Samsul Rizal

The dynamic properties behavior of high strength concrete under different strain rate

This paper present a number experimental data and numerical technique used in the dynamic behavior of high strength concrete. A testing device is presented for the experimental study of dynamic behavior material under high strain rates. The specimen is loaded by means of a high carbon steel Hopkinson pressure bar (40 mm diameter, 3000 mm long input bar and 1500 mm long out put bar) allowing for the testing of specimen diameter is large enough in relation to the size of aggregates. The other method also proposed for measuring tensile strength, the measurement method based on the superposition and concentration of tensile stress wave reflected both from the free-free ends of striking bar and the specimen bar. The compression Hopkinson bar test, the impact tensile test of high strength concrete bars are performed, together with compression static strength test. In addition, the relation between break position under finite element simulation and impact tensile strength are examined. The three-dimensional simulation of the specimen under transient loading are presented and comparisons between the experimental and numerical simulation on strain rate effects of constitutive law use in experimental are study.

Fundamental Study on the Carbonization Characteristics of Low Rank Coal Under Low Temperature and its Application on Traditional Blacksmith

The fundamental study on carbonization characteristic of low rank coal under low temperature was investigated by using a laboratorium scale electric furnace. In this experiment, the mass decreasing fraction of coal during carbonization, the bahaviour of volatile matter and the changes of fixed carbon as well as gas composition during carbonization was carried out. The effect of fixed carbon content in fuel on iron quality is also investigated. The experimental method for investigation of low rank coal carbonization characteristic was selected by variation of the carbonization temperature and nitrogen was introduced as a carrier gas. The experimental result shows that the mass decreasing fraction of coke was increased with the carbonization period. The fixed carbon content in coke was increased with the carbonization temperature. The gas composition during carbonisation shows consist of argon (Ar), carbon monoxide (CO) and methane (CH4). It shows that the CO gas is dominated of the amoung them. It is shown that the iron surface hardness may affect on carburizing media.

Effects of strain rate on failure mechanisms and energy absorption in polymer composites

Abstract This chapter discusses the effects of strain rate on failure mechanisms and energy absorption in polymer composites. This chapter starts by introducing the definition of energy absorption, failure mechanisms as well as strain rate. The methods commonly used to determine the effects of the strain rate in polymer composites are also explained. By the end of the chapter, an outline of the main results on the effects of strain rate on failure mechanisms and energy absorption in various types of polymer composites, such as synthetic fiber-reinforced thermoplastic/thermoset composites, natural fiber-reinforced thermoplastic/thermoset composites as well as thermoplastic/thermoset-based hybrid composites are presented.

Beeswax as phase change material to improve solar panel’s performance

One of the main obstacles faced during the operation of photovoltaic (PV) panels was overheating due to excessive solar radiation and high ambient temperatures. In this research, investigates the use of beeswax phase change materials (PCM) to maintain the temperature of the panels close to ambient. Solar panels used in this study has 839 mm length, 537 mm wide, and 50 mm thick, with maximum output power at 50 W. During the study, there were two solar panels was evaluated, one without phase change material while the other one was using beeswax phase change material. Solar panels were mounted at 15° slope. Variables observed was the temperature of solar panels surface, output voltage and current that produced by PV panels, wind speed around solar panels, and solar radiation. The observation was started at 07:00 am and ended at 06:00 pm. The research shows that maximum temperature of solar panels surface without phase change material is ranging between 46-49 °C, and electrical efficiency is about 7.2-8.8%. Meanwhile, for solar panels with beeswax phase change material, the maximum temperature solar panels surface is relatively low ranging between 33-34 °C, and its electrical efficiency seems to increase about 9.1-9.3%.

Biodegradable Films for Fruits and Vegetables Packaging Application: Preparation and Properties

Fresh-cut fruits and vegetables are highly perishable commodities. Packaging forms an important tool to maintain the shelf life of packed fresh-cut agricultural produce. Petroleum-based films are conventionally used for fresh fruits and vegetables. However, being nonbiodegradable and derivability from nonrenewable resources, these films lead towards serious ecological problems. To address this issue, various efforts have been focused on renewable and biodegradable films obtained from biopolymers. Widely studied biopolymers for film preparation are derived from biomass (gelatin, starch, cellulose, etc.), microbes (polyhydroxyalkanoates), and bio-derived monomers (polylactic acid). However, such films possess poor mechanical and barrier properties as compared to their commercial counterparts. Incorporation of various additives has been proposed to improve the film characteristics. In the present review, comprehensive information has been provided on different methodologies for film fabrication, properties, and applications of stand-alone bio-based films for packaging of fresh-cut produce. Furthermore, successful commercial implementation of such film is also summarized.

