Geometrically nonlinear analysis of laminated elastic structures

This final technical report contains three parts: Part 1 deals with the 2-D shell theory and its element formulation and applications. Part 2 deals with the 3-D degenerated element. These two parts constitute the two major tasks that were completed under the grant. Another related topic that was initiated during the present investigation is the development of a nonlinear material model. This topic is briefly discussed in Part 3. To make each part self-contained, conclusions and references are included in each part. In the interest of brevity, the discussions presented are relatively brief. The details and additional topics are described in the references cited

Thermal characterization of plain and carbon nanotube reinforced syntactic foams

Syntactic foams are composite materials in which the matrix phase is reinforced with hollow particles called microballoons. They possess properties such as low moisture absorption, low thermal conductivity and high damage tolerance because of their compositions. Traditionally, syntactic foams are used for many high strength applications and as insulating materials. But for applications demanding better heat dissipation from syntactic foam, conductive filler materials need to be added while maintaining its property of low density. Carbon nanotubes although extremely conductive, have issues of agglomeration in the matrix. In this research, a new approach to the problem of dispersion of nanotubes was attempted by growing the nanotubes on the surface of glass microballoons. S22 glass microballoons with low density were used in this work. Chemical vapor deposition was used for growing nanotubes on the microballoons using nickel as a catalyst. Nickel coating on microballoons was obtained via an electroless plating process. Observations were made on the nickel coating and nanotube growth processes with the help of a Scanning Electron Microscope (SEM). Thickness of the catalyst layer, growth temperature, gas flow rates and the quality of palladium activation were found to be the determining steps for nanotube growth. Transmission Electron Microscopy (TEM) was used to characterize the growth of nanostructures. Multi-walled carbon nanotubes of 6 – 20 nm were grown in this research. The thermal conductivity of nanotube-grown syntactic foam was tested on a Flashline thermal analyzer utilizing a flash method. For comparison purposes, plain and nanotube-mixed syntactic foams were fabricated and tested for conductivity. The effect of amount of nanotube and microballoon on the conductivity of the material was studied. The conductivity increments were low due to thermal boundary resistance occurring at the interface of nanotubes and resin. Nanotube-grown foams increase the thermal conductivity of plain syntactic foam by 86%, as opposed to nanotube-mixed ones which showed lower conductivity values than plain syntactic foam. TEM images showed that the mixing method had nanotubes being highly agglomerated whereas the growing method was successful in creating a well dispersed network of nanotubes

Unethical publishing behavior of an Indian predatory journal: a case study

Abstract: the study was intended to know the unethical publishing behavior of one of the Indian predatory journals with a special reference to acceptance of plagiarized works for publication. It’s found in a study that editors do not conduct review for articles to assess the quality of publications and provide submitters with a no proper guidelines on plagiarism and reference styles as to improve the quality of research works. This will clearly indicates the greediness of making money of publishers from authors. Noticing these type unethical publishing behaviors of predatory journals researcher considers predatory journals are more of researchers’ deceptive journal than researchers’ assistive journal. The major findings of the study like higher extent of similar content in abstract and conclusion of 24 research publication, acceptance of 13 manuscripts with more than 80% similar content without citation and acceptance of less than 2 pages paper full of plagiarism for publications are the best instances as to show how ignorantly predatory journals are misusing their authority of publication in India. Hence, researcher strongly feels National Science Library should initiate measures to revoke the assigned ISSN given by them to curb the illegitimate publications

Thermal and Mechanical Response of Inner Cone Sample of ZrB₂-SiC Ceramic under Arc-Jet Conditions

Under arc-jet test conditions, ZrB2-SiC ceramic will undergo high temperature oxidation and develop an external glassy layer (SiO2), zirconia sub-layer (ZrO2) and SiC-depleted diboride layer (ZrB2). This study relates to finite element modeling of the effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramic under arc-jet test conditions. A steady-state heat transfer FE method was employed to conduct the heat transfer analysis to obtain the temperature distribution in the inner body of the cone. The surface thermal conditions available in the literature were used in the heat transfer analysis. The resulting temperature distribution in the inner body of the cone is then applied to the thermomechanical finite element analysis to calculate the thermal stress distribution. The results show that the oxide layers affect both thermal and mechanical response of the ZrB2-SiC ceramic under arc-jet high temperature test conditions. Due to the mismatch of material properties between the bulk ZrB2-SiC and its new products after oxidation, the outer oxide layers constrain the thermal deformation of the inner bulk ZrB2-SiC thereby putting it in compression and outside oxide layers in tension

Composite Structures using Asphalt Based Roofing Scrap Materials: EIERA -- Final Report

The uses of recycled materials in composites provide the potential for large cost savings and a solution to the ever-growing disposal problem. Shingles contain petroleum based binders and fillers, which used as a valuable resource in composite production. Composites offer inherent advantages over traditional materials in regard to corrosion resistance, design flexibility and extended service life. Use of scrap-roofing shingles as a core material in glass fiber reinforced composite materials offer potential low cost composite products such as sound barrier system, railroad ties and other building materials including blocks. In the present work, processes have been developed for shredding scrap roof shingles, for making shingle blocks, and for filling hollow composite tubes. Mechanical testing was performed to compare the performance of filled composite tubes to hollow tubes and oak wood beams. Filled tubes show improvement in ultimate flexural strength by preventing buckling and crushing. Tests were also conducted to evaluate the sound attenuation capability of recycled shingle walls. It was observed that the mean sound level at the backside of the wall, measured in decibels, was greatly reduced and shows potential use for recycled shingles in a sound barrier system. University of Missouri-Rolla has collaborated with Future Tek Inc. and Lemay Center for Composites Technology for successful completion of this project. The economic benefits are truly immense. This project will impact the community by diverting thousands of tons of shingles into usable products with a real economic impact

