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Unique Wrinkling Behavior Of Stiff Thin Films On Shape Memory Polymers, Jianliang Xiao
Unique Wrinkling Behavior Of Stiff Thin Films On Shape Memory Polymers, Jianliang Xiao
Society of Engineering Science 51st Annual Technical Meeting
Shape memory polymers (SMPs) can remember two or more distinct shapes, and therefore can have many applications. We here presents combined experimental and theoretical studies on the wrinkling of stiff thin films on SMPs. Experimental results show well-defined, wavy profiles of the thin films. Time and temperature dependent wrinkle formation and evolution were observed. It was shown that both wrinkling wavelength and amplitude increase with SMP relaxation. This is different from earlier observations of thin film wrinkling on soft substrates, which show decreasing wavelength and increasing amplitude when compression increases. Finite element simulations accounting for the thermomechanical behavior of SMPs …
Technology And Applications Of Microassembly Using Elastomer Stamps, Matthew Meitl
Technology And Applications Of Microassembly Using Elastomer Stamps, Matthew Meitl
Society of Engineering Science 51st Annual Technical Meeting
The microelectronics industry benefits from reduced costs and improved performance afforded by miniaturization of components. Advanced lithographic methods provide the greatest levels of miniaturization in a high-throughput (parallel), high-precision (deterministic) manner, but the same methods are limited in their ability to integrate multiple, diverse heterogeneous materials in a miniaturized system. In contrast, joining diverse materials together into a system typically happens in packaging, using assembly techniques that usually involve serial operations and impose constraints on the sizes and shapes of the components to be assembled. As a result, the benefits of miniaturization are not fully accessible to systems that require …
Keynote – Mechanics Of Cellular Uptake Of One- And Two-Dimensional Nanomaterials, Huajian Gao
Keynote – Mechanics Of Cellular Uptake Of One- And Two-Dimensional Nanomaterials, Huajian Gao
Society of Engineering Science 51st Annual Technical Meeting
With the rapid development of nanotechnology, various types of nanoparticles, nanowires, nanofibers, nanotubes, and atomically thin plates and sheets have emerged as candidates for an ever increasing list of potential applications for next generation electronics, microchips, composites, barrier coatings, biosensors, drug delivery, and energy harvesting, and conversion systems. There is now an urgent societal need to understand both beneficial and hazardous effects of nanotechnology which is projected to produce and release thousands of tons of nanomaterials into the environment in the coming decades. This discussion aims to present an overview of some recent studies conducted at Brown University on the …
Compliant, Heterogeneously Integrated Micro-Vcsels, Jongseung Yoon
Compliant, Heterogeneously Integrated Micro-Vcsels, Jongseung Yoon
Society of Engineering Science 51st Annual Technical Meeting
Vertical cavity surface emitting lasers (VCSELs) represent a ubiquitous light source with unique performance characteristics that excel edge-emitting lasers or light-emitting diodes. VCSELs are available, however, mostly on growth wafers in rigid, planar formats over restricted areas, thereby frustrating their use for applications that benefit greatly from unconventional design options including large-scale, programmable assemblies on unusual substrates, hybrid integration with dissimilar materials and devices, or mechanically compliant constructions. Here the author will present our recent efforts on materials design and fabrication strategies that overcome limitations of conventional VCSELs and create new application opportunities that are unavailable in existing technologies. Specialized …
Thermal Analysis Of The Operation Of Microscale Inorganic Light Emitting Diodes, Jizhou Song
Thermal Analysis Of The Operation Of Microscale Inorganic Light Emitting Diodes, Jizhou Song
Society of Engineering Science 51st Annual Technical Meeting
An analytical model is developed to study the thermal properties of microscale inorganic light emitting diodes (μ-ILEDs) with ultra-thin geometries and layouts. The predicted surface and μ-ILED temperatures agree well with experiments and finite element simulations. A simple scaling law is obtained for the normalized μ-ILED temperature versus the normalized μ-ILED size. This study provides theory to guide the design of layouts that minimize adverse thermal effects not only on the performance of μ-ILEDs for solid state lighting, but also for applications integrating μ-ILED devices on complex/soft substrate as are currently of interest in optogenetics and other emerging areas in …
Keynote: Experiments And Viscoelastic Analysis Of Peel Test With Patterned Strips For Applications To Transfer Printing, Yonggang Huang
Keynote: Experiments And Viscoelastic Analysis Of Peel Test With Patterned Strips For Applications To Transfer Printing, Yonggang Huang
Society of Engineering Science 51st Annual Technical Meeting
