Wibowo Wibowo

Bio: Wibowo Wibowo is an academic researcher from Sebelas Maret University. The author has contributed to research in topics: Physics & Magnetorheological fluid. The author has an hindex of 2, co-authored 15 publications receiving 14 citations.

Tinjauan kuat tekan dan modulus elastisitas beton dengan menggunakan limbah batu candi sebagai pengganti agregat kasar

Abstract: Nowadays the use of concrete is increasing but the concrete raw materials fulfillment is decreasing. In this case, one of alternative is to be replacedthe coarse aggregate with lava stone waste obtained from the production residue of natural stone craftsmen in Sambirejo, Prambanan,Yogyakarta.The purpose of this research was to determine the concrete compressive strength, modulus of elasticity of concrete with lava stone wasteas substitute for coarse aggregate, and determine the maximum ratio of lava stone waste as the coarse aggregate in terms of compressive strength andmodulus of elasticity appropriate quality targeted.The method used in this research is the experimental method. Samples form is made as cylinder with 15 cm of diameter and 30 cm of high.Targeted quality of concrete is 25 MPa with lava stone percentage levels of 0%, 20%, 40%, 60%, 80%, 100% replaces the coarse aggregate.The compressive strength of concrete decreased at comparable levels with the addition of lava stone as the coarse aggregate. Value of the averagecompressive strength of concrete at 28 days was 36,768 MPa (lava stone 0%); 31,300 MPa (lava stone 20%); 28,283 MPa (lava stone 40%);27,152 MPa (lava stone 60%); 25,266 MPa (lava stone 80%); and 24,135 MPa (lava stone 100%). Modulus of elasticity was also decreasedlevels comparable to the addition of the lava stone. Average modulus of elasticity value is 22818,000 MPa (lava stone 0%), 18832,333 MPa(lava stone 20%), 16462,333 MPa (lava stone 40%), 15870,667 MPa (lava stone 60%), 15098,000 MPa (lava stone 80%), and13933,333 MPa (lava stone 100%). Concrete qualified targeted quality is lava stone concrete with the maximum level to 80% with averagecompressive strength is 25,266 MPa.

A mathematical modelling and experimental study of annular-radial type magnetorheological damper

Abstract: An experimental study was undertaken to evaluate the mathematical modelling of the magnetorheological (MR) damper featuring annular radial gap on its valve. The experiment was conducted using a fatigue dynamic test machine under particular excitation frequency and amplitude to get force-velocity and force-displament characteristics. Meanwhile, the mathematical modelling was done using quasi-steady modelling approach. Simulation using adaptive neuro fuzzy inference (ANFIS) Algorithm (Gaussian and Generalized Bell) were also carried out to portray the damping force-displacement modelling that is used to compare with the experimental results. The experimental characteristics show that amplitudes excitation and current input affect the result damping force value. The comparison of the experimental and mathematical results presented in this paper shows a significant difference in damping force value and that the quasi-steady modelling could not significantly approach the damping force-velocity results. Moreover, the semi-active damper is compared to the passive damper. The results show that a semi-active damper performs better than a passive damper because it only requires a little power. Based on the damping force-displacement modelling, it can be seen that Gaussian has a higher accuracy rather than Generalized Bell. Discussion on the energy dissipation and equivalent damping coefficient were also accomodated in this paper. Having completed in mathematical modelling and simulation, the damper would be ready for further work in-vehicle application that is development of control system.

Evaluasi kinerja struktur gedung bertingkat dengan analisis riwayat waktu terhadap drift dan displacement menggunakan software etabs (studi kasus : hotel di daerah karanganyar)

Abstract: Indonesia lies between severally tektonik's plate universalizes, which is Australian Eurasian plate one moves to aim northern, moving Pacific plateto aim Eurasia's northwest and plate, so often experiences earthquake. Sighted by geological, Indonesian archipelago lies on appointment 2 mainearthquake bands, which is earthquake Sirkum Pacific and Alpide Transasiatic's earthquake band, in consequence Indonesia includes in ringband damp down Pacific (ring of fire). Ring damps down Pacific constitute world active mountain series causative Indonesian experience earthquakefrequency that adequately frequent. It bears out the importance for review strategical earthquake charges be in contemplation structure designin anticipation if happening earthquake. In common structure analysis to earthquake is divided as 2 kinds, which is static analysis and dynamicanalysis (respon spectrum analysis and time history analysis). This research has a purpose to know building structure performance bases drift anddisplacement. Observational method that is utilized is analisis dynamic time history by use of software ETABS. Buildings structure evaluationby give earthquake record note El Centro, Chi Chi Taiwan, Kobe Japan and Indonesian Sumatera. If building was given by charges El Centro'searthquake, Chi Chi Taiwan, Kobe Japan and Indonesian Sumatera is gotten safe to inspire angles nominal basic. Helper bounds performanceand ultimit's bounds performance that ineligible appropriate SNI 1726 2002 sections 8.1 and sections 8.2 is El Centro's earthquake record andIndonesia Sumatera. According to ATC-40, if building was given by charges El Centro's earthquake, Chi Chi Taiwan, Kobe Japan and IndonesianSumatera therefore building performance comes in category IO (Immediate Occupancy).

