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Behavior and Mechanics of Multifunctional and Composite Materials 2007
Abstract
The papers included in this volume were part of the technical conference cited on the cover and title page. Papers were selected and subject to review by the editors and conference program committee. Some conference presentations may not be available for publication. The papers published in these proceedings reflect the work and thoughts of the authors and are published herein as submitted. The publisher is not responsible for the validity of the information or for any outcomes resulting from reliance thereon.
... The first model in the LTE class has been developed by Liu, Gall, Dunn, and Greenberg (2005) for the uniaxial deformation state and subsequently extended by the same authors to general three-dimensional problems (Liu, Gall, Dunn, Greenberg, & Diani, 2006). In the following years, the original Liu et al. model has been extensively discussed in the literature with numerous modifications and extensions (Chen & Lagoudas, 2008;Gilormini & Diani, 2012;Husson, Dubois, & Sauvat, 2011;Jarali, Raja, & Upadhya, 2010;Li, 2008;Mather et al., 2009;Ryan, Quinlan, & Bruzzi, 2010;Sinha, Jarali, & Raja, 2011;Siskind, 2008;Siskind & Smith, 2008). Interesting enough, the analysis of that literature shows that many of these presumably improved models, when tested against the Liu et al. (2005Liu et al. ( , 2006 data, show a less accurate prediction than the original model. ...
... A detailed discussion of various constitutive theories belonging to the class of linear thermoelastic (LTE) models is given in Gilormini and Diani (2012) and further details may be found in the original papers (Chen & Lagoudas, 2008;Husson et al., 2011;Jarali et al., 2010;Li, 2008;Liu et al., 2005Liu et al., , 2006Mather et al., 2009;Ryan et al., 2010;Sinha et al., 2011;Siskind, 2008;Siskind & Smith, 2008;Volk, 2009). Here we present the mathematical generalization of all these models. ...
... The obtained with this slight modifications solutions give somewhat better coincidence of the results with data for the stress storage but less accurate for the stress recovery (Fig. 6). Still another attempt to improve the Liu et al. model has been presented in Siskind (2008) and Siskind and Smith (2008). However, two versions of their model tested against the Liu et al. data give rather poor predictions of the stress recovery profiles (Fig. 6). ...
Mechanical instability and large deformation are pervasive occurrences on stressed soft material surface patterns, which are normally detrimental to device performance. In this dissertation we show that these phenomena can be harnessed on structured polymeric thin films for surface patterning, strong dry adhesion and guided wettability. On dyed SU-8 photoresist films with graded depth-wise crosslinking density, we study the swelling-induced wrinkling. We demonstrate that isotropic surface wrinkles can be aligned with low aspect ratio 1-D channel-type pre-patterns. By varying the pitch and height ratios, defined as the pre-pattern pitch and height of the channels to the wrinkle wavelength and amplitude, respectively, we construct a morphological diagram of the confined wrinkles. For pitch ratios much larger than 1, the wrinkle morphology is predominantly isotropic. As pitch ratio decreases to ~ 1, the wrinkles arrange to out-of-phase 1-D bumps along the mountain regions of the channels. For pitch ratio much smaller than 1, the wrinkles evolve from in-phase perpendicular (to the channels) wrinkles, coexisting perpendicular wrinkles and localized patterns back to isotropic wrinkles in the order of decreasing height ratios.
In a separate material system, we utilize the buckling of high aspect ratio shape memory polymer (SMP) pillars to develop a strong interlocking dry adhesive. We engage the two identical pillar arrays together above the glass transition temperature of SMP (80 °C), where the SMP modulus drops by 3 orders of magnitude, leading to mutual buckling and deformation of the pillars when interlocked. Our finite element analysis and comparison of the calculated adhesion versus experimental data suggest that the adhesion force originates primarily from the pillar interweaving and secondarily from pillar indentation. The resultant pillar-to-pillar adhesion forces in normal (~ 54 N/cm2) and shear (~ 72 N/cm2) direction are found much larger than the pillar-to-flat (~ 12 N/cm2 in normal and ~ 15 N/cm2 in shear) and flat-to-flat contacts (~ 7 N/cm2 in normal and ~ 16 N/cm2 in shear). We further tune the adhesion anisotropy, designated by the ratio of shear to normal adhesion, by changing the pillar spacing. In spite of the strong adhesion, we show that the engaged adhesive can be easily separate on demand by heating to 80 °C.
Using similar SMP pillars, we design a reconfigurable surface to control surface wettability. Specifically, we report that the water droplets convert from low adhesion Cassie state on the original (or recovered) straight pillars to fully pinned Wenzel state on deformed pillars. Potentially, surface with both straight and deformed pillars can be utilized as a reprogrammable water collecting surface. Employing the deformed pillars, we present an advanced patterning method based on the deformed SMP pillars to transfer nanoparticle assemblies from donor substrates onto selected locations of pillars. Finally, we show a new approach to precisely control the tilting angle of the SMP pillars by coating the deformed pillars with a layer of metal, which hinders the full recovery of SMP pillars. On the composite surface, we observe strong anisotropic liquid spreading behavior, where the liquid propagates predominantly in the opposite direction of the pillar tilting.
