scholarly journals Measurement of Shear Strain Field in a Soft Material Using a Sensor System Consisting of Distributed Piezoelectric Polymer Film

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3484 ◽  
Author(s):  
Fengyu Li ◽  
Yasuhiro Akiyama ◽  
Xianglong Wan ◽  
Shogo Okamoto ◽  
Yoji Yamada
Keyword(s):  
Shear Strain ◽  
Strain Field ◽  
Polyvinylidene Fluoride ◽  
Three Dimensional ◽  
Soft Materials ◽  
Soft Material ◽  
Sensor System ◽  
Skin Damage ◽  
Skin Contact ◽  
Sensing Model

Measurement of the internal stress and strain distributions within soft materials is necessary in the field of skin contact safety. However, conventional interactive force sensors cannot efficiently obtain or estimate these distributions. Herein, a shear strain sensor system consisting of distributed built-in piezoelectric polyvinylidene fluoride (PVDF) polymer films was developed to measure the internal shear strain field of a soft material. A shear strain sensing model was mathematically established, based on the piezoelectricity and mechanical behavior of a bending cantilever beam, to explain the sensing principle. An experiment in three-dimensional measurement of the shear strain distribution within an artificial skin was designed and conducted to assess the sensitivity of the sensing model. This sensor system could visualize the shear strain field and was sensitive to different contact conditions. The measurement results agreed well with the results of numerical simulation of the substrate, based on contact mechanics. The proposed sensor system was confirmed to provide a new sensing method for the field of shape analysis. The sensor system can be applied to develop sufficiently sensitive electronic skin and can significantly contribute to skin damage analysis and skin contact safety assessment.

scholarly journals Discovery of deformation mechanisms and constitutive response of soft material surrogates of biological tissue by full-field characterization and data-driven variational system identification

2020 ◽  
Author(s):  
Z. Wang ◽  
J.B. Estrada ◽  
E.M. Arruda ◽  
K. Garikipati
Keyword(s):  
System Identification ◽  
Mathematical Models ◽  
Biological Tissue ◽  
Three Dimensional ◽  
Soft Materials ◽  
Soft Material ◽  
Data Driven ◽  
Deformation Tensor ◽  
Variational System ◽  
Soft Biological Tissue

AbstractWe present a novel, fully three-dimensional approach to soft material characterization and constitutive modeling with relevance to soft biological tissue. Our approach leverages recent advances in experimental techniques and data-driven computation. The experimental component of this approach involves in situ mechanical loading in a magnetic field (using MRI), yielding the entire deformation tensor field throughout the specimen regardless of the possible irregularities in its three-dimensional shape. Characterization can therefore be accomplished with data at a reduced number of deformation states. We refer to this experimental technique as MR-u. Its combination with powerful approaches to inverse modelling, specifically methods of model inference, would open the door to insightful mechanical characterization for soft materials. In recent computational advances that answer this need, we have developed new, data-driven inverse techniques to infer the model that best explains the physics governing observed phenomena from a spectrum of admissible ones, while maintaining parsimony of representation. This approach is referred to as Variational System Identification (VSI). In this communication, we apply the MR–u approach to characterize soft biological tissue and polymers, and using VSI, we infer the physically best-suited and parsimonious mathematical models of their mechanical response. We demonstrate the performance of our methods in the face of noisy data with physical constraints that challenge the identification of mathematical models, while attaining high accuracy in the predicted response of the inferred models.

scholarly journals A Built-in Sensor System Monitoring Internal Shear Strain and Stress Distribution for Soft Materials

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Fengyu Li ◽  
Yasuhiro Akiyama ◽  
Xianglong Wan ◽  
Shogo Okamoto ◽  
Yoji Yamada
Keyword(s):  
Stress Distribution ◽  
Shear Strain ◽  
Soft Materials ◽  
Sensor System ◽  
System Monitoring

scholarly journals Construction of a Three-Dimensional BaTiO3 Network for Enhanced Permittivity and Energy Storage of PVDF Composites

