Grade Material Research Articles

Optimization of Separation Parameters for a Pneumatic Separation Device for Plastic Evidence at Explosion Sites

AbstractExtracting and recovering plastic evidence at explosion sites is important for police investigations. Pneumatic separation is an efficient recovery method that is simple and environmentally friendly. To improve the accuracy of material separation, it is necessary to fully understand the influence of internal flow fields and structural design when using a material evidence classification device at explosion sites. In this study, a combination of a simulation and experiments is used. The results from the simulation are used to design a pneumatic separation device that is applied to explosive separation experiments. The grade and recovery rate of the plastic materials are excellent, which confirms the suitability of the device to classify plastic evidence at explosion sites.

DIORAMA: AS A LEARNING MEDIA FOR SCIENCE AND SOCIAL STUDIES (IPAS) ON ECOSYSTEM MATERIAL IN GRADE IV OF SDI CENDEKIA ASSALAM BANGILAN

Teaching Science and Social Studies (IPAS) in elementary schools often faces challenges in delivering abstract concepts such as ecosystems. Conventional teaching methods, which are less interactive, make it difficult for students to understand the relationships between ecosystem components. This study aims to examine the effectiveness of diorama media in improving students' understanding of ecosystem material in Grade IV of SDI Cendekia Assalam Bangilan. The research used a quantitative approach with a quasi-experimental design, involving 27 students in the experimental group using diorama media and 25 students in the control group using conventional teaching methods. Data were collected through pre-tests and post-tests and analyzed using the t-test. The results showed that the average post-test score of the experimental group was higher (85.4) compared to the control group (73.8). Statistical analysis indicated a significant difference between the two groups (p < 0.05), demonstrating that diorama media is effective in enhancing students' understanding of ecosystem concepts. These findings support constructivist learning theory, which emphasizes the importance of visual experiences and interaction in learning. This study suggests that diorama media should be widely applied to other materials requiring concrete visualization. Additionally, further research can explore the impact of diorama media on other skills such as critical thinking or student collaboration.

Functionally Graded Impact Attenuator Using Bonded Construction

ABSTRACTAutomotive collisions are one of the major causes of death in the European Union, especially in childhood and adolescence. However, improvements in vehicle safety cannot be achieved only by increasing the size and dimensions of the structures, as this demands more materials and more costly manufacturing processes, which leads to an increased resource expenditure and lowered sustainability. Moreover, the increase of the structure size raises the vehicle's weight, leading to added fuel consumption, which cannot be accepted considering modern environmental regulations. To solve these issues, the application of bonded joints using the combination of several adherends materials, such as steel and aluminium alloys and fibber‐reinforced polymers with crash‐resistant adhesives presents itself as a novel solution, allowing to attain enhanced joint strength, energy absorption and weight reduction. The present works introduce a novel concept of an impact attenuator using bonded, geometrically optimized using the concept of functionally graded adherends to maximize energy absorption by ensuring that a load‐bearing path is kept during impact, converting the impact energy into the plastic deformation of panels with variable mechanical properties, tailored to withstand specific load cases, fulfilling a gap in the literature regarding impact absorption devices that combines graded materials and bonded construction. The results obtained present an increase in the energy absorption values of the graded impact attenuators above 200% when compared to the homogenous materials.

Nondestructive Testing of Polymer Aging Based on Room-Temperature Phosphorescence.

Polymeric room-temperature phosphorescence (RTP) materials have attracted much attention due to their advantages of easy processing and excellent luminescent properties. However, it is still a challenge to obtain industrial production grade material through simple and green processing strategies. Herein, through the codoping strategy, different phosphors were embedded into nylon, a kind of polymer matrix, to obtain a series of highly efficient RTP materials without any organic solvents, for which the phosphorescence lifetime and brightness could reach 628.8 ms and 14 cd/m2, respectively. Besides, we found that the photophysical properties of these RTP materials varied greatly among different types of nylon matrix, owing to the divergence in the number of hydrogen bonding "sites". The superiority of the injection molding processing strategy enables the preparation of RTP materials to achieve desolvation, which could also be processed into any complex and desiring shape. Significantly, nylon can affect molecular chain changes due to aging and other problems, so that these RTP materials are considered as potential nondestructive testing for nylon product aging levels. This strategy also paves the way for the development of large-scale, eco-friendly, and practical application RTP materials and provides new ideas to industrialized preparation of long-lived RTP materials in the future.

