Mechanical Properties of Polyester Toughened with Nano-Silica

The fabrication of nanocomposites has played role to the development of the nanotechnology and the technology of advanced composite materials. Thermoset polymers are used in engineering applications widely. Their mechanical properties can be change with adding particles. The mechanism of toughening polymers has been suggested recently by reinforcing well dispersed particles to the plain polymer. Nano-silica particles were added to thermoset polymer of polyester to evaluate their influence on the mechanical properties of the toughened polymer using both experimental and numerical methods. The Representative Volume Element (RVE) approach, which employs finite element models, has been developed to achieve that aim numerically for various types of nano-particle reinforcement ratios. In each case, the stiffness has been calculated with using the equivalent homogeneous material concept. Experimentally, toughened thermoset polymers of polyester reinforced with nano-silica were prepared with different particle content ratio. Several tests were conducted on the nanocomposite, and it was observed increasing nano-silica ratio caused increase in Young’s modulus and decrease in ductility.

Penerapan pembelajaran contekstual teaching and learning (CTL) berbantuan hands on activity untuk memahamkan siswa kelas VII-D SMPN 16 Malang pada materi perbandingan

The purpose of this research is revising the way of teaching for making student understand about mathematical ratio through Contextual Teaching and Learning by the use of Hands on Activity. The type of this research is a classroom action research with two cycles, the first cycle consists of four meetings and two meetings of the second cycle. Research’s subject is all students class VII-D SMPN 16 Malang, as many as 37 students, consist of 17 men and 20 women. The research activities comprise of learning, class discussions, presentations, and final test.. The data were collected from the result of cyclic final test, the assignment result of students on answering cyclic final test, the result observation about teacher and students activities, interview and field notes. The result indicate that cycle I learning achievement is 80 percent and there are 12 students who made mistakes on the material concept of find a quantity if ratio is known. In the second cycle the percentage of learning achievement is 89,18 percent of the number of students in the classroom and there are 13,88 percent of students still do not understand the material find quantity if ratio is known. Based on these results it can be concluded that the application of a Contextual Teaching and Learning (CTL) approach assisted by hands on activity can make students in grade VII-D SMPN 16 Malang understanding about topics of ratio.

A retrospective towards a biodegradable material concept for future Indonesian sustainable architecture

The awareness of the negative effect of the intensive usage of synthetic material has led to a significant phenomenon in recent global development. Moving forward to become a fully ready developed country, Indonesia shall move toward a more sustainable architecture for presenting a greener environment. Despite blessed with a distinctive collection of tropical material variants, reflected in its vernacular architecture, advanced material development must be invented to promote more progressive architecture in Indonesia. This research illustrates a new perspective regarding biodegradable material concepts for future Indonesian sustainable architecture. It is produced by respecting local and global development trends by using a bibliographic coupling and experimental methods in the laboratory to contribute to Indonesian sustainable architecture. A retrospective is aimed to highlight Indonesian biodegradable material and Indonesian vernacular architecture potency; it is presented as follows; (1) Understanding local–global trends in biodegradable architecture; (2) Indonesian potency on biodegradable materials; (3) A biodegradable material concept as an alternative perspective for Indonesian sustainable architecture. As a result, a new concept is proposed as an alternative for developing Indonesian biodegradable building materials. A more profound sustainable architecture is expected to engage local craftsmanship while highlighting unique biodegradable materials easily found in the surrounding environment, such as Indonesian Kombucha Tea and Indonesian Coffee.

PENGGUNAAN PEMETAAN KONSEP MATERI PELAJARAN OLEH GURU UNTUK MENINGKATKAN PEMAHAMAN BELAJAR SENI MUSIK SECARA DARING PADA PEMBELAJARAN SENI BUDAYA MASA PANDEMI COVID-19 DI KELAS X-2SMA NEGERI 1 SITIUNG

This study aims to describe the use of material concept mapping by teachers to help students understand theoretically music subject. The literature review used in this research is related to the notion of school instruction; learning during a pandemic; Learning of cultures and Arts (music) according to K13; and conceptual mapping of subject matter. This research belongs to a quantitative research using a descriptive analysis approach. Based on the research results during three online learning meetings in class X-2, it can be explained that the use of concept mapping of music art subject matter by the teachers based on the concept map made on the blackboard and PowerPoint slides has encouraged an increase in student understanding especially in terms of mastering the materials. The concept mapping made by teachers and assigned to students helps students better understand the subject matter of music in a more structured and organized way. Thus, it is in accordance with the theoretical ideas of the subject matter studied.