Behavior of EB FRP Masonry Bond under Service Temperature

The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability by considering exposure to harsh environmental conditions and testing the specimens after exposure, rather than testing bond performance during exposure. The influence of directly applying temperature on bond behavior represents an open topic that needs to be investigated in more detail. This study is one of the first studies to investigate the bond behavior when the composite is subjected to tension force simultaneously with applying temperature. The temperatures considered in this study were at freezing, ambient, and high temperature, which are more representative of structural elements under field conditions. A total of 16 specimens were strengthened and tested under single-lap direct shear. The key parameters investigated include (a) the type of fiber [laminate carbon vs. wet layup glass] (b) the level of temperature applied on specimen, including ambient condition 21°C (70 °F), freeze condition -18 °C (0 °F) and hot weather 49 °C (120 °F), and (c) the exposure regime (direct exposure during loading process vs. loading after exposure). Most of the specimens were subjected to tension force simultaneously with applying temperature, and the other specimens were later tested after exposure to the heating and cooling cycles. These cycles are proposed to simulate 20 years of the typical in-situ weather conditions in the Central United States. The results showed that overall the EB strengthening systems exhibited good performance when subjected to cycles of heating and cooling prior to testing. High reduction of FRP-epoxy bond properties was up to 59% when exposed to high service temperatures. Different modes of failure were observed such as debonding at fiber-matrix interface and debonding due to shearing in laminate

Slim U-Net: Efficient Anatomical Feature Preserving U-net Architecture for Ultrasound Image Segmentation

We investigate the applicability of U-Net based models for segmenting Urinary Bladder (UB) in male pelvic view UltraSound (US) images. The segmentation of UB in the US image aids radiologists in diagnosing the UB. However, UB in US images has arbitrary shapes, indistinct boundaries and considerably large inter- and intra-subject variability, making segmentation a quite challenging task. Our study of the state-of-the-art (SOTA) segmentation network, U-Net, for the problem reveals that it often fails to capture the salient characteristics of UB due to the varying shape and scales of anatomy in the noisy US image. Also, U-net has an excessive number of trainable parameters, reporting poor computational efficiency during training. We propose a Slim U-Net to address the challenges of UB segmentation. Slim U-Net proposes to efficiently preserve the salient features of UB by reshaping the structure of U-Net using a less number of 2D convolution layers in the contracting path, in order to preserve and impose them on expanding path. To effectively distinguish the blurred boundaries, we propose a novel annotation methodology, which includes the background area of the image at the boundary of a marked region of interest (RoI), thereby steering the model's attention towards boundaries. In addition, we suggested a combination of loss functions for network training in the complex segmentation of UB. The experimental results demonstrate that Slim U-net is statistically superior to U-net for UB segmentation. The Slim U-net further decreases the number of trainable parameters and training time by 54% and 57.7%, respectively, compared to the standard U-Net, without compromising the segmentation accuracy.Comment: Accepted in 9th ACM International Conference on Biomedical and Bioinformatics Engineering (ICBBE) 2022 http://www.icbbe.com

EFFECT OF CULTURAL CONDITION ON EVALUATION OF HEPATOPROTECTIVE ACTIVITY OF METHANOLIC BARK EXTRACT OF ANOGEISSUS LATIFOLIA ON ETHANOL-INDUCED HEPATOTOXICITY

Objective: Geographical location has a great importance on phytoconstituents content in plants. The present study was aimed to understand the impact of soil nature of geographical zone on evaluation of hepatoprotective activity Anogeissus latifolia (AL), (family: Combretaceae) methanolic bark extract on ethanol-induced hepatotoxicity in Wistar rats.Methods: Soil sample was collected and analyzed for various physicochemical properties. Atomic absorption spectrophotometer was used for determination of heavy metals present in soil sample. Thereafter, liver damage was produced by ethanol (3.76 g/kg p.o). The plant extract was administered orally for 25 days. At the end of the study, the biochemical parameters were investigated. Silymarin was used as a standard. Furthermore, histopathology was carried out and characterized by severe vacuolar, cytoplasmic degeneration, and hepatic necrosis. Finally, the impact of soil parameters is correlated with the evaluated study.Results: Analyzed soil sample showed pH is acidic (pH=5.48) and presence of higher amount of iron (Fe), copper (Cu), and zinc (Zn) (77.37 mg/kg, 10.87 mg/kg, and 19.26 mg/kg, respectively) whereas other metals such as nickel, chromium, cadmium, and lead are present in less content. Thereafter, treatment of animals with methanolic extract of AL bark significantly (p<0.05) decrease the levels of serum glutamic oxaloacetic transaminase in serum which is an indicative of hepatoprotective activity. Also brought down the level of serum glutamic pyruvic transaminase significantly (p<0.05 in 200 mg/kg b.w. and 400 mg/kg b.w. doses, respectively). Various parameters physical parameters, cholesterol level, and total protein were estimated. Histopathology studies and triglycerides also were indicative of hepatoprotective property.Conclusion: Finally, the results concluded that the presence of higher amount of Fe and Zn helps to get the significant results of the present investigation which has great impact on liver protection and the selected plant extract showed dose-dependent significant hepatoprotective effect against ethanol-induced hepatotoxicity in Wistar rats