Conducting polymers have received increasing attention in both fundamental research and various fields of application in recent decades, ranging in use from biomaterials to renewable energy storage devices. Processing of conducting polymers into fibrillar structures through spinning has provided some unique capabilities to their final applications. Compared with non fibrillar forms, conducting polymer fibres are expected to display improved properties arising mainly from their low dimensions, well-oriented polymer chains, light weight and large surface area to volume ratio. Spinning methods have been employed effectively to produce technological conducting fibres from nanoscale to hundreds of micrometre sizes with controlled properties. This review considers the history, categories, the latest research and development, pristine and composite conducting polymer fibres and current/future applications of them while focus on spinning methods related to conducting polymer fibres.
Traditional 1-D and 2-D composite materials have excellent in-plane properties. However, they are susceptible to interlaminar crack and crack growth leading to delaminations and catastrophic failure of the composite structures. To remedy these problems, researchers have developed 3-D composites using through-the-thickness stitching and/or braiding. However, these two techniques have their own problems. For braiding, the part thickness should be known a priori, which is not practical. Besides the fiber architecture is not arranged orthogonally. For the stitching, it has been shown that while through-the-thickness properties increase, in-plane properties decrease. Here, we explain a novel technique, developed by the authors and co-workers, to develop 3-D multifunctional hierarchical nanocomposites with superior properties. In this approach, multi-walled carbon nanotubes (MWCNTs) are grown vertically over 2-D microfiber woven fabric cloth, without altering the 2-D cloth architecture, to create nano-forests coating of MWCNTs in the thickness direction to yield 3-D orthogonal fiber architechture. The 3-D nano-forest woven cloths are later impregnated with the resins and are subsequently stacked, vacuum bagged, and cured to give 3-D multifunctional hierarchical nanocomposites. Since MWCNTs have superior mechanical, thermal, and electrical properties, the hierarchically developed 3-D multifunctional nanocomposites have enhanced mechanical, thermal, thermomechanical, damping, and electrical properties by many folds.
This paper is concerned about the synthesis of shape memory styrene copolymer and the investigation of the influence of cross-linking degree on its shape memory effect. As one of novel actuators in smart materials, shape memory polymers (SMPs) have been investigated intensively. Styrene copolymer with proper cross-linking degree can exhibit shape memory effect (SME). In this paper, the influence of cross-linking degree on shape memory effect of styrene copolymer was investigated through altering the dosage of cross-linking agent. The cross-linking degree of styrene copolymer was determined by measuring the gel content. The glass transition temperature (Tg) of styrene copolymer, which is determined the cross-linking degree, was measured by Dynamic Mechanical Analysis (DMA). The shape memory performance of styrene copolymer with different cross-linking degrees was also evaluated. Results indicated that the shape memory polymer (SMP) was synthesized successfully. The Tg increased from 55°C to 80.7°C followed by increasing the gel content from 0% to 80% through increasing the dosage of cross-linking agent from 0% to 4%. Moreover, the SMP experienced good SME and the largest reversible strain of the SMP reached as high as 150%. When heating above Tg+30°C (different copolymers performed different Tg), the shape recovery speed of the copolymers increased with increasing the gel content. However, the recovery speed decreased with increasing the gel content at the same temperature of 95°C.
The Ohio State Univ. (USA) 65262M Effect of soft magnetic materials blend on the properties of polymer-bonded Terfenol-D composites
- M J Dapino
M. J. Dapino, The Ohio State Univ. (USA)
65262M
Effect of soft magnetic materials blend on the properties of polymer-bonded Terfenol-D
composites [6526-91]
Harbin Institute of Technology (China) and Dalian Univ. of Technology (China) POSTER SESSION 65262N Deformation behavior of polycrystalline Galfenol at elevated temperatures
- J Ou
J. Ou, Harbin Institute of
Technology (China) and Dalian Univ. of Technology (China)
POSTER SESSION
65262N
Deformation behavior of polycrystalline Galfenol at elevated temperatures [6526-44]
Japan) 65262P Derivation and simulation of an improved two-dimensional constitutive law for shape memory alloys
- F Narita
- Y Shindo
- F Saito
- Tohoku Univ
F. Narita, Y. Shindo, F. Saito, Tohoku Univ. (Japan)
65262P
Derivation and simulation of an improved two-dimensional constitutive law for shape
memory alloys [6526-94]
Univ. of Houston (USA) 65262R Synthesis and characterization of low cost magnetorheological (MR) fluids
- G Song
- H Gu
G. Song, H. Gu, Univ. of Houston (USA)
65262R
Synthesis and characterization of low cost magnetorheological (MR) fluids [6526-96]
Indian Institute of Technology Bombay (India) 65262T Resin flow monitoring in vacuum assisted resin transfer molding using optical fiber distributed sensor
- V K Sukhwani
- H Hirani
V. K. Sukhwani, H. Hirani, Indian Institute of Technology Bombay (India)
65262T
Resin flow monitoring in vacuum assisted resin transfer molding using optical fiber
distributed sensor [6526-98]
Ohio Aerospace Institute (USA) and NASA Glenn Research Ctr
- L J Ghosn
L. J. Ghosn, Ohio Aerospace Institute (USA) and NASA Glenn Research Ctr. (USA);
Defense Advanced Research Projects Agency (USA)
- Donald J Leo
Donald J. Leo, Defense Advanced Research Projects Agency (USA)
École Nationale Supérieure d'Arts et Métiers (France)
- Etienne Ferroelectrics
- Patoor
Ferroelectrics III
Etienne Patoor, École Nationale Supérieure d'Arts et Métiers (France)