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1. Enhancement of Relative Permittivity of Material with Metallic Inclusions – Experimental Verification

   https://doi.org/10.1109/SoutheastCon51012.2023.10115156  

   Saha, Arun Kumar; Pendleton, Walker (April 2023, IEEE)

   In this project, it was shown by simulation that the permittivity of a material could be enhanced by embedding metal inclusions in the host material. Later, a series of systematic experiments were carried out with free space material measurement equipment/system to demonstrate the enhancement of permittivity with circular metal patches printed periodically on a host material to validate the simulation results. 

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2. Toward an accommodation account of deaccenting under nonidentity

   https://doi.org/10.3765/elm.1.4875  

   Geiger, Jeffrey; Xiang, Ming (July 2021, Experiments in Linguistic Meaning)

   Beltrama, Andrea; Schwarz, Florian; Papagragou, Anna (Ed.)

   Two competing models attempt to explain the deaccentuation of antecedent nonidentical discourse-inferable material (e.g., Bach wrote many pieces for viola. He must have LOVED string instruments). One uses a single grammatical constraint to license deaccenting for identical and nonidentical material. The second licenses deaccenting grammatically only for identical constituents, whereas deaccented nonidentical material requires accommodation of an alternative antecedent. In three experiments, we tested listeners’ preferences for accentuation or deaccentuation on nonidentical inferable material in out-of-the-blue contexts, supportive discourse contexts, and in the presence of the presupposition trigger too. The results indicate that listeners by default prefer for inferable material to be accented, but that this preference can be mitigated or even reversed with the help of manipulations in the broader discourse context. By contrast, listeners reliably preferred for repeated material to be deaccented. We argue that these results are more compatible with the accommodation model of deaccenting licensing, which allows for differential licensing of deaccentuation on inferable versus repeated constituents and provides a principled account of the sensitivity of accentuation preferences on inferable material to broader contextual manipulations. 

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3. Additive Manufacturing of Polymer Matrix Composite Materials with Aligned or Organized Filler Material: A Review

   https://doi.org/10.1002/adem.202001002  

   Niendorf, Karl; Raeymaekers, Bart (January 2021, Advanced Engineering Materials)

   The ability to fabricate polymer matrix composite materials with continuous or discontinuous filler material, oriented in a user‐specified direction, enables implementing designer material properties, such as anisotropic mechanical, thermal, and electrical properties. Conventional fabrication methods rely on a mold, which limits specimen geometry and is difficult to implement. In contrast, additive manufacturing, including fused filament fabrication or fused deposition modeling, direct ink writing, or stereolithography, combined with a method to align filler material such as a mechanical force or an electric, magnetic, shear force, or ultrasound wave field, enables 3D printing polymer matrix composite material specimens with complex geometry and aligned filler material, without the need for a mold. Herein, we review the combinations of fabrication and filler material alignment methods used to fabricate polymer matrix composite materials, in terms of operating and design parameters including size, resolution, print speed, filler material alignment time, polymer matrix and filler material requirements, and filler manipulation requirements. The operating envelope of each fabrication method is described and their advantages, disadvantages, and limitations are discussed. Finally, different combinations of 3D printing and filler material alignment methods in the context of important engineering applications, such as structural materials, flexible electronics, and shape‐changing materials, are illustrated. 

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4. 3-D PRINTING OF DIELECTRIC ELECTROACTIVE POLYMER ACTUATORS AND CHARACTERIZATION OF DIELECTRIC FLEXIBLE MATERIALS

   Gonzalez, David; Newell, Brittany; Garcia, Jose; Noble, Lucas; Mamer, Trevor (October 2018, ASME Conference on Smart Materials, Adaptive Structures, and Intelligent Systems (SMASIS))

   Dielectric electroactive polymers are materials capable of mechanically adjusting their volume in response to an electrical stimulus. However, currently these materials require multi-step manufacturing processes which are not additive. This paper presents a novel 3D printed flexible dielectric material and characterizes its use as a dielectric electroactive polymer (DEAP) actuator. The 3D printed material was characterized electrically and mechanically and its functionality as a dielectric electroactive polymer actuator was demonstrated. The flexible 3-D printed material demonstrated a high dielectric constant and ideal stress-strain performance in tensile testing making the 3-D printed material ideal for use as a DEAP actuator. The tensile stress- strain properties were measured on samples printed under three different conditions (three printing angles 0°, 45° and 90°). The results demonstrated the flexible material presents different responses depending on the printing angle. Based on these results, it was possible to determine that the active structure needs low pre-strain to perform a visible contractive displacement when voltage is applied to the electrodes. The actuator produced an area expansion of 5.48% in response to a 4.3 kV applied voltage, with an initial pre-strain of 63.21% applied to the dielectric material. 

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5. Analytical Study of Nonlinear Flexural Vibration of a Beam with Geometric, Material and Combined Nonlinearities

   https://doi.org/10.3390/vibration7020025  

   Madhuranthakam, Yoganandh; Chakrapani, Sunil Kishore (June 2024, Vibration)

   This article explores the nonlinear vibration of beams with different types of nonlinearities. The beam vibration was modeled using Hamilton’s principle, and the equation of motion was solved using method of multiple time scales. Three models were developed assuming (a) geometric nonlinearity, (b) material nonlinearity and (c) combined geometric and material nonlinearity. The material nonlinearity also included both third and fourth nonlinear elasticity terms. The frequency response equation of these models were further evaluated quantitatively and qualitatively. The models capture the hardening effect, i.e., increase in resonant frequency as a function of forcing amplitude for geometric nonlinearity, and the softening effect, i.e., decrease in resonant frequency for material nonlinearity. The model is applied on the first three bending modes of the cantilever beam. The effect of the fourth-order material nonlinearity was smaller compared to the third-order term in the first mode, whereas it is significantly larger in second and third mode. The combined nonlinearity models shows a discontinuous frequency shift, which was resolved by utilizing a set of transition assumptions. This results in a smooth transition between the material and geometric zones in amplitude. These parametric models allow us to fine tune the nonlinear response of the system by changing the physical properties such as geometry, linear and nonlinear elastic properties. 

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