Preparation and Characterization of Microcrystalline Cellulose from Sacred Bali Bamboo as Reinforcing Filler in Seaweed-based Composite Film

Microcrystalline cellulose (MCC) isolated from cheap, fast-growing and abundant accessible Sacred Bali bamboo (Schizostachyum brachycladum) was utilized as reinforcement material in the seaweed-based composite film. Isolation of MCC was carried out by using a combination of pulping, bleaching and acid hydrolysis process. This study emphasized on the feasibility of MCC production from Sacred Bali bamboo by studying its properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The commercial-MCC (CMCC) was used as reference material. Results showed that the production yield, moisture content (MC) and fiber length of bamboo-MCC (BMCC) were 83.37±1.48 %, 4.50±0.5 %, and 0.47±0.02 mm, respectively. According to the chemical analysis by FTIR, both lignin and hemicellulose were completely removed from BMCC, and thus, improved the crystallinity (78 %) and thermal stability (≈325 °C) of BMCC. This study also revealed that MCC produced from Sacred Bali bamboo demonstrated strong mechanical reinforcement effect in the seaweed-based film. Hence, Sacred Bali bamboo-MCC could be used as reinforcement material in the polymer.

Role of Universities in Disaster Management and Recovery from the Indian Ocean Tsunami: Perspective from Aceh, Indonesia

The Province of Aceh, Indonesia, was massively devastated by the 2004 Indian Ocean tsunami on an unimaginable scale for most of the Acehnese people. This mega-disaster caused an enormous number of human casualties, ruined almost all critical sectors, and paralyzed many government functions. Such an extreme disaster was the worst ever experienced by Aceh, and there was a severe lack of knowledge on how to manage the aftermath of the disaster. Although the Syiah Kuala University, the largest public university in Banda Aceh (the capital of Aceh Province), was severely affected, it played a crucial role in the recovery process and is still continuing the same, particularly in building disaster-related knowledge and dissemination capacity in the region. This paper presents an overview of two main issues: (1) to describe general conditions in Aceh before the tsunami, damages caused by the tsunami, and Syiah Kuala University’s involvement in post-tsunami recovery and disaster risk reduction (DRR) activities and (2) to share our perspective and consideration of the role of disaster-affected universities (universities located in disaster-prone areas) in the anticipation of future disasters. We firmly believe that one important role of the university is to accumulate disaster knowledge and conduct education on DRR. Through such activities, the university can promote and help develop DRR in the communities. Therefore, universities located in disaster-prone areas should put significant efforts into building their knowledge capacity, and collaborations and knowledge sharing among these universities should be encouraged.

Influences of strain rate on yield strength aluminum alloys

The simulation of aircraft has often been performing by implementing finite element code on supercomputers. The reliability an accuracy of simulation depends mainly on the material model as well as on structural model used in calculations. Consequently, an accurate knowledge of mechanical behavior of materials under impact loading is essential for safety performance evaluation of structure. Impact tension tests on specimens for aircrafts and automotive structural applications are conduct by means of the split Hopkinson bar apparatus. Small specimens having diameter 4 mm are use in the test. Tensile stress-strain relations at strain rates of 102 s-1 to over 103 s-1 are present and compared with those obtained at quasi-static strain rates. The limitations on the applicability of apparatus are also discusses. The other importance of the reference of strain, while studying void growth in elastic-viscoplastic material, is emphasized. In the present paper, a simplified plane-symmetrical two-dimensional finite element model for a SHPB with a plate specimen made of an elastic material is first established. The used of strain gage mounted at the specimens to be monitored strain during the course of impact test. Comparisons may then be made between the numerical predicted and experimentally observed of load and a specimen strain. This report also describes the apparatus and instrumentation, and also be discusses the advantages and limitations of experimental technique. Fractograph is taken by scanning electron microscope on the center of the specimens for judgment of the fracture mechanism and strain rates influences on the materials.