally, desired strength foam was produced.
{"title":"Ultrasound Assisted Production of Metal Foam From Polyurethane Precursor","authors":"Asima Zahoor, A. Mourad","doi":"10.1115/imece2021-73192","DOIUrl":"https://doi.org/10.1115/imece2021-73192","url":null,"abstract":"\u0000 Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. The properties of metal foam are so diverse that they can be tailored to suit the particular need, hence the study of metal foams has become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. Most of the production methods cannot be widely utilized because of difficult process control and high production costs. One of the most economical ways to produce metal foam is adopting conventional electro deposition technique. The electro deposition technique starts from first metalizing the non-conducting polymeric foam and then electrically depositing metal onto this metallized precursor foam with open cells and later the precursor is removed by the sintering process. The main hindrance in this process is that foam being multi layered, a uniform deposition of the metal in the inner layers of the foam was not achieved. After sintering it was found that the foam sample turned out hollow at the center, due to lack or very less deposition of the metal. Experiments aiming to overcome this problem of non-uniform deposition of the metal in the inner layers of the precursor were conducted. It was found that mechanical agitation in the form of low frequency ultrasound promoted the uniform electro deposition throughout the metalized multilayered precursor. Finally, desired strength foam was produced.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85086589","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}
Polymeric materials are composed of chains of molecules known as monomers which are held together by secondary bonds. Amorphous polymers have a glass transition temperature above which their behavior transitions from glassy to viscoelastic, meaning they act like both a viscous liquid and an elastic solid. This concept may seem familiar to anyone who has used Silly Putty®; bouncing a ball of Silly Putty causes the material to behave elastically whereas it will flow into a puddle if left on a table overnight. Time temperature superposition (TTS) describes the dependence of viscoelastic mechanical properties on time and temperature. Repeating the Silly Putty experiment at a different temperature will change how long it takes to reach the same end mechanical property. The Williams-Landel-Ferry (WLF) equation empirically defines the relationship between a temperature shift and a shift in the timescale for a specific material property. It has been widely used for materials undergoing low rates of strain (e.g. creep, stress relaxation), but it applies to any property of viscoelastic behavior. This paper examines modeling the temperature-dependent impact behavior of polymers based on the WLF equation. Although polymers experience viscoelastic behavior for an incredibly short time prior to fracture, the strong temperature dependence and past literature suggest the validity of the WLF equation to higher rates of strain as demonstrated herein for the energy absorption of acrylonitrile-butadiene-styrene (ABS) undergoing high-velocity multiaxial impact tests.
{"title":"Temperature-Dependent Impact Properties of ABS Polymer","authors":"Max Kratzok, A. Saigal, M. Zimmerman","doi":"10.1115/imece2021-71382","DOIUrl":"https://doi.org/10.1115/imece2021-71382","url":null,"abstract":"\u0000 Polymeric materials are composed of chains of molecules known as monomers which are held together by secondary bonds. Amorphous polymers have a glass transition temperature above which their behavior transitions from glassy to viscoelastic, meaning they act like both a viscous liquid and an elastic solid. This concept may seem familiar to anyone who has used Silly Putty®; bouncing a ball of Silly Putty causes the material to behave elastically whereas it will flow into a puddle if left on a table overnight.\u0000 Time temperature superposition (TTS) describes the dependence of viscoelastic mechanical properties on time and temperature. Repeating the Silly Putty experiment at a different temperature will change how long it takes to reach the same end mechanical property. The Williams-Landel-Ferry (WLF) equation empirically defines the relationship between a temperature shift and a shift in the timescale for a specific material property. It has been widely used for materials undergoing low rates of strain (e.g. creep, stress relaxation), but it applies to any property of viscoelastic behavior.\u0000 This paper examines modeling the temperature-dependent impact behavior of polymers based on the WLF equation. Although polymers experience viscoelastic behavior for an incredibly short time prior to fracture, the strong temperature dependence and past literature suggest the validity of the WLF equation to higher rates of strain as demonstrated herein for the energy absorption of acrylonitrile-butadiene-styrene (ABS) undergoing high-velocity multiaxial impact tests.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82846410","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}
P. Marashizadeh, M. Abshirini, M. Saha, Liangliang Huang, Yingtao Liu
This paper reports a molecular dynamics (MD) simulation study for evaluating the interfacial properties of ZnO nanowire (NW)/carbon fiber reinforced polymer (CFRP) hybrid composites. Molecular structures of the hybrid composite components, including cross-linked epoxy, graphene sheet representing carbon fiber surface, and ZnO NW are simulated. A representative volume element (RVE) is modeled at the nanoscale containing a ZnO NW vertically aligned on the carbon fiber surface and embedded in the epoxy matrix. Normal displacement load is applied to the carbon fiber sheet to separate it from the ZnO NW perpendicular to the fiber sheet. The traction-separation properties of the interface between fiber and the enhanced matrix are evaluated. The cohesive parameters, including the interfacial strength and the cohesive energy in the ZnO NW hybrid model, are compared with the bare model (fiber and epoxy). The MD simulation results show a 98% improvement in the cohesive energy and 130% improvement in interfacial strength of the hybrid CFRP composites. This study demonstrates the promising effect of aligning ZnO on the fibers for enhancing fiber-matrix adhesion.