Transfer printing is an exceptionally sophisticated approach to assembly and micro/nanofabrication that relies on a soft, elastomeric “stamp” to transfer solid, micro/nanoscale materials or device components from one substrate to another, in a large-scale, parallel fashion. The most critical control parameter in transfer printing is the strength of adhesion between the stamp and materials/devices. Conventional peel tests provide effective and robust means for determining the interfacial adhesion strength, or equivalently, the energy release rate, and its dependence on peel speed. The results presented here provide analytic solutions for tests of this type, performed using viscoelastic strips with and without patterns …
Micro-Masonry (For Multismall Volume Rapid Fabrication), Seok Kim
Micro-Masonry (For Multismall Volume Rapid Fabrication), Seok Kim
Society of Engineering Science 51st Annual Technical Meeting
The speaker presents a new micromanufacturing route, termed “micro-masonry” for multismall volume rapid fabrication of MEMS structures and devices. This approach involves a transfer printing-based assembly of micro/nanoscale materials, optionally, in conjunction with material bonding techniques relying on rapid thermal annealing. The discussion starts with the current state-of-the-art of transfer printing via advanced polymer stamps which exhibit exceptional reversible dry adhesion. Subsequently, the procedures of the preparation, assembly, and bonding of three major materials in MEMS such as silicon, silicon dioxide, and gold are introduced. Finally, several system level applications including imbricate photonic scales, vertical hidden comb drives, MEMS scanners, …
Large Area Printed Three-Dimensional Optical Metamaterials, Debashis Chanda
Large Area Printed Three-Dimensional Optical Metamaterials, Debashis Chanda
Society of Engineering Science 51st Annual Technical Meeting
Metamaterials are engineered materials where artificial properties like negative refractive index, zero-index, -artificial magnetism, perfect absorption, and others have been demonstrated. Various two-dimensional metamaterials were fabricated using conventional lithographic techniques. In order to qualify metamaterials as true -materials that enables curving out real devices, one need to develop three-dimensional metamaterials. However, fabrication of three-dimensional metamaterials based on conventional electron and ion beam lithography is very tedious. Although this method provides the necessary submicron resolution and excellent control over the in-plane geometries, its practical use is restricted to overall lateral dimensions of <100s of microns. This size limitation, taken together with the complexity of the lithography tools and their extremely slow patterning speeds, makes this technique poorly suited to requirements for realistic applications in superlenses, photonic components or others, where cost, throughput, area coverage, and long range uniformity are important considerations. Alternative -approaches to 3D nanofabrication, such as those based on colloidal self-assembly, interference lithography, and two photon polymerization based direct laser writing lack the ability to embed multiple metal/dielectric layers over a 3D space. Nanoimprint lithography and various forms of soft lithography, in their standard embodiments, offer the necessary resolution, but they do not form 3D structures easily. We developed a nanotransfer printing method that is directly applicable to fabrication of 3D metamaterials with excellent optical characteristics, in ways that are scalable to arbitrarily large areas and compatible with manufacturing. We use the resulting methods to fabricate 3D near-infrared negative index metamaterials with 11-layers and sub-micron unit cell dimensions, over areas > 75 cm2, corresponding to >105 x 105 unit cells, …
Stretchable Bioelectronics For Medical Devices And Systems, Roozbeh Ghaffari
Stretchable Bioelectronics For Medical Devices And Systems, Roozbeh Ghaffari
Society of Engineering Science 51st Annual Technical Meeting
Advances in the microelectronics and telecommunications industries have driven important breakthroughs in medical technologies and health diagnostics over the past decade. However, there are fundamental gaps in size, sensing modalities and mechanical properties between the standard rigid electronics, employed in medical devices today, and the signals emitted by soft biological structures. Here, the author describes novel materials, mechanics, and designs for emerging classes of health monitoring systems and invasive medical devices, including soft wearable patches and flexible catheter-based systems. These emerging devices incorporate microfabricated arrays of sensors (e.g., dry electrodes, temperature sensors, and accelerometers), actuators (e.g., micro-LEDs, piezo-electric ribbons, pacing …
High Density Semiconducting Nanotube Arrays For High-Performance Electronics, Qing Cao
High Density Semiconducting Nanotube Arrays For High-Performance Electronics, Qing Cao
Society of Engineering Science 51st Annual Technical Meeting
Single-walled carbon nanotubes are poised to replace silicon in high-performance microprocessor chips and are expected to offer a significant improvement in energy-delay product. However, one key challenge of realizing such a technology is to produce semiconducting nanotube arrays with both minuscule and uniform inter-tube pitch to provide sufficient packing density, power output, and performance homogeneity for each transistor. Here, we will review our latest progress on assembling pre-sorted high purity semiconducting nanotubes into densely packed arrays. In an example, double-layered arrays with full surface coverage and a tube density >500 tubes/μm are assembled with Langmuir–Schaefer method. The nanotube pitch is …