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3585
Author(s):  
Xueqing Bi ◽  
Lujia Yang ◽  
Zhen Wang ◽  
Yanhu Zhan ◽  
Shuangshuang Wang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Polyvinylidene Fluoride ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Sol Gel ◽  
Three Dimensional ◽  
Low Dielectric ◽  
Energy Storage Properties ◽  
Discharge Energy Density ◽  
Pure Pvdf

Three-dimensional BaTiO3 (3D BT)/polyvinylidene fluoride (PVDF) composite dielectrics were fabricated by inversely introducing PVDF solution into a continuous 3D BT network, which was simply constructed via the sol-gel method using a cleanroom wiper as a template. The effect of the 3D BT microstructure and content on the dielectric and energy storage properties of the composites were explored. The results showed that 3D BT with a well-connected continuous network and moderate grain sizes could be easily obtained by calcining a barium source containing a wiper template at 1100 °C for 3 h. The as-fabricated 3D BT/PVDF composites with 21.1 wt% content of 3D BT (3DBT–2) exhibited the best comprehensive dielectric and energy storage performances. An enhanced dielectric constant of 25.3 at 100 Hz, which was 2.8 times higher than that of pure PVDF and 1.4 times superior to the conventional nano–BT/PVDF 25 wt% system, was achieved in addition with a low dielectric loss of 0.057 and a moderate dielectric breakdown strength of 73.8 kV·mm−1. In addition, the composite of 3DBT–2 exhibited the highest discharge energy density of 1.6 × 10−3 J·cm−3 under 3 kV·mm−1, which was nearly 4.5 times higher than that of neat PVDF.

scholarly journals Investigation of a Three-Dimensional Micro-Scale Sensing System Based on a Tapered Self-Assembly Four-Cores Fiber Bragg Grating Probe

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2824 ◽  
Author(s):  
Kunpeng Feng ◽  
Jiwen Cui ◽  
Xun Sun ◽  
Hong Dang ◽  
Tangjun Shi ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Self Assembly ◽  
Three Dimensional ◽  
Critical Length ◽  
Bragg Grating ◽  
Manufacturing Method ◽  
Micro Scale ◽  
Sensing Model ◽  
Shift Point ◽  
Better Than

Three-dimensional micro-scale sensors are in high demand in the fields of metrology, precision manufacturing and industry inspection. To extend the minimum measurable dimension and enhance the accuracy, a tapered four-cores fiber Bragg grating (FBG) probe is proposed. The sensing model is built to investigate the micro-scale sensing characteristics of this method and the design of the tapered stylus is found to influence the accuracy. Therefore, a π/2 phase-shift point is introduced into the FBGs comprised in the probe to suppress spectrum distortion and improve accuracy. Then, the manufacturing method based on capillary self-assembly is proposed to form the probe and the critical length to form a square array for four cylindrical fibers is verified to be effective for the tapered fibers. Experimental results indicate that the design of the tapered stylus can extend the minimum measurable dimension by twofold and has nearly no influence on its sensitivity. The three-dimensional measurement repeatability is better than 31.1 nm and the stability is better than 200 nm within once measuring process. Furthermore, the measurement precision of the three-dimensional micro-scale measurement results is less than 150 nm. It would be widely used in measuring micro-scale features for industry inspection or metrology.

scholarly journals A new methodology to identify minimum strain anatomical lines based on 3-D digital image correlation

2017 ◽  
Vol 8 (2) ◽  
pp. 337-347 ◽  
Author(s):  
Jorge Barrios-Muriel ◽  
Francisco Javier Alonso Sánchez ◽  
David Rodríguez Salgado ◽  
Francisco Romero-Sánchez
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Strain Field ◽  
Three Dimensional ◽  
Wearable Devices ◽  
Plane Motion ◽  
Human Motion ◽  
The Body ◽  
Image Correlation ◽  
Minimum Deformation

Abstract. Today there is continuous development of wearable devices in various fields such as sportswear, orthotics and personal gadgets, among others. The design of these devices involves the human body as a support environment. Based on this premise, the development of wearable devices requires an improved understanding of the skin strain field of the body segment during human motion. This paper presents a methodology based on a three dimensional digital image correlation (3D-DIC) system to measure the skin strain field and to estimate anatomical lines with minimum deformation as design criteria for the aforementioned wearable devices. The errors of displacement and strain measurement related to 3-D reconstruction and out-of-plane motion are investigated and the results are acceptable in the case of large deformation. This approach can be an effective tool to improve the design of wearable devices in the clinical orthopaedics and ergonomics fields, where comfort plays a key role in supporting the rehabilitation process.

