Waluyo Adi Siswanto

Axial Impact Performance of Aluminium Thin Cylindrical Tube

One of the important objectives in this research is investigating the behavior on the cylindrical tube structure via computer simulations. When a thin cylindrical structure is experienced an impact loading, the crushing process on impact can only be observed by a high speed camera. Recording the stress and strain data is also not possible experimentally. A numerical approach implementing finite element method with a dynamic-explicit code is an effective solution to observe the crushing process. A thin cylindrical structure found in aluminium can is modeled. A finite element impact simulation is then performed to observe the crushing process sequence and the stress and strain development history on axial impact employing IMPACT application program. An experimental of thin cylindrical structure on axial impact is conducted. The final crushing pattern after the impact is then compared with that from simulation. The result shows that final crushing pattern is in a good agreement with that shown in experiment. The stress and strain histories can be observed from the simulation.

A Platform for Digital Reproduction Sound of Traditional Musical Instrument Kompang

This work proposes a system for the digital reproduction sound of kompang. The kompang sounds are represented by bung and pak produced by palm beating to the membrane. The sounds are recorded in an acoustical sound recording system. In this proposed system, the recorded sounds are then analyzed in a frequency analyzer SpectraPLUS. This frequency contents data can be used as the reference to check the reproduced digital sound. The recorded wave data is converted to MIDI format before being manipulated in Ableton synthesizer system to create modern keyboard notes but representing kompang sound. For the validation purpose, a subjective approach as an additional to the objective comparison with frequency contents is also proposed.

The Influence of Plasma Nitrocarburizing Process Temperature to Commercially Pure Titanium Surface Hardness

Commercially pure (cp) titanium is a relative soft metal and easily broken on friction-wear applications. To improve the hardness of the surface while maintaining the original properties, plasma nitrocarburizing process has been conducted. The effects of the treatment in different temperatures to the surface harness are then studied. In this study, cp titanium plasma nitrocarburizing process is conducted at different temperatures with different process time, i.e. at 350 °C for 3, 4, and 5 hours, and at 450 °C for 2, 3, and 4 hours respectively. Hardness tests are then performed on each specimen by using Micro Vickers Hardness Tester. The hardness values for the plasma specimens nitrocarburizing processes at temperature of 350 °C for process duration of 3 hours, 4 hours, and 5 hours are 74.16 HV, 92.25 HV and 94.41 HV, respectively, while for processes at temperature of 450 °C, the hardness values are 103.70 HV, 121.31 HV, and 126.17 HV for process duration of 2 hours, 3 hours, and 4 hours respectively. Hardness value of specimens which are resulted from the plasma nitrocarburizing process at temperature of 450 °C is higher compared with specimens that are processed at temperature of 350 °C.

The Use of Abaqus for Teaching the Development of Cavity Defects in Forward Extrusion Processes

Cavity defects occur in extruded products, especially in a relatively short, headed product when the remaining billet reaches a certain thickness. Such defects can be a serious problem in manufacturing because they produce waste material and require an extra operation for finishing. Therefore an understanding of the process of cavity formation is important. A virtual simulation of the development of the defect facilitates student understanding. This paper introduces a detailed explanation of cavity formation that uses a non-linear finite element method package, Abaqus. The simulation result shows the shape conditions during the extrusion process.

Investigation on the Effect of Linear Kinematic Hardening Model on Plasticity Prediction of Reciprocating Sliding Contact

This paper discusses a finite element analysis of cylinder on flat contact configuration subjected to constant normal load and reciprocating tangential displacement with linear kinematic hardening models based on bi-modal Ti-6Al-4V cyclic stress-strain curves. The predicted evolution of plastic deformation such as the equivalent plastic strain, tangential plastic strain and shear plastic strain distributions on the contact region has been studied along with its respective predicted stress distributions. The effect of applied forward and backward sliding displacement movements on predicted stress and strain distributions have also been looked at. It is found that the stress distributions predicted for kinematic hardening model is similar for forward and backward movements while the predicted plastic strain distribution is increasing with reciprocating sliding movement. The predicted value keep increasing when it moves forward, backward and finally moves forward again. This is due to large strain effect of the model and its dependant on the displacement movement amount.

An Alternate Method to Springback Compensation for Sheet Metal Forming

The aim of this work is to improve the accuracy of cold stamping product by accommodating springback. This is a numerical approach to improve the accuracy of springback analysis and die compensation process combining the displacement adjustment (DA) method and the spring forward (SF) algorithm. This alternate hybrid method (HM) is conducted by firstly employing DA method followed by the SF method instead of either DA or SF method individually. The springback shape and the target part are used to optimize the die surfaces compensating springback. The hybrid method (HM) algorithm has been coded in Fortran and tested in two- and three-dimensional models. By implementing the HM, the springback error can be decreased and the dimensional deviation falls in the predefined tolerance range.

Numerical Study on Failure Process of Aluminium Plate Subjected to Normal Impact by Hemispherical Projectiles

In this paper a study is presented on the numerical analysis of the failure process of aluminium armour plate subjected to normal impact by hemispherical projectiles. The perforation process has been simulated by the application of 3D analysis using IMPACT dynamic FE program suite. The comparison on the elements size of meshing towards failure mode was observed and evaluated. The material behaviour of the target plate was approximated by an appropriate constitutive relation. The study covered different size of meshing element on target plate as well as different level of impact velocities. Different failure modes for each case were found. For low speed impact condition a petalling was observed, whereas for high speed impact a radial neck along with a holes enlargement was observed with better and uniform perforation mode. The deformation and failure mode of the impacted target plate will be given special attention in this investigation.

Computational Issues in the Simulation of High Speed Ballistic Impact: A Review

This paper presents a review of recent developments of nonlinear constitutive material models for the applications in high speed ballistic impact of projectile into several types of targets. The objective is to comprehend some numerical approaches that have been proposed and used in the technical literatures especially regarding bullet-target interaction. Attention is given on the application of several types of computational constitutive models and simulations used to represent the projectile characteristic, ballistic penetration, failure modes in target and deformation pattern. This paper serves as a concise source to identify future direction in the area of computational mechanics of high speed collisions and provides brief literatures for those interested in conducting research into the topic.

Simulation of Ironing Process for Earring Reduction in Sheet Metal Forming

Manufacturing of beverage cans is porcessed by using multi-stage ironing following deep drawing from the sheet material of aluminum and steel. An earing profiles are develops during deep drawing of cylindrical cup due to the planar anisotropic properties of sheet. Therefore, the analysis of earing is important to evaluate and control the development of earing. This paper describes a simulation of the cold ironing process in the forming cylinder cap. The ironing process in this study was focused on the prediction of height increasing, earing and thinning. Two different materials of aluminum AA5042 and AKDQ steel were selected for comparison. The results show that the increasing of cup height was in the same trend.

Shaker table design for electronic device vibration test system

A general purpose vibration test system has been developed to provide a testing platform for electronic devices. This paper presents the design of the shaker table for the platform-testing base where an electronic device will be placed and excited by the vibration exciter. Three design models are first analyzed their natural frequencies and the corresponding mode shapes. The model with the lightest weight and the highest first natural frequency is then selected to be manufactured. This selected shaker stable can be used in a frequency range of service up to 2500 Hz and behaves as a rigid body when it vibrates. The maximum dimension of the electronic device that can be placed in the shaker table is 15 cm square. This paper also provides the general frequency range limitation when the vibration test is used at constant displacement or constant acceleration test. The suggested frequency ranges satisfy all limitation requirements of the shaker.