Wahyudin Syam - Academia.edu (original) (raw)

Papers by Wahyudin Syam

Scientific Reports, Aug 8, 2019

Recent advances in additive manufacturing have enabled fabrication of phononic crystals and metam... more Recent advances in additive manufacturing have enabled fabrication of phononic crystals and metamaterials which exhibit spectral gaps, or stopbands, in which the propagation of elastic waves is prohibited by Bragg scattering or local resonance effects. Due to the high level of design freedom available to additive manufacturing, the propagation properties of the elastic waves in metamaterials are tunable through design of the periodic cell. in this paper, we outline a new design approach for metamaterials incorporating internal resonators, and provide numerical and experimental evidence that the stopband exists over the irreducible Brillouin zone of the unit cell of the metamaterial (i.e. is a three-dimensional stopband). the targeted stopband covers a much lower frequency range than what can be realised through Bragg scattering alone. Metamaterials have the ability to provide (a) lower frequency stopbands than Bragg-type phononic crystals within the same design volume, and/or (b) comparable stopband frequencies with reduced unit cell dimensions. We also demonstrate that the stopband frequency range of the metamaterial can be tuned through modification of the metamaterial design. Applications for such metamaterials include aerospace and transport components, as well as precision engineering components such as vibration-suppressing platforms, supports for rotary components, machine tool mounts and metrology frames. Phononic crystals (PCs) are engineered materials designed to control elastic wave propagation. PCs generally rely on high impedance mismatches within their structural periodicity to form Bragg-type stopbands that exist due to the destructive interference between transmitted and reflected waves. The presence of destructive interference prevents specific wave types from propagating. Kushwaha et al. 1 presented the first comprehensive calculation of acoustic bands in a structure of periodic solids embedded in an elastic background. James et al. 2 used a periodic array of polymer plates submerged in water and provided experimental realisation of one-dimensional (1D) and two-dimensional (2D) PCs. Montero de Espinosa et al. 3 used aluminium alloy plates with cylindrical holes filled with mercury to generate 2D ultrasonic stopbands. Tanaka et al. 4 studied the homogeneity of PCs in the perpendicular direction to the direction of propogation, and classified PCs into bulk PCs and slab PCs. Research on the design, manufacturing and testing of PCs has mainly focused on 1D and 2D PCs 5-15 , although recently, the research has been extended to include 3D PCs 16-24. Lucklum et al. 25 discussed the manufacturing challenges of 3D PCs and showed that additive manufacturing (AM) has the fabrication capabilities required for the realisation of geometrically complex 3D PCs 26-29. There are a wide variety of AM technologies that may be used to manufacture PC materials, such as laser powder bed fusion (LPBF), photo-polymerization, stereolithography and inkjet printing 30-33. Although differing in the manufacturing resolution (the thickness of the build layer), materials, design constraints and cost, these AM technologies create 3D parts from a CAD model. The creation of the 3D parts is usually carried out layer by layer, and the thickness of the deposited layers, as well as the effects of post-processing, determine the geometrical quality of the created 3D parts 34,35. Despite the benefits of the recent ability to manufacture PCs with AM, their effectiveness at low-frequencies is limited due to the dependency of the resulting stopbands on Bragg scattering. Bragg scattering occurs due to destructive interference of the propagating waves with the in-phase reflected waves, which occurs when the wavelengths of the reflected and propagating waves are similar. The reflection occurs due to the difference in the

Virtual and Physical Prototyping, Jun 1, 2011

... View larger version(56K), Figure 11. (a) 3D volume rendered of CT scan of a 25-million year o... more ... View larger version(56K), Figure 11. (a) 3D volume rendered of CT scan of a 25-million year old juvenile Diprotodontid silvabestus skull, (b) Biomodel of Diprotodontid Silvabestus (D'urso et al. 200012. D'urso, PS, Thompson, RG and Earwaker, WJ 2000. ...