Development of Articulate Storyline-Based Media for Momentum and Impulse Material in Grade X Senior High Schools, Indonesia

This study aims to develop an android application-based learning media that is literacy-oriented on Momentum and Impulse material and can be run on most devices owned by students. The creation goes through several stages in its formation. Through an application on a computer or laptop called Articulate Storyline, it is developed in such a way as to become a learning media that can be used in everyday learning. With the development model used is the ADDIE model. This model was chosen because it has research steps that are systematically arranged. The steps of the ADDIE research and development procedure consist of five stages, namely Analyze, Design, Develop, Implementation and Evaluation. Which is intended for teachers and students of State High School (SMAN) 2 Pare and State Islamic High School (MAN) Paser with supporting data for material and media validation tests. The results of the study produced 91% for the media validation test and 83% for the results of the material validation test and it can be said that the learning media is very suitable for use. While the test results for teachers and students at MAN Paser and also SMAN 2 Pare each showed 90% and 94% for teachers and 90% and 89% for students.

Application Of Problem Based Learning Model In Civics Learning On Central Government Structure Material In Grade IV Of Pabelan Kartasura State Elementary School

This research is entitled "Application of the Problem Based Learning Model in Civics Learning on Central Government Structure Material Class IV Sdn Pabelan Kartasura" This research aims to analyze the application of the Problem Based Learning (PBL) learning model in Civics Education (PKn) learning on Central Government Structure material in class IV SDN Pabelan, Kartasura. This research is motivated by the need to increase students' active participation and in-depth understanding of abstract material. The PBL model also encourages students to be more active in discussing, working together, and solving problems independently or in groups. The research results show that the application of the PBL model can increase student involvement in the learning process, critical thinking skills, and student learning outcomes. The research methods used are direct observation in class, interviews with teachers, and documentation. The observation results show that Civics learning in class IV at SDN Pabelan 03 has been implemented in accordance with the learning plan prepared. Teachers use lecture, question and answer and group discussion methods to improve students' understanding of the material. Learning evaluation is carried out through written tests and student attitude assessments. Obstacles found included limited time and lack of student involvement in several discussion activities. The conclusion from this observation is that Civics learning at SDN Pabelan 03 has gone well, but innovation is needed in learning methods and media to improve the quality of learning.

Characterization of the effect of creep and multiaxial loading situations on fatigue of short fiber reinforced thermoplastics

The present study is concerned with an experimental study into the effect of superimposed creep deformation, varying local fiber orientation distributions, and more complex multiaxial stress states on the fatigue of short fiber reinforced thermoplastics. The cross-interaction of these effects is a relevant feature in all fields of applications of short fiber composites since molding related variations of the local fiber orientation states cannot be avoided for injection molded structures. Long term loading will result in a combined occurrence of fatigue and creep and thus an interaction of the related effects. The study is based on a short glass fiber reinforced polyamide 66 as reference material which is a common material grade in many automotive applications. A basic characterization is performed by means of tensile and DMA experiments. Subsequently, creep and creep fatigue experiments are performed at ambient and elevated temperatures. In order to include the effects of locally varying fiber orientation situations and locally multiaxial loading situations, the coupon experiments are complemented by experiments on breadboard specimens featuring notches, holes, and structural component related external geometries. Superimposed creep deformation might accelerate fatigue failure, however, for notched specimens might also result in an increased fatigue lifetime due to creep-induced stress relief at the notch roots. The results reveal that care has to be taken when transferring the results on idealized coupon specimens to generalized, realistic problems. The results also serve as a development and validation data base for a continuum damage mechanics material model presented in an oncoming contribution.

Implementation of the Problem Posing Model to Improve Learning Outcomes of Grade 5 Students on the Human Digestive System Material

The problem posing learning model is a method that can increase student activity and involvement in learning. The problem posing model encourages students to ask questions, solve problems, and discuss collaboratively, so that they are able to build a deeper understanding of the material being studied. This study aims to determine the influence and contribution of the problem posing model on the learning outcomes of the human digestive system material of grade 5 SDN Mandurian Hilir. The study conducted experiments related to the problem posing model with a quantitative approach with a quasi-experimental design. The stages of using the problem posing model are: the planning stage, the implementation stage and the reflection stage with 3 descriptive questions. The results of the study found that there was an influence of the use of the problem posing learning model on student learning outcomes in the human digestive system material with a significant value of 0.045. These results indicate that the problem posing model is effective in improving understanding of learning outcomes in the human digestive system material in grade 5.