Keynote – Nanomembrane Materials And Soft Fabrication Methods In Sustainable Energy Technologies, Ralph Nuzzo
Keynote – Nanomembrane Materials And Soft Fabrication Methods In Sustainable Energy Technologies, Ralph Nuzzo
Society of Engineering Science 51st Annual Technical Meeting
The fabrication of high performance integrated circuits provides examples of the most sophisticated manufacturing methods, as well as the most high performance materials, used in any area of modern technology. The advanced functional systems they provide are ones that are generally characterized by a massive integration of circuit elements within compact, rigid, and essentially planar form factor devices. New means of fabrication and enabling nanomembrane materials are providing means through which it is possible to lift these constraints – doing so in ways that both provide capacities for high performance while enabling new opportunities in technology. Examples include: light weight, …
Discovery Enabled By In-Situ Synchrotron X-Ray Techniques, Yugang Sun
Discovery Enabled By In-Situ Synchrotron X-Ray Techniques, Yugang Sun
Society of Engineering Science 51st Annual Technical Meeting
Understanding the complex mechanism of nanocrystal formation and transformation in solutions represents a challenge in materials science. For example, formation of colloidal noble metal nanocrystals from homogeneous liquid solutions involves many complicated processes that are poorly understood. The absence of enough knowledge of nanoparticle formation in liquid media is due to the difficulty in developing effective tools to “see through” solvents and probe chemical and physical events in the liquids. This situation also leads to challenging barriers that prevent the synthesis of functional nanoparticles with precisely tailored properties and better understanding of the dependence of nanoparticles’ performance on their physical …
Modeling Of Cortical Bone Adaptation Due To Oscillatory Loading, Iwona Jasiuk
Modeling Of Cortical Bone Adaptation Due To Oscillatory Loading, Iwona Jasiuk
Society of Engineering Science 51st Annual Technical Meeting
Bone is a living tissue which constantly undergoes a complex process of adaptation in response to its biochemical and mechanical environment to optimize its resistance to failure. The bone adaptation due to the mechanical loading is dependent on a combination of different mechanical stimuli such as the magnitude and frequency of the applied load, number of cycles, number of bouts, time between bounds, and other factors. In this presentation we discuss the model of adaptation in cortical bone which employs the finite element stress analysis coupled with an evolution law. The finite element model is generated from microcomputed tomography images …
Gravity Driven Hydraulic Fracture With Finite Breadth, Dmitry Garagash, Leonid Germanovich
Gravity Driven Hydraulic Fracture With Finite Breadth, Dmitry Garagash, Leonid Germanovich
Society of Engineering Science 51st Annual Technical Meeting
This study outlines a new method for disposing of hazardous (e.g., nuclear) waste. The technique is called Abyssal Sequestration, and it involves placing the waste at extreme depths in Earth’s crust where it could achieve the geologically long period of isolation. Abyssal Sequestration involves storing the waste in hydraulic fractures driven by gravity, a process we term as gravity fracturing. In short, we suggest creating a dense fluid (slurry) containing waste, introducing the fluid into a fracture, and extending the fracture downward until it becomes long enough to propagate independently. The fracture will continue to propagate downward to great depth, …
Grainsize Effect On The Crushing Behavior Of Unsaturated Granular Solids, Giuseppe Buscarnera
Grainsize Effect On The Crushing Behavior Of Unsaturated Granular Solids, Giuseppe Buscarnera
Society of Engineering Science 51st Annual Technical Meeting
Failure and strain-localization in granular soils and porous rocks subjected to high pressures involves considerable alteration of the microstructure. Such processes are affected by the grainsize characteristics (e.g., grain size distribution and mean grain size), as well as by environmental variables such as moisture content and capillary pressure. In this contribution, we use a reformulation of the Breakage Mechanics theory to model comminution in wet granular assemblies. By using an extensive dataset for sands, we quantify the relation between a geometric descriptor of the assembly (i.e., the mean grainsize) and the constants that control the suction air-entry value and the …
Liquefaction In Granular Matter As A Diffuse Instability With Micromechanical Origin, Jose Andrade
Liquefaction In Granular Matter As A Diffuse Instability With Micromechanical Origin, Jose Andrade
Society of Engineering Science 51st Annual Technical Meeting
In this contribution, we will show that liquefaction can be treated as a diffuse instability, within the framework of bifurcation theory. Furthermore, for the first time, we will show that liquefaction instability has a micromechanical origin and explicitly show the necessary conditions to attain liquefaction from a micromechanical point of view. All of these findings are contrasted and shown to support all phenomenological observations corresponding to dense and loose sands.