scholarly journals Densely distributed and real-time scour hole monitoring using piezoelectric rod sensors

2019 ◽  
Vol 22 (16) ◽  
pp. 3395-3411
Author(s):  
Morgan L Funderburk ◽  
Shieh-Kung Huang ◽  
Chin-Hsiung Loh ◽  
Kenneth J Loh
Keyword(s):  
Monitoring System ◽  
Fundamental Frequency ◽  
Polyvinylidene Fluoride ◽  
Three Dimensional ◽  
Piezoelectric Element ◽  
Direct Calculation ◽  
Thin Strip ◽  
Scour Depth ◽  
Scour Monitoring ◽  
Dry Conditions

This study aims to validate a piezoelectric driven-rod scour monitoring system that can sense changes in scour depth along the entire rod at its instrumented location. The proposed sensor is a polymeric slender rod with a thin strip of polyvinylidene fluoride that runs through its midline. Extraction of the fundamental frequency allows the direct calculation of the exposed length (or scour depth) of the slender rod undergoing fluid flow excitation. First, laboratory validation in dry conditions is presented. Second, hydrodynamic testing of the sensor system in a soil-bed flume is discussed. Each rod was installed using a three-dimensional-printed footing designed for ease of installation and stabilization during testing. The sensors were installed in a layout designed to capture symmetric scour conditions around a scaled pier. In order to analyze the system out of steady-state conditions, water velocity was increased in stages during testing to induce different degrees of scour. As ambient water flow excited the portion of the exposed rods, the embedded piezoelectric element outputted a time-varying voltage signal. Different methods were then employed to extract the fundamental frequency of each rod, and the results were compared. Further testing was also performed to characterize the relationship between frequency outputs and flow velocity, which were previously thought to be independent. In general, the proposed driven-rod scour monitoring system successfully captured changing frequencies under varied flow conditions.

scholarly journals Mechanical properties of magnetic gels containing rod-like composite particles

2019 ◽  
Vol 377 (2143) ◽  
pp. 20180218 ◽  
Author(s):  
Mariem M. Abrougui ◽  
Modesto T. Lopez-Lopez ◽  
Juan D. G. Duran
Keyword(s):  
Mechanical Properties ◽  
Magnetic Particles ◽  
Three Dimensional ◽  
Heterogeneous Systems ◽  
Soft Materials ◽  
Polymer Chains ◽  
Composite Particles ◽  
Magnetite Particles ◽  
Magneto Rheological ◽  
Mr Effect

Magnetic gels (ferrogels) are heterogeneous systems structured at the nanoscale that contains magnetic particles dispersed in three-dimensional networks of polymer chains. In the present work, the magnetic particles were synthesized with a core–shell structure, consisting of sepiolite particles covered by magnetite nanoparticles. These composite particles had a rod-like shape with a high aspect ratio. The obtained sepiolite–magnetite particles showed a high enough susceptibility and saturation magnetization. The magneto-rheological (MR) properties, and the intensity of the MR effect, of aqueous suspensions of the synthesized particles were studied. The particles, functionalized by adsorption of alginate molecules, were imbedded in alginate hydrogels to get homogeneous soft materials. The particles were linked to the polymer chains as the knots in a network and dominated in a great extent the mechanical properties of the materials. After determining the optimal compositions of the ferrogels, their viscoelastic properties were measured in the absence/presence of magnetic fields. The results pointed out that the MR effect provided by the clay–magnetite particles was considerably more intense than those achieved in ferrogels that contain spherical magnetic microparticles. Therefore, the imbedding of rod-shaped magnetic particles in hydrogels allows controlling the mechanical properties in a wider range than in conventional ferrogels. This article is part of the theme issue ‘Heterogeneous materials: metastable and non-ergodic internal structures’.

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