Heru Santoso Budi Rochardjo

Preliminary Investigation on Bulletproof Panels Made from Ramie Fiber Reinforced Composites for NIJ Level II, IIA, and IV:

Ramie (Boehmeria nivea) is one of the strongest natural cellulose fibers. Optimizing abundant resources ramie as a candidate materials used for reinforcing in polymeric composite material is a must to obtained high-performance natural fibers reinforced polymer especially for bulletproof panel or high-impact flexibility safer structures. Ramie woven was treated using common chemical solvents that were ethanol, methyl ethyl ketone, acetone, and silane as coupling agent. Composite panels were made by hand lay-up process with epoxy as a matrix. These prototype bulletproof panels were to be believed lighter in weight and much lower economic cost than conventional bulletproof panels made from ceramic plate, Kevlar/aramid composite, and steel-based material as a popular today in military standard antiballistic equipments. From the bullet testing result, it showed that panel could be able to resist the penetration of high-impact projectile for level II with some fractures phenomenon. Level IV ballistic testing showed that all prototype panel could not resist the high-impact velocity of the projectile yet. It was found that ramie fibers have sufficient breaking strength and toughness for level II bullet testing, although still needs improvements to optimize process parameters to meet a very high military standard and application

Identification of Ramie Single Fiber Surface Topography Influenced by Solvent-Based Treatment

The effects of alcohol, acetone, and methyl ethyl ketone solvent-based treatment on surface topography of ramie single fiber are investigated. In this study, the average of specific porous volume and specific surface area of ramie single fiber are determined to interpret the effects of the treatment quantitatively using Brunauer-Emmet-Teller surface area method. Fourier Transform Infrared Spectroscopy is applied directly to the fiber to detect the differences of molecular group function in the fiber surface. Qualitatively, scanning electron microscopy was also provided. The result shows that the solvent treatment could improve surface topography to gain matrix penetration when utilizing the fiber into polymeric composite material.

The prediction of energy-absorption on the car crush box

This paper describes a computationally aided design process of a thin-walled structure of a retail car crash box subjected to a progressive crashing in longitudinal axial direction. The study was broken up into three phases: (1) digitising of the existing retail car crash box structure, (2) the crash simulation of the structure using dynamic explicit formulation (3) the verification of the simulation of the accident. In the digitalization phase of this structure, the perimeter of the cross section, the shape, the length and the thickness of profile were made the same as the Original Equipment Manufacturer (OEM) the product of a compact car found in the local market. The crashing procedure and parameter follow the New Car Assessment Program (NCAP) by National Highway Traffic Safety Administration (NHTSA). It found that the value of energy absorbed by the crash box was 5.91 KJ. The specific energy absorption is 21.53 KJ/kg. The crash force efficiency is 0.54. The simulation method, that was verified using square tube structure, resulting in the value that matches to the current simulation done by another researcher.

Effect of sonication treatment on fibrilating snake fruit (Sallaca) frond fiber

Aim of this research is to investigate influence of chemical and sonication treatment on fibrillating and mechanical properties of snake fruit frond fiber. The presence of surface impurities and the large amount of hydroxyl groups in natural fibers make less attractive for polymeric materials reinforcement. Effort to remove the impurities can be done by few treatments that consist of physical, chemical and mechanical treatment. Snake fruit frond bundle fiber were firstly subjected to chemical treatments with alkali solution, steaming at 2 bar and steam explosion at 6 bar by 40 times releasing of steam. Advanced treatment is done by flowing ultrasonic wave at 20 kHz by 90 – 210 watt. The output of fibrillation can reach fiber in range 10 – 25 nm compared with 10.72 µm in diameter for sonication and 6 bar in pressure of steam with 40x of rapidly steam release respectively.

Effects of alkali and steaming on mechanical properties of snake fruit (Salacca) fiber

The aim of this research is to investigate the effect of alkali treatment and steaming on mechanical properties of Snake Fruit frond fiber. The presence of surface impurities and a lot of hydroxyl groups makes natural fiber less compatible for composite materials reinforcement. Efforts to remove the impurities can be done by physical, chemical and mechanical treatments. This paper reports the treatment of Snake Fruit frond single fiber by subjecting it to alkali treatments with 2%- 8% NaOH for 2 - 6 hours at room temperature. The treatment is then followed by steaming at a pressure of 2 bars in 1 hour. Results show that the treatment of alkali and the alkali-steaming combination can increase cellulose percentage. The tensile tests show that this type of treatment in combination resulted in the higher tensile strength compared to untreated fiber. There is a significant increase in tensile strength with increasing alkali percentage. However, the further increase in the percentage of alkali solution will res...

Development of styrofoam cutter NC machine for intricate cutting path

This paper deals with the design, manufacture and application of NC machine for cutting 2D intricate path of plane styrofoam. The cutter uses nickel wire heated by DC electric current. The X and Y axis is moved using open loop controlled stepper motor. The path that is cut is first was taken from picture, than changed the captured picture into line graph, and then programming the machine to follow the resulted line. The result shows that the machine can cut well in intricate path shape in the form of wayang figure without typing manually long NC code. The testing shows that the average distance error reaches of 0,245 mm on average in both x and y axis.

The crushing behaviour of bamboo — Epoxy composite tube

An experimental investigation was conducted to study the crush-worthiness parameters and behaviour of the bamboo-epoxy composite tube with chamfering angle 45° at one end. Quasi-static compressive loadings were applied axially to investigate the response of force-displacement during progressive collapses. The Shimadzu concrete compression testing machine with capacity 2000 KN was used in this experiment. Load-displacement curve and collapses mode of the specimen are presented and discussed. The results showed that this novel uni-directional bamboo-fibers/epoxy tube could absorb 5.01 KJ energy caused by moving of cross head as far as 50 mm. The other crush-worthiness parameters are force average, crush force efficiency, and the specific energy absorption which have value of 102.60 KN, 0.57, and 18.23 KJ/kg, respectively. The progressive collapse mechanisms which occur in this experimental design are consisting of fragmentation and splaying failure modes. In conclusion, the results demonstrate a novel Crash box product constructed from bamboo and epoxy with good performance findings within crash-worthiness parameters comparing to the original equipment manufacturer product.