Microstructural characteristics of hydrogen-exposed P355NH steel and welded joints

It is known that microstructure of materials, such as material structure, grain size, orientation, crystallographic texture and dislocation density, change the mechanism and intensity of hydrogen diffusion, contribute to an increase or decrease in solubility, which significantly changes the mechanical properties of steels and leads to brittleness. In the present study, the microstructure of welded joints of steel P355NH, a typical material grade in domestic transmission lines, and GMAW and hybrid GTAW /GMAW welded joints were investigated and exposed to high pressure pure hydrogen with exposure times of 41 and 92 days. The investigations were carried out to find out the characteristic microstructural details of the base material and welded joints, and the mechanical property changes that can be observed, which can be used to infer the hydrogen susceptibility of both the base material and the welded joints.

Functionally graded material for improved wear resistance manufactured by directed energy deposition

AbstractProtecting components against wear and corrosion is a common way to improve their lifetime. This can be achieved by coating them with a hardfacing material. Common coatings consist of materials such as tungsten carbide or cobalt-chromium alloys, also known as Stellite. Hardfacing materials can be deposited by welding methods like plasma welding or laser cladding. The discrete change of the base material to the hardfacing layer can lead to cracks and chipping. Studies showed a reduced risk of cracking when a functionally graded material is used to create a smooth transition between the base and the hardfacing. Gradings from austenitic steel to cobalt-chromium alloys are already known in the literature. However, there is no knowledge about austenitic- ferritic duplex steels as base material. Therefore, this study aims to demonstrate the feasibility of a functionally graded material from duplex steel to cobalt-chromium alloy with a new approach. By using powder-based directed energy deposition, a graded material with smooth material transition is manufactured additively. Cracking and porosity are examined through metallography. Microhardness measurements as well as the analysis of the chemical composition by energy dispersive X-ray spectroscopy and X-ray fluorescence are used to validate the build-up strategy.

Size-dependent nonlinear dynamics of two-directional functionally graded microbeams in thermal environment under a moving mass

The size-dependent nonlinear dynamics of two-directional functionally graded (2D-FG) microbeams in a thermal environment under a moving mass is studied for the first time in the framework of the refined higher-order shear deformation theory (HSDT) and modified couple stress theory (MCST). The variation of the temperature-dependent material properties in the axial and thickness directions is estimated by the Mori–Tanaka homogenization scheme. Considering the rotary inertia and shear deformation, the nonlinear differential equations of motion, obtained from Hamilton’s principle, are discretized using an enriched beam element. Numerical results determined by the Newmark method in combination with Newton–Raphson iterative procedure confirm the efficiency of the derived beam formulation in predicting the nonlinear dynamics. The enriched beam element, which is derived herein by using hierarchical functions to enrich the conventional shape functions, is capable of furnishing accurate nonlinear dynamic characteristics with fewer elements compared to the conventional one. It is shown that the difference between the dynamic response predicted by the linear analysis and the nonlinear one increases by increasing the temperature, but it decreases by increasing the size scale parameter. The effects of the material gradation, temperature rise and micro-scale parameter on the nonlinear dynamic behavior of the 2D-FG microbeams are studied in detail and highlighted.

Numerical investigation of pre-flawed FGM tubes repaired with different composite jackets under sequential gaseous detonation loading

Investigation on the structural response of pre-flawed functionally graded material (FGM) cylindrical tubes submitted to sequential detonation loading is the main contribution of this study. Analyses are made for repaired and unrepaired tubes using three different composite patch (CP) geometric shapes: full cylindrical, semi-cylindrical, and circular. The effect of non-homogeneous FGM materials (ceramic-to-aluminum, aluminum-to-ceramic, and steel-to-ceramic) and CPs on the stress field in the tube is studied using three-dimensional finite element (FE) models. The FE analyses are conducted for two distinct categories of detonation loading: low- and high-pressure detonations. This approach helps to enhance the understanding of how material gradation influences stress distribution and damage assessment in tubes subjected to these specific loading conditions. The FE analyses revealed that both forward and reflective waves coming from detonation load significantly contribute to crack propagation by elevating stresses near crack tips. The application of CPs, made of boron/epoxy material, effectively mitigated stress concentrations across all FGMs, with full cylindrical CPs providing the best results. Delamination was observed in CPs with two composite layers under high-pressure loading, particularly in aluminum-to-ceramic FGM.

