Mechanics of Tunable Hemispherical Electronic Eye Camera Systems That Combine Rigid Device Elements With Soft Elastomers

2013 ◽  
Vol 80 (6) ◽  
Author(s):  
Chaofeng Lü ◽  
Ming Li ◽  
Jianliang Xiao ◽  
Inhwa Jung ◽  
Jian Wu ◽  
...  
Keyword(s):  
Imaging System ◽  
Soft Materials ◽  
Heterogeneous Integration ◽  
Analytical Mechanics ◽  
Element Analysis ◽  
Camera Systems ◽  
Tunable Lenses ◽  
Analytical Expressions ◽  
Important Design ◽  
Electronic Eye

A tunable hemispherical imaging system with zoom capability was recently developed by exploiting heterogeneous integration of rigid silicon photodetectors on soft, elastomeric supports, in designs that can facilitate tunable curvature for both the lens and detector. This paper reports analytical mechanics models for the soft materials aspects of the tunable lenses and detector surfaces used in such devices. The results provide analytical expressions for the strain distributions, apex heights and detector positions, and have been validated by the experiments and finite element analysis. More broadly, they represent important design tools for advanced cameras that combine hard and soft materials into nonplanar layouts with adjustable geometries.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

Design of Microfabricated Mechanically Interlocking Metamaterials for Reworkable Heterogeneous Integration

2021 ◽  
Author(s):  
Geoffrey Garcia ◽  
Kody Wakumoto ◽  
Joseph Brown
Keyword(s):  
Analytical Models ◽  
Elastic Behavior ◽  
Heterogeneous Integration ◽  
Element Analysis ◽  
Microelectronic Devices ◽  
Mechanical Metamaterials ◽  
Dry Adhesives ◽  
Cantilever Array ◽  
Mechanical Bonding ◽  
Interconnect Technology

Abstract Next–generation interconnects utilizing mechanically interlocking structures enable permanent and reworkable joints between microelectronic devices. Mechanical metamaterials, specifically dry adhesives, are an active area of research which allows for the joining of objects without traditional fasteners or adhesives, and in the case of chip integration, without solder. This paper focuses on reworkable joints that enable chips to be removed from their substrates to support reusable device prototyping and packaging, creating the possibility for eventual pick-and-place mechanical bonding of chips with no additional bonding steps required. Analytical models are presented and are verified through Finite Element Analysis (FEA) assuming pure elastic behavior. Sliding contact conditions in FEA simplify consideration of several design variations but contribute ~10% uncertainty relative to experiment, analysis, and point-loaded FEA. Two designs are presented; arrays of flat cantilevers have a bond strength of 6.3 kPa, and non-flat cantilevers have a strength of 29 kPa. Interlocking designs present self-aligning in-plane forces that emerge from translational perturbation from perfect alignment. Stresses exceeding the material yield stress during adhesion operations present a greater concern for repeatable operation of compliant interlocking joints and will require further study quantifying and accommodating plastic deformation. Designs joining a rigid array with a complementary compliant cantilever array preserve the condition of reworkability for the surface presenting the rigid array. Eventual realization of interconnect technology based on this study will provide a great improvement of functionality and adaptability in heterogeneous integration and microdevice packaging.

scholarly journals Eliminating Underconstraint in Double Parallelogram Flexure Mechanisms

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Robert M. Panas ◽  
Jonathan B. Hopkins
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Measurement ◽  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Average Error ◽  
Static Stiffness ◽  
Element Analysis ◽  
Linkage Design ◽  
Analytical Expressions

We present an improved flexure linkage design for removing underconstraint in a double parallelogram (DP) linear flexural mechanism. This new linkage alleviates many of the problems associated with current linkage design solutions such as static and dynamic performance losses and increased footprint. The improvements of the new linkage design will enable wider adoption of underconstraint eliminating (UE) linkages, especially in the design of linear flexural bearings. Comparisons are provided between the new linkage design and existing UE designs over a range of features including footprint, dynamics, and kinematics. A nested linkage design is shown through finite element analysis (FEA) and experimental measurement to work as predicted in selectively eliminating the underconstrained degrees-of-freedom (DOF) in DP linear flexure bearings. The improved bearing shows an 11 × gain in the resonance frequency and 134× gain in static stiffness of the underconstrained DOF, as designed. Analytical expressions are presented for designers to calculate the linear performance of the nested UE linkage (average error < 5%). The concept presented in this paper is extended to an analogous double-nested rotary flexure design.