{"title":"Atomistic Simulation of Interface Effects in Hybrid Carbon Fiber Reinforced Polymer Composites Incorporating ZnO Nanowires","authors":"P. Marashizadeh, M. Abshirini, M. Saha, Liangliang Huang, Yingtao Liu","doi":"10.1115/imece2021-70772","DOIUrl":"https://doi.org/10.1115/imece2021-70772","url":null,"abstract":"\u0000 This paper reports a molecular dynamics (MD) simulation study for evaluating the interfacial properties of ZnO nanowire (NW)/carbon fiber reinforced polymer (CFRP) hybrid composites. Molecular structures of the hybrid composite components, including cross-linked epoxy, graphene sheet representing carbon fiber surface, and ZnO NW are simulated. A representative volume element (RVE) is modeled at the nanoscale containing a ZnO NW vertically aligned on the carbon fiber surface and embedded in the epoxy matrix. Normal displacement load is applied to the carbon fiber sheet to separate it from the ZnO NW perpendicular to the fiber sheet. The traction-separation properties of the interface between fiber and the enhanced matrix are evaluated. The cohesive parameters, including the interfacial strength and the cohesive energy in the ZnO NW hybrid model, are compared with the bare model (fiber and epoxy). The MD simulation results show a 98% improvement in the cohesive energy and 130% improvement in interfacial strength of the hybrid CFRP composites. This study demonstrates the promising effect of aligning ZnO on the fibers for enhancing fiber-matrix adhesion.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79739221","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}
Ashby West, Garrett Venable, M. Flanagan, Evan Harris, B. Davis, F. T. Davidson, J. Hanus
The development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel, which could result in training constraints and possibly expensive upgrades to improve the safety of existing facilities. New training ammunition manufactured from novel structural materials are needed to allow for the safe, continued use of live-fire shoot house facilities. The goal of this project is to characterize a sintered metal powder and fit a suitable constitutive model for simulation in support of numerical design. A pressed and sintered blend of copper-tin was selected as a suitable representative material for this application. Samples were tested in uniaxial compression under quasi-static conditions and elevated temperatures. Dynamic compression testing at strain rates up to approximately 105 s−1 was conducted using a split-Hopkinson bar. The results of these tests were then used to fit Johnson-Cook and Zerilli-Armstrong strength models to the test data. The models were fit by selecting points from test data at different strain rates and elevated temperatures. This system of equations was then solved for each model while using the same test data to ensure a fair comparison of the results. A Mie-Gruneisen equation of state for the material was estimated using a rule of mixtures and existing shock and particle velocity data. Taylor cylinder tests were conducted and the rate of change in length was measured using high-speed video. Simulation of the Taylor tests was conducted using the developed strength and equation of state model and compared to the experimental results for model validation and comparison. Both the Johnson-Cook and Zerilli-Armstrong models resulted in less than 1% error of the Taylor cylinder results before material fracture. Further development of a fracture model for this material is recommended for use in high strain rate modeling applications.