Partially Embedded Metal Rings on the Right Middle Finger and Entrapment of Rings on the Right Index and Ring Fingers in a Psychiatric Patient: A Case Study

Rings are not only commonly worn as symbols of love and commitment, such as wedding rings, but they also serve as decorative pieces in various cultures. The finger rings are made up of materials of different grades (Soft or hard metals), influenced by availability and social customs. However, these accessories can sometimes become problematic when they get stuck on the fingers. This problem tends to occur more frequently in women and younger people. Most of patients present with distal digit swelling and pain, and sometimes present late with gangrene of the involved digits. In most cases, trapped rings do not cause any vascular or neurological damage, but timely removal is critical to prevent complications such as the tourniquet effect, where blood flow to the digit is compromised. The removal of rings is necessary under certain clinical conditions, especially in emergencies where swelling or trauma complicates the situation. Patients with psychological disorders or substance abuse problems may sometimes resist the removal of rings, making treatment more complicated. In this case report, we discuss the management of a psychiatric patient who presented with significant swelling in three digits due to embedded rings, highlighting the delayed treatment and the methods used for successful ring removal. In our case, we managed to remove entrapped and embedded finger rings by non-destructive and destructive methods with good outcomes.

On the behaviour of diagonally-stiffened concrete-filled steel tube-to-SHS steel brace T-joints: An experimental and numerical investigation

In this paper, the behaviour of the T-joint between concrete filled-steel tube (CFST) chord members with diagonal PBL (Perfobond Leiste) stiffeners and square hollow section (SHS) steel braces is investigated. First, seven T-joint specimens were prepared and experimentally tested under axial load of the steel brace. The results were analysed and discussed with respect to the failure modes, load-displacement responses and load-strain curves. Obviously, the diagonal PBL stiffeners were found to effectively limit the cracking range of concrete, thereby improving the bearing capacity of the T-joints. This is followed by a finite element (FE) analysis for the T-joints using ABAQUS software. FE models were validated using the test results and then parametric studies were generated. These studies included the effects of the ratio of brace-to-chord width (β), the ratio of brace-to-chord thickness (τ), the position and thickness of the PBL stiffeners and the steel and confined concrete material grades. Based on the experimental and numerical results, the bending characteristics were obtained for the steel brace-CFST chord T-joint under the axially compressed steel tube brace. Furthermore, the accuracy of the Chinese, Japanese, American and European specifications to calculate the bending bearing capacity of the T-joints were checked, and the results yielded highly conservative results. Therefore, a new calculation method was currently proposed, which takes into account the strengthening effect of the brace on the upper flange of the chord. The comparisons showed that the obtained results of this proposed method are in good agreement with experimental and FE results, and therefore can safely and reliably be used in design.

E-Module for Narrative Texts Oriented Towards Politeness for SD/MI Student

This research aims to develop a politeness-oriented narrative text e-module for SD/MI students. Background to the problem of this research (1) How is the design of a politeness-oriented narrative text e-module for SD/MI students? (2) What are the results of the implementation of the politeness-oriented narrative text e-module for SD/MI students? This research uses research and development methods with the ADDIE (Analysis Design Development Implementation Evaluate) model. The steps of this research consist of needs analysis, designing teaching materials (e-module), developing teaching materials (e-module), product implementation (e-module teaching materials), and product evaluation (e-module teaching materials). Data collection in this research was by collecting data from the results of expert validation questionnaires and student assessment questionnaires. The data obtained was analyzed descriptively using a Likert scale. The results of the validation test by the material expert obtained a score of 3.1, the validation test by the media expert obtained a score of 3.4. The validation test by the Indonesian language teacher obtained a score of 3.75. The results of implementing e-module teaching materials in schools received a positive response from students with a score of 3.35. The conclusion of this research is that the language politeness-oriented narrative text e-module for SD/MI students meets the criteria for being very suitable for use as teaching material by students or teachers in Indonesian language subjects as narrative text material for grade VI SD/MI students.

Study on the Electric Field Distribution Characteristics of 66 kV Dry-Type Transformer Based on Functional Graded Material (FGM) Treatment

Functional graded materials (FGMs) have been successfully applied for improving the insulation performance of insulators, yet there is currently no relevant literature on their application in dry-type transformers. Therefore, it is meaningful to study the feasibility of using FGMs to improve the insulation performance of dry-type transformers through research on electric field distribution. This paper sets FGMs in the dry-type transformer spacer only or both the spacer and winding end to change the relative permittivity values in the corresponding areas. By comparing the electric field distribution characteristics on the inner and outer surfaces of the high-voltage coil and the lower surface of the spacer of the dry-type transformer under each control method with the case without setting FGMs, the study found that when FGMs were only set on the spacer, the control methods set in this paper could not improve the electric field distribution of the transformer. When FGMs are employed at the spacers and end windings, two modulation strategies can mitigate the electric field intensity on the outer surface of the high-voltage windings. Specifically, a continuous increase in relative permittivity can reduce the electric field intensity by 34.02%, while an initial decrease followed by an increase can result in a reduction of 13.58%. This paper provides theoretical guidance for insulation design of transformers with high voltage levels of 66 kV and above, especially as transformers with high voltage levels face greater challenges in regulating surface electric fields.