Fractals At Elastic–Plastic Transitions In Metals, Soils, And Rocks, Martin Ostoja-Starzewski
Fractals At Elastic–Plastic Transitions In Metals, Soils, And Rocks, Martin Ostoja-Starzewski
Society of Engineering Science 51st Annual Technical Meeting
A range of studies indicate that a fractal growth of plastic domains is characteristic of elastic–plastic transitions in metallic, soil-like, and rock-like materials where elastic moduli and/or coefficients of friction, cohesion, and dilatation [1-5]. More specifically, all these material parameters are taken as nonfractal random fields in 2D or 3D, with weak noise-to-signal ratios, in a statistical continuum models. Statistical analysis is used to assess the anisotropy of those shear bands. All the macroscopic responses display smooth transitions but, as the randomness vanishes, they turn into a sharp response of an idealized homogeneous material. Notably, increasing hardening modulus and friction …
Predicting Strain Localization In High Porosity Materials, Kathleen Issen, Mathew Ingraham
Predicting Strain Localization In High Porosity Materials, Kathleen Issen, Mathew Ingraham
Society of Engineering Science 51st Annual Technical Meeting
Rudnicki and Rice (1975; RR75) proposed that strain localization in pressure-dependent materials could be -modeled as a bifurcation from homogeneous deformation, because of a constitutive instability in an initially uniform material undergoing inelastic deformation. Using a continuum approach, details of the material mesostructure were not specified, but rather enter through the choice of continuum constitutive relation. Although RR75 had dilatant, low porosity rocks in mind, they used a sufficiently general constitutive relation (inelastic deformation depends on first and second invariants of stress) to enable the localization framework to be applied to a variety of materials. Of relevance, here is the …
Modeling Fracture In Nanotwinned Matetrials, Huajian Gao
Modeling Fracture In Nanotwinned Matetrials, Huajian Gao
Society of Engineering Science 51st Annual Technical Meeting
The author reports on the results obtained so far through a combination of advanced experimental and statistical techniques as well as constitutive modeling based on a continuum dislocation dynamics and viscoplastic model. The implementation relies on a finite element code to perform simulations of DP980 steels which can be compared to experiments. Design guidelines will be in the form of a microstructure map that relates thermo-mechanical processing conditions to desired properties and cost constraints. The aim will be to guide manufacturers in selecting a series of processing steps to transform the original material to a final material with specific properties.