{"title":"Constitutive Modeling and Validation of Sintered Metal Powders Subjected to Large Strains and High Strain Rates","authors":"Ashby West, Garrett Venable, M. Flanagan, Evan Harris, B. Davis, F. T. Davidson, J. Hanus","doi":"10.1115/imece2021-71461","DOIUrl":"https://doi.org/10.1115/imece2021-71461","url":null,"abstract":"\u0000 The development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel, which could result in training constraints and possibly expensive upgrades to improve the safety of existing facilities. New training ammunition manufactured from novel structural materials are needed to allow for the safe, continued use of live-fire shoot house facilities. The goal of this project is to characterize a sintered metal powder and fit a suitable constitutive model for simulation in support of numerical design. A pressed and sintered blend of copper-tin was selected as a suitable representative material for this application. Samples were tested in uniaxial compression under quasi-static conditions and elevated temperatures. Dynamic compression testing at strain rates up to approximately 105 s−1 was conducted using a split-Hopkinson bar. The results of these tests were then used to fit Johnson-Cook and Zerilli-Armstrong strength models to the test data. The models were fit by selecting points from test data at different strain rates and elevated temperatures. This system of equations was then solved for each model while using the same test data to ensure a fair comparison of the results. A Mie-Gruneisen equation of state for the material was estimated using a rule of mixtures and existing shock and particle velocity data. Taylor cylinder tests were conducted and the rate of change in length was measured using high-speed video. Simulation of the Taylor tests was conducted using the developed strength and equation of state model and compared to the experimental results for model validation and comparison. Both the Johnson-Cook and Zerilli-Armstrong models resulted in less than 1% error of the Taylor cylinder results before material fracture. Further development of a fracture model for this material is recommended for use in high strain rate modeling applications.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89434849","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}
This paper reports a fast and straightforward method for controlling the pore size distribution and mechanical properties of porous polydimethylsiloxane (PDMS) structures. The solvent evaporation-induced phase separation is implemented for the fabrication of absorbent PDMS sheets. The ternary polymer solution containing PDMS, water (nonsolvent), and three different solvents are prepared. Tetrahydrofuran, Heptane, and Toluene are the solvents explored in this study. The stepping heat treatment is applied to the sample to control the solvent evaporation and trigger the phase separation. The pore morphology and pore size distribution are explored using the scanning electron microscope images captured from the internal surface. The results demonstrate that the pore microstructure is sensitive to the solvent used in polymer solution preparation. Besides, the mechanical properties of the porous PDMS sheets are characterized by tensile testing of the dog bone-shaped specimens cut from the sheets. The results indicate that the elastic modulus of the porous PDMS is dependent on the pore size distribution of the structure. Moreover, the mechanical properties and pore microstructure are shown to be dependent on the solvent type used in the mixture.
{"title":"Investigation of Pore Size Distribution and Mechanical Properties of Porous Polydimethylsiloxane (PDMS) Structures Using Solvent Evaporation Technique","authors":"M. Abshirini, M. Altan, Yingtao Liu, M. Saha","doi":"10.1115/imece2021-70816","DOIUrl":"https://doi.org/10.1115/imece2021-70816","url":null,"abstract":"\u0000 This paper reports a fast and straightforward method for controlling the pore size distribution and mechanical properties of porous polydimethylsiloxane (PDMS) structures. The solvent evaporation-induced phase separation is implemented for the fabrication of absorbent PDMS sheets. The ternary polymer solution containing PDMS, water (nonsolvent), and three different solvents are prepared. Tetrahydrofuran, Heptane, and Toluene are the solvents explored in this study. The stepping heat treatment is applied to the sample to control the solvent evaporation and trigger the phase separation. The pore morphology and pore size distribution are explored using the scanning electron microscope images captured from the internal surface. The results demonstrate that the pore microstructure is sensitive to the solvent used in polymer solution preparation. Besides, the mechanical properties of the porous PDMS sheets are characterized by tensile testing of the dog bone-shaped specimens cut from the sheets. The results indicate that the elastic modulus of the porous PDMS is dependent on the pore size distribution of the structure. Moreover, the mechanical properties and pore microstructure are shown to be dependent on the solvent type used in the mixture.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75400154","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}
P. Capela, M. S. Souza, S. Costa, M. Fernandes, H. Figueiredo, R. Alves, I. Delgado, J. Teixeira, D. Soares
Most electronic failures that occur in equipment are due to stresses induced by differences in the Coefficient of Thermal Expansion (CTE) of the different materials in a Printed Circuit Board Assemblies (PCBA). During a thermal cycle, the incompatibility of CTE between the PCB and the components induces shear fatigue that may affect the reliability of the solder interconnections on the PCB, which can eventually lead to fracture and failure of the joints and the PCB. Due to the advancement in the electronic components industry, interest from the researcher’s point of view has grown in studying the influence of additives in the solder alloys, in relation to microstructure, physical and mechanical properties and, mainly in the CTE. In this work two types of additives (Bi and graphite powder) were tested in order to reduce the CTE of a lead-free solder (SAC305) solder paste for reflow soldering. Because the selected additives have different characteristics, namely different densities, a different method of SAC305 solder additivation was tested for each type of additive. For Bi addition in SAC305 alloy (up to 6.5 wt.%), after a mechanical mixing of it, with the solder paste, a fusion technique (with a thermal cycle similar to the used on the reflow soldering) was used. For composites with graphite (addition up to 0.1 wt.%) a double-printing method was used in order to achieve a homogeneous additive distribution, so that graphite remained in the final ingot. These additivated solder alloys were chemically analyzed and characterized for thermogravimetric properties. Samples microstructure were characterized by SEM/EDS analysis, and also they were tested for their electrical resistivity. With graphite addition there is a slight increase on the initial alloy melting temperature (∼1.5°C) and with Bi an almost linear decrease was obtained (∼16 °C for the higher tested Bi addition). Composites with bismuth have a decrease trend, with the additive increase content until close to 5%. The CTE value decreases almost linearly ((from 25 to ∼14.5 μm/(m·°C); R2 = 0.9905). However, the sample of SAC305 + 6.5% Bi does not follow this trend, which may indicate that for these and higher amounts of bismuth, the composite CTE stabilizes. For composites with graphite there is a reduction of CTE (from 25 to ∼17 μm/(m·°C) for 0.04 wt. % graphite addition). For higher graphite additions the CTE seems to increase. The obtained results show that both additives can be used in order to achieve a CTE target value close to the PCB copper PAD (17 μm/(m·°C). However, the mixing method used for graphite mixing on solder paste cannot be directly transposed to the reflow soldering technique.