IEEE/ASME Transactions on Mechatronics

Procedia CIRP, 2018

In the last decade, there has been considerable growth in the production of end-use polymer parts... more In the last decade, there has been considerable growth in the production of end-use polymer parts and components using additive manufacturing methods. A wide range of polymers, from Nylon-12 to thermoplastic polyurethane polymers, can be processed with complex geometry tailored to specific function. However, due to the nature of the layer-by-layer process used in additive manufacturing, high roughness surfaces remain on the parts. To reduce the roughness of the surfaces, a proprietary post-processing method, developed by Additive Manufacturing Technologies, is applied to the surfaces. To monitor and control the finishing of the surfaces, an in-process surface detection instrument has been developed based on machine vision and machine learning. This paper presents the machine learning approach and the effectiveness of the instrument for in-process measurement of the finished surfaces.

Proceedings of the 54th Annual Precise Time and Time Interval Systems and Applications Meeting

The version presented here may differ from the published version or from the version of record. I... more The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.

Proceedings of the 2023 International Technical Meeting of The Institute of Navigation

Physics Education, 2021

Light spectrum dispersion is an exciting subjectin science because of its beautiful atmospheric c... more Light spectrum dispersion is an exciting subjectin science because of its beautiful atmospheric colour phenomenon which attracts students. However, to see the phenomenon is not easy since it needs a spectrometer, which is commonly expensive. Therefore, the present study aims to describe a low-cost spectrometer for investigating lighting spectrum and analysing the purity of honey as a pedagogical students’ project. The spectrometer was constructed from a webcam connected to a laptop, a free spectrometer software, DVD disk, and black cardboard. The calibration of the developed spectrometer used an Argon (Ar) lamp. Afterwards, measurement tests were carried out by using Neon (Ne) and Xenon (Xe) lamps. A white light-emitting diode was used as a light source to measure several types of honey wavelengths. The results from the experiment show that the wavelength of Ar, Ne, and Xe are (503 ± 4) nm, (463 ± 3) nm, and (451 ± 3) nm respectively. The measurement accuracy of the spectrometer is ...

Optical instruments for areal topography measurement can be especially sensitive to noise when sc... more Optical instruments for areal topography measurement can be especially sensitive to noise when scanning is required. Such noise has different sources, including those internally generated and external sources from the environment [1].For some instruments, it is not always possible to evaluate each single contributor. Nevertheless, it is possible to evaluate the noise added to the output during the normal use of the instrument. Such noise is defined in ISO 25178 part 605 [1] as “measurement noise”. In this work, the measurement noise is assessed for a commercial point autofocus instrument (Mitaka MLP-3SP), installed in the manufacturing metrology laboratory at The University of Nottingham. The investigation is carried out by areal acquisitions of 100µm×100µmwith a100×magnification objective and a sampling distance of 0.1µm along the x-axis and 1µm along the y-axis. The measurement noise is evaluated by applying established subtraction and averaging methods described elsewhere [2,3]. ...

Measurement Science Review

The paper presents the comparison of uncertainty measurement estimations of the energy performanc... more The paper presents the comparison of uncertainty measurement estimations of the energy performances of gas stoves. The Guide to the Expression of Uncertainty in Measurement (GUM) framework and two Monte Carlo Simulation (MCM) approaches: ordinary and adaptive MCM were applied for the energy performance uncertainty: thermal energy and efficiency measurement uncertainties. The validation of the two MCMs is performed by comparing the MCM estimations to the GUM estimations for the thermal energy and efficiency measurement results. A test method designed in Indonesia National Standard SNI 7368:2011 was employed for the thermal energy and efficiency determinations. The results of the GUM and two MCM methods are in good agreement for the estimation of the thermal energy value. Significant differences of the uncertainty estimations for the thermal energy and efficiency results are observed for both GUM and MCM methods. Both the ordinary and adaptive MCM estimations give larger coverage inte...

Rapid Prototyping Journal, 2012

PurposeThe purpose of this paper is to investigate the potential application of electron beam mel... more PurposeThe purpose of this paper is to investigate the potential application of electron beam melting, as a layered manufacturing process, to fabricate dental coping of metal‐ceramic crown restoration using Ti6Al4V powder.Design/methodology/approachThis experiment was conducted in two steps: shrinkage study to determine scale up factor for shrinkage compensation and parameter selection study, based on thickness, hardness, and surface roughness, to select process parameter of electron beam melting.FindingsA promising result of fabricating metal coping of Ti6Al4V via electron beam melting was shown. Ti6Al4V coping was successfully fabricated, with an average thickness of 0.52 mm required for dental coping. Total average hardness of 333.35 HV that is comparable to casted Ti6Al4V with considerably high roughness of RSm of 382 μm.Originality/valueThe paper presents a novel application of electron beam melting to fabricate metal coping for metal‐ceramic crown restoration.