A Compact Cantilever Model That Includes Fillets

2012 ◽  
Author(s):  
Aarti Chigullapalli ◽  
Jason V. Clark
Keyword(s):  
Radius Of Curvature ◽  
Model Parameters ◽  
Beam Model ◽  
Stress Concentrations ◽  
Feature Size ◽  
Element Analysis ◽  
Size Limitation ◽  
Reducing Stress ◽  
Analytical Expressions ◽  
Typical Model

In this paper we present analytical expressions for determining the stiffness of cantilevers with fillets and tappers. We consider the unavoidable fillet due to the feature size limitation of lithography that rounds acute vertices, and the intentional tapper that is often used for reducing stress concentrations or can be used to reduce the effect of fillets. Previous compact models have not included the stiffness contributions from fillets. However, although fillets are small, they can measurably affect the performance of MEMS by affecting deflection or resonance frequency by their second most significant digit. We extend the well-known analytical beam model to include fillets. To our knowledge, this is the first analytical model of a filleted cantilever. In addition to the typical model parameters of beams, our model also includes process variation overcut and fillet radius of curvature, which are key parameters for MEMS designers. Our analytical solution is within 0.01% of finite element analysis.

Analytical Solution of Elastic-Plastic Buckling of a Square Steel Tube Column under Axial Compressive Load and Bending Moment

2010 ◽  
Vol 452-453 ◽  
pp. 485-488 ◽  
Author(s):  
Peng Niu ◽  
Gang Yang ◽  
Chun Fu Jin ◽  
Yi Xiong Wu
Keyword(s):  
Compressive Load ◽  
Bending Moment ◽  
Steel Tube ◽  
Plastic Buckling ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Axial Compressive Load ◽  
The Moment ◽  
Square Steel Tube ◽  
Analytical Expressions

Based on Ježek method of computing the elastic-plastic buckling of the member under the axial compressive load and the bending moment, the analytical expressions of calculating the ultimate load of buckling about the neutral axis with the moment of inertia for a square steel tube column are derived. By degenerated into the analytical expressions of the rectangular column and compared with the values of the finite element analysis (FEA) method, it shows that the analytical method in this paper is valid, which provides a new method of theoretical study for the elastic-plastic buckling of the member.

Error Estimation of DIC for Heterogeneous Strain States

2011 ◽  
Vol 70 ◽  
pp. 177-182 ◽  
Author(s):  
Yue Qi Wang ◽  
Pascal Lava ◽  
Dimitri Debruyne ◽  
Paul van Houtte
Keyword(s):  
Finite Element Analysis ◽  
Material Properties ◽  
Numerical Experiments ◽  
Transverse Direction ◽  
Imaging System ◽  
Rolling Direction ◽  
Image Correlation ◽  
Displacement Fields ◽  
Element Analysis ◽  
Speckle Patterns

Digital image correlation (DIC) involves certain errors during correlation, which are highly influenced by factors, e.g. image qualities, DIC parameters, and furthermore, degrees of deformation or strain states. In this contribution, attention is paid to the influence of strain states on the uncertainty of DIC, including the magnitude and the heterogeneity of the strains. A series of 2D-DIC numerical experiments are carried out on tensile specimens associated with finite element analysis (FEA). The specimens are made of 3 materials, i.e. steel DC06, steel DX54D+Z, and aluminium alloy Al6016, and cut into 3 different geometries, i.e. standard and 2 complex designs. Initial images were taken from these real specimens, which were all painted manually with random speckle patterns. Deformed images were obtained by imposing FE displacement fields on these undeformed initial images. Consequently, the errors source from imaging system are avoided, and only intrinsic errors of DIC itself are taken into account. The hardening behaviours of those materials in 3 different orientations were introduced to FEA for simulation, namely rolling direction (RD), transverse direction (TD) and 45o w.r.t. RD (45o). In FEA, homogeneous and heterogeneous strain states are achieved through applying uniaxial tension on two ends of the standard and complex specimens, respectively. The strain states are characterized by different material properties and geometries of specimens. DIC calculation are performed at various load steps to investigate the influence of the magnitude of the strain. Errors of the fields are compared among the different specimens to study the influence of the heterogeneity. In this contribution, the qualities of the speckle patterns are considered, since different patterns are applied to each experiment.