{"title":"Solder Paste Additives for Thermal Expansion Control","authors":"P. Capela, M. S. Souza, S. Costa, M. Fernandes, H. Figueiredo, R. Alves, I. Delgado, J. Teixeira, D. Soares","doi":"10.1115/imece2021-72478","DOIUrl":"https://doi.org/10.1115/imece2021-72478","url":null,"abstract":"\u0000 Most electronic failures that occur in equipment are due to stresses induced by differences in the Coefficient of Thermal Expansion (CTE) of the different materials in a Printed Circuit Board Assemblies (PCBA). During a thermal cycle, the incompatibility of CTE between the PCB and the components induces shear fatigue that may affect the reliability of the solder interconnections on the PCB, which can eventually lead to fracture and failure of the joints and the PCB. Due to the advancement in the electronic components industry, interest from the researcher’s point of view has grown in studying the influence of additives in the solder alloys, in relation to microstructure, physical and mechanical properties and, mainly in the CTE.\u0000 In this work two types of additives (Bi and graphite powder) were tested in order to reduce the CTE of a lead-free solder (SAC305) solder paste for reflow soldering. Because the selected additives have different characteristics, namely different densities, a different method of SAC305 solder additivation was tested for each type of additive. For Bi addition in SAC305 alloy (up to 6.5 wt.%), after a mechanical mixing of it, with the solder paste, a fusion technique (with a thermal cycle similar to the used on the reflow soldering) was used. For composites with graphite (addition up to 0.1 wt.%) a double-printing method was used in order to achieve a homogeneous additive distribution, so that graphite remained in the final ingot.\u0000 These additivated solder alloys were chemically analyzed and characterized for thermogravimetric properties. Samples microstructure were characterized by SEM/EDS analysis, and also they were tested for their electrical resistivity.\u0000 With graphite addition there is a slight increase on the initial alloy melting temperature (∼1.5°C) and with Bi an almost linear decrease was obtained (∼16 °C for the higher tested Bi addition).\u0000 Composites with bismuth have a decrease trend, with the additive increase content until close to 5%. The CTE value decreases almost linearly ((from 25 to ∼14.5 μm/(m·°C); R2 = 0.9905). However, the sample of SAC305 + 6.5% Bi does not follow this trend, which may indicate that for these and higher amounts of bismuth, the composite CTE stabilizes. For composites with graphite there is a reduction of CTE (from 25 to ∼17 μm/(m·°C) for 0.04 wt. % graphite addition). For higher graphite additions the CTE seems to increase.\u0000 The obtained results show that both additives can be used in order to achieve a CTE target value close to the PCB copper PAD (17 μm/(m·°C). However, the mixing method used for graphite mixing on solder paste cannot be directly transposed to the reflow soldering technique.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84797685","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}
Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. Owing to the diverse physical and mechanical properties that can be tailored to suit a particular need, metal foams have become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. This paper presents an overview of all the traditional and the state of art manufacturing methods adopted till date with their advantages and limitations as well. The manuscript further investigates characterization techniques used to characterize metal foam. Also, a summary of the most relevant applications with actual examples is presented.