Keynote: Going From Cold To Hot With John Rudnicki, James Rice
Keynote: Going From Cold To Hot With John Rudnicki, James Rice
Society of Engineering Science 51st Annual Technical Meeting
In his earliest scientific work, John W. Rudnicki began studies on shear localization, which helped clarify widely observed process in rock and soil mechanics (and metals and polymers too) and which he ultimately generalized to a novel and highly informative approach to understanding compaction bands in porous rocks. His early studies did consider possible interactions of the deforming solid, when porous, with infiltrating pore fluids, but they made no particular reference to the effects of temperature changes during deformation. That changed most significantly in a pair of recent articles (slated for publication in J. Geophys. Res. – Solid Earth in …
Modeling Deformation Bands In Thermal Softening And Fluid Infiltrating Porous Solids At Finite Strain, Waiching Sun, Claudio Tamagnini
Modeling Deformation Bands In Thermal Softening And Fluid Infiltrating Porous Solids At Finite Strain, Waiching Sun, Claudio Tamagnini
Society of Engineering Science 51st Annual Technical Meeting
Onset and modes of deformation bands are often influenced by nonmechanical loading triggered by seepage of pore fluid and thermal effects. Experimental evidence has established that temperature changes can alter the shape and size of the yield surface and cause shear band to form in geomaterials that are otherwise stable. Understanding this thermo-hydro-mechanical responses are important for many engineering applications, such as carbon dioxide storage and extraction of hydrocarbon in which hot or cool fluid are often injected into deep porous rock formations. The purpose of this research is to simulate this coupled process using a thermoporoplasticity model with extended …
Importance Of The Intermediate Principal Stress On Failure And Localization Behavior In High Porosity Rocks, Mathew Ingraham
Importance Of The Intermediate Principal Stress On Failure And Localization Behavior In High Porosity Rocks, Mathew Ingraham
Society of Engineering Science 51st Annual Technical Meeting
The localization criterion developed by Rudnicki and Rice(1975), whereas intended for low porosity rocks has been found to be applicable to many other types of materials, including high porosity rocks such as sandstone. The localization criterion shows that regardless of the constitutive model, intermediate principal stress dependence arises as a result of the localization framework. This means, that to investigate localization, under anything but the simplest conditions, true triaxial tests are required. A series of true triaxial tests was performed to investigate the localization criterion and the effect of the intermediate principal stress. Tests were run at Sandia National Laboratories …
True Triaxial Failure Characteristics In Rocks From Granite To Sandstone: Experimental Results And Theoretical Predictions – A Review, Bezalel Haimson
True Triaxial Failure Characteristics In Rocks From Granite To Sandstone: Experimental Results And Theoretical Predictions – A Review, Bezalel Haimson
Society of Engineering Science 51st Annual Technical Meeting
Mogi’s (1971) seminal article on a new testing machine for conducting true triaxial experiments in rock included the first set of test results showing that failure (in the form of s1, peak) is a function of not only s3, but also of s2. However, Mogi’s pioneering work went seemingly unnoticed by the rock mechanics community. Some 30 years later, Haimson and colleagues (2000–2014) fabricated a similar loading system and employed it to determine true triaxial deformability and failure criteria in several crystalline and clastic rocks. The most important discovery enabled by true triaxial measurements was the effect of the intermediate …
Comminution Of Solids Due To Kinetic Energy Of High-Rate Shearing: Impact, Shock, And Shale Fracturing, Zdenek P Bazant, Yewang Su, Marco Salviato, Ferhun Caner
Comminution Of Solids Due To Kinetic Energy Of High-Rate Shearing: Impact, Shock, And Shale Fracturing, Zdenek P Bazant, Yewang Su, Marco Salviato, Ferhun Caner
Society of Engineering Science 51st Annual Technical Meeting
Keynote: Fragmentation, crushing, and pulverization of solids, briefly called comminution, has long been a problem of interest for mining, tunneling, explosions, meteorite impact, missile impact and penetration, groundshock, defence against terrorist attack, and various kinds of industrial processes. Particularly intriguing is the idea that shock waves generated in the borehole by electrohydraulic pulsed arc could comminute gas shale so as to achieve a sufficient increase of permeability, which might allow reducing the discharge of contaminated water needed for hydraulic fracturing. Although many semi-empirical models for impact analysis abound in the literature, and whereas the fragmentation in the so-called “Mescall” zones …
Progressive Failure Along Frictional Discontinuities, Antonio Bobet
Progressive Failure Along Frictional Discontinuities, Antonio Bobet
Society of Engineering Science 51st Annual Technical Meeting