COMPRESSIVE FAILURE PREDICTION FROM NONLINEAR FINITE ELEMENT ANALYSIS OF A NOTCHED 0 DEGREE COMPOSITE SPECIMEN

2002 ◽  
Vol 02 (01) ◽  
pp. 135-149
Author(s):  
MELANIE G. VIOLETTE
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compressive Strength ◽  
Element Model ◽  
Design Criterion ◽  
Composite Specimen ◽  
Element Analysis ◽  
Buckling Instability ◽  
Experimental Values ◽  
Important Design

The strength of unidirectional composites is often lower in compression than in tension, making compressive strength an especially important design criterion. The compressive strength is sensitive to the presence of notches and stress gradients. Finite element analysis was used to determine the strain gradient at a shallow circular notch in one edge of a 0 degree carbon/epoxy composite specimen, and to predict failure due to a localized buckling instability. The specimen was first analyzed with a "global" model of the full specimen, and displacements along a curve near the notch were stored and used as boundary conditions for a more detailed "submodel" in the immediate vicinity of the notch. At the onset of instability, a displaced plot of the finite element model shows oscillations in the transverse direction along the arc of the notch, just off the centerline, which is essentially at the same location where failure initiated in the test specimens. Results are compared with experimental values for failure stress and notch strain concentration for a range of loading rates and test temperatures.

scholarly journals Mechanical and Compositional Implications of Gallium Ion Milling on Epoxy Resin

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2640
Author(s):  
Raz Samira ◽  
Atzmon Vakahi ◽  
Rami Eliasy ◽  
Dov Sherman ◽  
Noa Lachman
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Soft Materials ◽  
Morphological Data ◽  
Ion Milling ◽  
Element Analysis ◽  
Transmission Electron ◽  
Direct Measurements ◽  
Quantitative Results

Focused Ion Beam (FIB) is one of the most common methods for nanodevice fabrication. However, its implications on mechanical properties of polymers have only been speculated. In the current study, we demonstrated flexural bending of FIB-milled epoxy nanobeam, examined in situ under a transmission electron microscope (TEM). Controllable displacement was applied, while real-time TEM videos were gathered to produce morphological data. EDS and EELS were used to characterize the compositions of the resultant structure, and a computational model was used, together with the quantitative results of the in situ bending, to mechanically characterize the effect of Ga+ ions irradiation. The damaged layer was measured at 30 nm, with high content of gallium (40%). Examination of the fracture revealed crack propagation within the elastic region and rapid crack growth up to fracture, attesting to enhanced brittleness. Importantly, the nanoscale epoxy exhibited a robust increase in flexural strength, associated with chemical tempering and ion-induced peening effects, stiffening the outer surface. Young’s modulus of the stiffened layer was calculated via the finite element analysis (FEA) simulation, according to the measurement of 30 nm thickness in the STEM and resulted in a modulus range of 30–100 GPa. The current findings, now established in direct measurements, pave the way to improved applications of polymers in nanoscale devices to include soft materials, such as polymer-based composites and biological samples.

Mechanics of Regular-Shape Nanomeshes for Transparent and Stretchable Devices

2020 ◽  
Vol 87 (10) ◽  
Author(s):  
Sandra Vinnikova ◽  
Hui Fang ◽  
Shuodao Wang
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Analytical Models ◽  
Regular Polygons ◽  
Element Analysis ◽  
Micro Scale ◽  
Regular Shape ◽  
The Finite Element Analysis ◽  
Mechanical Performances ◽  
Analytical Expressions

Abstract Open nanomesh structures with nano/micro-scale geometric dimensions are important candidates for transparent, soft, and stretchable microelectrodes. This study developed analytical and numerical mechanics models for three types of nanomeshes that consist of regular polygons and straight traces. The analytical models described the transparency, effective stiffness, and stretchability of the nanomeshes and agree with the finite element analysis. The mechanical performances of the nanomeshes are compared based on the same level of transparency. The validated analytical expressions provide convenient guidelines for designing the nanomeshes to have levels of transparency and mechanical properties suitable for bio-integrated applications.

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