{"title":"Recent Developments in Processing and Characterization of Metal Foam: Review","authors":"Asima Zahoor, A. Mourad","doi":"10.1115/imece2021-73258","DOIUrl":"https://doi.org/10.1115/imece2021-73258","url":null,"abstract":"\u0000 Metal foam is a novel class of metals that is inspired by naturally occurring, functionally graded, cellular structures like wood and bones. Owing to the diverse physical and mechanical properties that can be tailored to suit a particular need, metal foams have become attractive to researchers and efforts are being made to optimize the methodology to develop the metal foam. This paper presents an overview of all the traditional and the state of art manufacturing methods adopted till date with their advantages and limitations as well. The manuscript further investigates characterization techniques used to characterize metal foam. Also, a summary of the most relevant applications with actual examples is presented.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84388154","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}
Benjamin Starr, Serge L. Shishkin, C. Sahay, Suhash Ghosh
Corrosion fatigue is the major damage mechanism responsible for the premature failure of the aircrafts and turbine parts, especially in the marine environment. It has been seen that even relatively mild corrosive atmospheres can reduce the fatigue strength of many structures considerably as compared to their fatigue strength in dry air. The process starts with the surface degradation due to the corrosion pits, that become fatigue initiation sites and the initial damage when the part is loaded. Microstructure and morphology of the surface pits is critical for the crack initiation. It is assumed that the cracks are initiated at the sharp corners and bottoms of the narrow “micropits”. The paper provides a statistical characterization of the crack initiation process based on these pits’ density and microstructure distribution. Based on the surface damage initiation analysis, new morphological characteristics combining the pit size and highest curvature are introduced and have shown to be the efficient metrics for pitting fatigue with the distribution of introduced morphological characteristics. The distribution of these characteristics is estimated from the measured data. Effects of pitting morphology are evaluated for various heat-treated Aluminum 2024 specimens, with varying distribution of pit shapes and curvatures. The statistical distribution of specimen life is estimated using the “weakest link” approach, that is, by computing the probability that at least one crack is initiated anywhere on the surface. The paper contains a detailed description of crack initiation’s statistical model, methodology of corrosion parameter estimation and representative numerical examples of statistical modeling. The surface pit characterization has been nondestructively measured on a Zygo ZeGage 3D profiler. The ZeGage uses a Coherence Scanning Interferometry (CSI) technique which uses the wavelength of light to define its high precision. A carefully calibrated CSI profiler can measure a larger range of surface qualities with repeatable results in sub-nanometer precision. High magnification (20x, 50x, 100x) lenses increase the versatility in measuring even smoother surfaces. Large area scanning was done using a segmentation approach. A large field of view of the selected lens and automated rapid scanning allowed for reasonably smaller data files obtained after stitching these individual segments.
{"title":"Probabilistic Study of Corrosion Pit-Induced Fatigue","authors":"Benjamin Starr, Serge L. Shishkin, C. Sahay, Suhash Ghosh","doi":"10.1115/imece2021-69336","DOIUrl":"https://doi.org/10.1115/imece2021-69336","url":null,"abstract":"\u0000 Corrosion fatigue is the major damage mechanism responsible for the premature failure of the aircrafts and turbine parts, especially in the marine environment. It has been seen that even relatively mild corrosive atmospheres can reduce the fatigue strength of many structures considerably as compared to their fatigue strength in dry air. The process starts with the surface degradation due to the corrosion pits, that become fatigue initiation sites and the initial damage when the part is loaded. Microstructure and morphology of the surface pits is critical for the crack initiation. It is assumed that the cracks are initiated at the sharp corners and bottoms of the narrow “micropits”. The paper provides a statistical characterization of the crack initiation process based on these pits’ density and microstructure distribution. Based on the surface damage initiation analysis, new morphological characteristics combining the pit size and highest curvature are introduced and have shown to be the efficient metrics for pitting fatigue with the distribution of introduced morphological characteristics. The distribution of these characteristics is estimated from the measured data. Effects of pitting morphology are evaluated for various heat-treated Aluminum 2024 specimens, with varying distribution of pit shapes and curvatures. The statistical distribution of specimen life is estimated using the “weakest link” approach, that is, by computing the probability that at least one crack is initiated anywhere on the surface. The paper contains a detailed description of crack initiation’s statistical model, methodology of corrosion parameter estimation and representative numerical examples of statistical modeling. The surface pit characterization has been nondestructively measured on a Zygo ZeGage 3D profiler. The ZeGage uses a Coherence Scanning Interferometry (CSI) technique which uses the wavelength of light to define its high precision. A carefully calibrated CSI profiler can measure a larger range of surface qualities with repeatable results in sub-nanometer precision. High magnification (20x, 50x, 100x) lenses increase the versatility in measuring even smoother surfaces. Large area scanning was done using a segmentation approach. A large field of view of the selected lens and automated rapid scanning allowed for reasonably smaller data files obtained after stitching these individual segments.","PeriodicalId":23837,"journal":{"name":"Volume 3: Advanced Materials: Design, Processing, Characterization, and Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76369208","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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