The most important mechanism for deformation and failure in rock masses under relatively low stresses is slip along pre-existing discontinuities. These discontinuities can be viewed as fractures and their behavior can be approximated using Linear Elastic Fracture Mechanics theory. Slip along a frictional discontinuity can be approached as initiation and propagation of a mode II fracture along its own plane. Fracture mechanics theories predict that under pure mode II loading initiation will occur when the energy release rate of the fracture attains a critical value (GIIC), which is generally taken as a material property. The research conducted shows that this …
Some Observations And Analyses Of The 2011 Tohoku Earthquake And Tsunami, Kt Chau
Some Observations And Analyses Of The 2011 Tohoku Earthquake And Tsunami, Kt Chau
Society of Engineering Science 51st Annual Technical Meeting
First, this article summarizes our field observations made along the coastlines of Miyagi and Iwate Prefectures in the Tohoku areas in 2012, including the cities of Ishinomaki, Onagawa, Minamisanriku, Kesennuma, Rikuzentakata, Ofunato, and Kamaishi. Some peculiar observations are reported, including the overturned buildings at Onagawa. Secondly, tsunami simulations were performed using COMCOT based on linear shallow water equations. The resolution of the bathymetry used is based on 1 min or 1.36 km grid downloadable from NOAA website. Three focal mechanism models proposed by United States Geological Survey (USGS), Chinese Academy of Science (CAS), and Tsukuba University (TU) were used to …
Prediction Of Viscoelastic And Plastic Properties Of Polymers Using Indentation, Vineet Agarwal
Prediction Of Viscoelastic And Plastic Properties Of Polymers Using Indentation, Vineet Agarwal
Society of Engineering Science 51st Annual Technical Meeting
Indentation methodologies are gaining popularity as they provide means of local property estimation, utilize smaller sample sizes, and do not destroy specimens. Classically, indentation has been used to measure hardness and Young’s modulus [1], but researchers have also proposed ways of predicting stress–strain curves [2], yield strength [3], and fracture toughness [3]. Different indentation techniques are being used by researchers for different types of investigations. Nanoindentation is an indentation at very small scales to obtain local properties via single indent. Reference Point Indentation (RPI) is a technique wherein multiple indents are carried out at the same location and the material …
Implementation Of Nanoscience And Nanoengineering Into Undergraduate Mechanical Engineering Design Courses, Xiangfa Wu
Implementation Of Nanoscience And Nanoengineering Into Undergraduate Mechanical Engineering Design Courses, Xiangfa Wu
Society of Engineering Science 51st Annual Technical Meeting
Recent development in nanoscience and nanotechnology has substantially shaped today’s engineering activities and human’s life and will significantly impact the entire society in various ways in the near future. Today’s undergraduate engineering education needs to represent such a trend to nurture the next generation of labor forces with well-prepared knowledge and skills. This study is to introduce our recent efforts to implement hands-on group design projects on nanofabrication machines for scale-up production of nanofibers and nanowires into existing mechanical engineering design courses to improve undergraduate students’ nanoscale science and engineering education. The background of nanotechnology and scalable nanofabrication methods were …
The Effect Of Grain Size Distributions On Low-Temperature Creep In A Thin Film, Peter Kolis
The Effect Of Grain Size Distributions On Low-Temperature Creep In A Thin Film, Peter Kolis
Society of Engineering Science 51st Annual Technical Meeting
Thin films with microcrystalline and nanocrystalline grains are used in MEMS and thin films for electronics. These systems have mechanical properties that depend on the microstructure. Grain size is frequently reported only as mean values or bounds. It has been demonstrated, however, that a mean grain size value is insufficient to describe the microstructure of these materials and the resulting macroscopic mechanical properties. For example, deformation mechanisms at this scale demonstrate sensitivity to grain size, and variations in yield stress, hardness, ductility, and plastic behavior have all been attributed to the varying distributions of grain size in samples with identical …
Kinematics-Based Tracking Of Cells And Fluorescent Beads Using Feature Vectors, Roger Rowe, Elliot Elson, Guy Genin
Kinematics-Based Tracking Of Cells And Fluorescent Beads Using Feature Vectors, Roger Rowe, Elliot Elson, Guy Genin
Society of Engineering Science 51st Annual Technical Meeting
Tracking of cells or fluorescent beads from images of deforming or developing biological systems is a central challenge in biomechanics. In the former case, the objective is often to find the same cell in a tissue or on a Petri dish that has been imaged before and after time in an incubator. In the latter case, the objective is often to estimate mechanical tractions based upon displacement of fluorescent beads embedded in a defined extracellular matrix. A great number of techniques exist for this purpose, and all face challenges in matching cells and beads from one image to the next …