The influence of bi-directional material gradation on a mode-III crack in functionally graded material via strain gradient elasticity theory

In contrast to classical mechanics, which primarily relies on continuum assumptions and neglects micro-structural effects, the strain gradient elasticity (SGE) theory represents a paradigm shift in understanding the mechanical behavior of materials at small length scales. In this article, the influence of the bi-directional material gradation on a mode-III crack in functionally graded material via SGE theory is studied. The SGE theory uses two material characteristic lengths, ℓ and ℓ′, to account for volumetric and surface strain-gradient factors, respectively. Our investigation is centered on a material gradation model assumed to vary exponentially, with the shear modulus represented as G(x,y)=G0eβx+γy, where β and γ are material gradation constants. To address the crack boundary value problem under consideration, we employ a methodology combining Fourier transforms and an innovative hyper-singular integro-differential equation approach. Using this approach, we systematically formulate a system of equations, which can be solved by selecting suitable collocation points. The closed-form analytical expressions are derived for the standard fracture parameters such as crack surface displacement (CSD), stress intensity factor (SIF), and energy release rate (ERR). Numerical studies are illustrated for the derived standard fractures, and the influence of these parameters β, γ, ℓ, ℓ′, and applied shear load is graphically presented. Through comprehensive analysis, our aim is to provide insights into the complex interplay between material parameters, loading conditions, and crack behavior in functionally graded materials.

Desain Media Pembelajaran Hyperlink Berbasis Canva pada Materi Asmaul Husna Kelas X

This research aims to develop hyperlink-based learning media using Canva application on Asmaul Husna material for grade X students. This learning media is designed as an innovative solution that utilizes interactive features to increase student interest, understanding, and involvement in the learning process. The method used is Research and Development (R&D) with the 4-D development model (Define, Design, Develop, and Disseminate), although in this study only until the development stage. The validation results show that this media is very feasible to use, with a material expert eligibility score of 89.5%, and a media expert of 78.5%. So that the validation results obtained from the hyperlink feature on Canva on class X asmaul husna material can be used as one of the learning media that makes it easier for students to access various additional content such as videos and articles, thus creating a more dynamic and interactive learning experience.

Reliability and Fire Performance of Built-up (Battened) Cold-formed Steel Columns: Numerical study

Cold-formed steel (CFS) columns play a crucial role in modern construction due to their lightweight, prefabricated, and recyclable characteristics, contributing significantly to structural safety and reliability. However, unprotected CFS columns lose their load-bearing capacity within 10-15 minutes under fire conditions. This study reviews recent advancements aimed at improving the fire resistance of CFS columns, focusing on factors such as steel thickness, grade, cross-sectional shape, and fire protection materials. Using ABAQUS software, validated against experimental data, parametric studies reveal that thicker sections and higher-grade steels enhance fire resistance, delaying structural failure. Fire protection strategies, such as plasterboard encasement, further bolster safety. The Complex cross-sectional shape demonstrated the highest load capacity (178.51 kN), while G450 steel outperformed other grades in both load capacity and fire resistance. Columns with 1.95 mm thickness provided the longest failure time (73.49 minutes).

Development of circulatory system mobile learning (CSML) for grade XI students

The utilization of communication devices such as mobile phones as a learning support tool in the development of technology 4.0 is still low. The low mobile phone utilization as a learning support tool causes the variety of learning media used by teachers to be low. The low variety of learning media results in students having difficulty mastering the concept of learning material, especially circulatory system material in class XI. The difficulty of concept mastery on circulatory system material can be overcome through the development of circulatory system mobile learning (CSML). The research objectives are: 1) Develop CSML on circulatory system material in grade XI, 2) Test the feasibility of CSML, and 3) Know the response of teachers and students to CSML. The type of research is Research and Development (R&D) using the ADDIE model (Analysis, Design, Development, Implementation, and Evaluation). Data collection uses feasibility validation questionnaires and response questionnaires. The data analyzed were the results of the feasibility assessment from media experts and material experts, and the results of responses from teachers and students. Data analysis was carried out quantitatively descriptive using a Likert scale of 1-4. The results of the study are 1) The result of developing CSML can be accessed online; 2) The results of the feasibility assessment from media experts were 82.27% and material experts were 89.59% with a very feasible category; 3) The results of teacher responses were 87.02% and student responses were 88.55% with a great category.