Extension of the Equivalent Material Concept to Compressive Loading: Combination with LEFM Criteria for Fracture Prediction of Keyhole Notched Polymeric Samples

This work analyzes, both theoretically and experimentally, the fracture process of square specimens weakened by keyhole notches and subjected to compressive stresses. Two materials are covered: general-purpose polystyrene (GPPS) and poly(methyl methacrylate) (PMMA). Firstly, the load-carrying capacity (LCC) of the specimens is determined experimentally. Then, by using the equivalent material concept (EMC) for compressive conditions coupled with the maximum tangential stress (MTS) and the mean stress (MS) criteria, the LCC of the notched specimens is predicted. The results show that by using the approach proposed in the present investigation, not only can the critical loads in the keyhole notched polymeric specimens be precisely predicted, but also the corresponding compressive critical stress of the two mentioned polymers can be successfully estimated.

DEVELOPING ORAL PREPARATION MATERIALS USING EXPERIENCE-BASED MEDIA

Preparation of oral presentation is one of the materials in the Indonesian language course. This material is a speaking skill material. This material helps students prepare for public speaking, such as providing health education to the public. The purpose of this study was to describe the preparation of experience-based oral presentation preparation materials.This research method uses qualitative research methods with data sources in the form of a book by Gorys Keraf entitled composition published by Nusa Indah and a book by Trianto entitled Designing an innovative-progressive learning model published by Kencana Prenada Media Group. The data in this study are the words, sentences or paragraphs in the two books. The data collection technique used by researchers was document study by collecting documents related to the preparation of materials and materials for oral presentation preparation. Meanwhile, for data analysis techniques, what the researchers did were: (1) data reduction. (2) displaying data by compiling relevant data, (3) drawing conclusions to get a meaning that scattered symptoms have deep meaning. The results of this study indicate that the preparation of oral presentation preparation materials using experience-based media produces a material concept map which in its presentation can be given examples through experience-based media. The existence of making a concept map for the preparation of oral presentation material makes the flow of oral presentation preparation clear and easy to understand, that in preparation for oral presentation there are three main components that must be done, namely 1) examining the problem where this point includes determining the intent, analyzing the listener and the situation, and selecting and narrowing the topic, 2) compiling a description. This point includes gathering material, drawing up a description outline, and describing it in detail, and 3) conducting an exercise. Powerful words are the key words at this point, that the speaker's knowledge of the topic and the needs of the listener, being able to position himself to be closer to the listener, speaking according to facts and speaking honestly, and having the same line of thought as the listener are components that must be mastered by the speaker. , so that the material conveyed to listeners really hits and impresses.

Estimation of Mode I Fracture of U-Notched Polycarbonate Specimens Using the Equivalent Material Concept and Strain Energy Density

Polycarbonate (PC) has a wide range of applications in the electronic, transportation, and biomedical industries. In addition, investigation on the applicability to use PC in superstrate photovoltaic modules is ongoing research. In this paper, PC is envisioned to be used as a material for structural components in renewable energy systems. Usually, structural components have geometrical irregularities, i.e., notches, and are subjected to severe mechanical loading. Therefore, the structural integrity of these components shall consider fracture analysis on notched specimens. In this paper, rectangular PC specimens were machined with straight U-notches having different radii and depths. Eight different notch radii with a depth of 6.0 mm were tested. In addition, three notch depths with a radius of 3.5 mm were considered. Quasi-static fracture tests were performed under displacement-controlled loading with a speed of 5 mm/min. Digital image correlation technique was used to capture the strain fields for un-notched and notched specimens. It was assumed that fracture occurs at the onset of necking. The equivalent material concept (EMC) along with the strain energy density criterion (SED) were employed to estimate the fracture load. The EMC-SED combination is shown to be an effective and practical tool for estimating the fracture load of U-notched PC specimens.

Critical Load Prediction in Notched E/Glass–Epoxy-Laminated Composites Using the Virtual Isotropic Material Concept Combined with the Average Strain Energy Density Criterion

This paper attempts to validate the application of the Virtual Isotropic Material Concept (VIMC) in combination with the average strain energy density (ASED) criterion to predict the critical load in notched laminated composites. This methodology was applied to E/glass–epoxy-laminated composites containing U-notches. For this purpose, a series of fracture test data recently published in the literature on specimens with different notch tip radii, lay-up configurations, and a number of plies were employed. It was shown that the VIMC–ASED combined approach provided satisfactory predictions of the last-ply failure (LPF) loads (i.e., critical loads).