Applied Soft Computing, 2013

In this study, we addressed Single Objective Linear Programming (SOLP). This article proposed a n... more In this study, we addressed Single Objective Linear Programming (SOLP). This article proposed a new combination of Chaos Optimization Algorithm (COA) with Affine Scaling Search (AFS) to be used as a Hybrid COA and AFS algorithm (Chaos AFS) for solving SOLP. The potential of COA as an emerging optimization algorithm to improve efficiency and effectiveness of AFS is investigated. Chaos AFS method is so-called numerical search algorithm that searches through the domain of decision variables of SOLP to obtain final feasible solution. An initial solution point, obtained from COA, will be used as starting solution point in AFS algorithm to improve the performance of AFS algorithm. The result shows that Hybrid COA and AFS for solving SOLP problems significantly improves the results of objective value compared to pure AFS and reduces the number of iteration steps compared to simplex and pure AFS.

Procedia CIRP, 2014

Additive manufacturing (AM) is becoming more diffused. In spite of its advantages: capability to ... more Additive manufacturing (AM) is becoming more diffused. In spite of its advantages: capability to manufacture complex internal feature and material efficiency, AM has inherent drawback from its layer-by-layer nature. "Staircase effect" is observed due to the slicing process of the computer model in which a rough surface from a theoretically smooth surface will be obtained. Hence, there will be a deviation of the produced part from its nominal model. A methodology to predict the deviation of computer model of an additive manufactured part after fabrication process is presented. A case study is proposed using cylindrical features due to its common real case application. Cylinder is a representation of pin-hole geometry. This geometry is an assembly feature which is very important to guarantee the parts can be assembled with their pair. The dimensional and geometric deviation of the cylindrical feature after fabrication is estimated and could be a useful information for the designer.

Measurement Science and Technology, 2014

In some applications of CSI, the user’s understanding of the operating principles of the instrume... more In some applications of CSI, the user’s understanding of the operating principles of the instrument can be low – technicians who are not specialised metrologists will often use the instrument as a “black box”. As with all metrology instruments, CSIs can be sensitive to changes in measurement conditions. With the increase in interest in surfaces controlled to nanometric tolerances, the potential for unknown effects is likely to become an increasingly serious issue for the CSI users.

Highly miniaturized systems find applications in key technological fields such as health-care, mo... more Highly miniaturized systems find applications in key technological fields such as health-care, mobility, communications and optics. Required innovations for precision manufacturing of micro components can be achieved through post-process and in-process measurement of process input and output parameters. Hence, it is of critical importance to reduce the measurement and optimization effort, since process and product quality control can take a significant part of the production time in micro manufacturing. To solve this challenge, research is undertaken in order to define, investigate, implement and validate the “Product/Process Micro Manufacturing Fingerprint” concept. In particular, in the Horizon2020 Innovative Training Network “Process Fingerprint for Zero-defect Net-shape MICROMANufacturing”, 9 beneficiaries and 14 industrial partners are collaborating to establish this concept for several manufacturing technologies, such as micro injection and micro ultrasonic moulding, micro mec...

Information-rich metrology (IRM) is a new term that refers to an approach, where the conventional... more Information-rich metrology (IRM) is a new term that refers to an approach, where the conventional paradigm of measurement is transcended, thanks to the introduction and active role of multiple novel sources of information. The overarching goal of IRM is to encompass and homogenise all those measurement scenarios where information available from heterogeneous sources, for example, from the object being measured, the manufacturing process that was used to fabricate it, the workings of the measurement instrument itself, as well as from any previous measurements carried with any other instrument, is gathered and somewhat incorporated with an active role into the measurement pipeline in order to ultimately achieve a higher-quality measurement result (better metrological performance, shorter measurement times, smaller consumption of resources). Examples of IRM in action in precision and additive manufacturing will be presented, including the measurement of form and texture.