Kajian pengaruh variasi komposisi silica fume terhadap parameter beton memadat mandiri dengan kuat tekan beton mutu tinggi

Abstract: Seiring dengan perkembangan zaman, semakin banyak pula pembangunan infrastruktur di dunia. Pada era teknologi sekarang ini, timbulah berbagai inovasi untuk memodifikasi beton. High strength self compacting concrete (HS-SCC) atau beton mutu tinggi memadat mandiri merupakan salah satu inovasi dalam pembuatan beton. Di Indonesia sendiri saat ini sedang banyak melakukan penelitian mengenai pengadaan bahan alternatif sebagai pencampur atau pengganti semen pada beton SCC. Bahan tambah kimia yang digunakan berupa superplasticizer yang berguna untuk memudahkan dalam pengerjaan beton (workabilitas), sedangkan bahan tambah mineral yang digunakan adalah rice husk ash (abu sekam padi). Abu sekam padi berfungsi untuk meningkatkan kuat tekan beton karena bersifat pozzolannik dan mengandung unsur silika yang tinggi. Penelitian ini dilakukan untuk mengkaji pengaruh penambahan variasi komposisi rice husk ash pada beton mutu tinggi memadat mandiri. Dalam penelitian ini kandungan SiO 2 (silika) pada abu sekam padi sebesar 84,91% dan kadar variasi abu sekam padi yang digunakan sebesar 0%, 5%, 7,5%, 10% dan 12,5% terhadap berat semen. Benda uji yang digunakan berbentuk silinder berukuran 15 cm dan tinggi 30 cm. Pengujian yang dilakukan terhadap parameter self compacting concrete yaitu fillingability , passingability dan segregation resistance serta pengujian kuat tekan beton pada umur 14 dan 28 hari dengan menggunakan Compressing Testing Machine (CTM). Hasil penelitian menunjukkan bahwa beton dengan kadar variasi 5% abu sekam padi memberikan hasil yang baik untuk pengujian terhadap parameter self compacting concrete dan kuat tekan maksimal terjadi pada beton umur 28 hari dengan penambahan abu sekam padi 10%, yaitu 57,15 MPa.

Declining Performance of Silicone-Based Magnetorheological Elastomers after Accelerated Weathering.

Abstract: Magnetorheological elastomers (MRE)-based products are usually located in an area directly exposed to sunlight and rain. However, there is no specific research on the behavior of MRE after accelerated weathering. Therefore, in this study, the changes to the chemical and rheological properties of both isotropic and anisotropic MRE after accelerated weathering were examined. Treated and untreated specimens were compared. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample was prepared with 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine, Q-Sun Xe-1 Xenon Test Chamber, under a UV light exposure cycle and water spray. A material characterization was carried out using FTIR and a rheometer to determine the changes to the chemical and rheological properties. The morphological analysis results showed that after the weather treatment, the surface was rough and more cavities occurred. The rheometer test results showed a significant decrease in the storage modulus of each treated MRE specimen, unlike the untreated MRE specimens. The decrease in the storage modulus value with currents of 0, 1, 2, and 3 Amperes was 66.67%, 78.9%, 85.2%, and 80.5%, respectively. Meanwhile, FTIR testing showed a change in the wave peak between the untreated and treated MRE specimens. Thermogravimetric analysis (TGA) also showed a decrease in MRE weight for each specimen. However, for both treated and untreated MRE specimens, the decrease in TGA was not significantly different. In all the tests carried out on the MRE samples, weather acceleration treatment caused significant changes. This is an important consideration for developers who choose silicone as the MRE matrix.

Saturated Spectroscopy and Unsaturated Spectroscopy Comparative Study on Malignant and Benign Human Cancer Cells and Tissues with the Passage of Time under Synchrotron Radiation

Abstract: In the current study, we have experimentally and comparatively investigated and compared malignant human cancer cells and tissues before and after irradiating of synchrotron radiation using Saturated Spectroscopy and Unsaturated Spectroscopy, respectively.

Design and modeling of a magnetorheological valve with both annular and radial flow paths

Abstract: In this article, an MR valve possessing simultaneously annular fluid flow resistance channels and radial fluid flow resistance channels is designed, and its structure and working principle are described. In addition, a mathematical model for the MR valve with both annular and radial flow paths is developed and the simulation is carried out to evaluate the newly developed MR valve. The simulation results based on the proposed model indicate that the efficiency of the MR valve with circular disk-type fluid resistance channels is superior to that with annular fluid resistance channels under the same magnetic flux density and outer radius of the valve. Furthermore, the results also show that the efficiency of the MR valve can be improved significantly with two types of fluid flow resistance gaps, viz. annular fluid flow resistance gaps and circular disk-type fluid flow resistance gaps simultaneously.

Development and experimental characterization of a large-capacity magnetorheological damper with annular-radial gap

Abstract: Abstract Magnetorheological (MR) dampers with bypass arrangements and combined annular-radial fluid flow channels have shown superior performance compared to conventional MR dampers with single annular/radial fluid flow gaps. Achieving a higher controllable dynamic force range with low off-state but high on-state damping force is yet a significant challenge for developing MR dampers for high payload ground vehicle suspensions. This paper presents the conceptual design, fabrication, and experimental characterization of a mid-sized large-capacity MR damper equipped with a compact annular-radial MR fluid bypass valve. Extensive experimental tests were conducted to investigate the dynamic characteristics of the proposed MR damper considering wide ranges of excitation frequency, loading amplitude, and electrical current. The equivalent viscous damping and the dynamic range were calculated as functions of loading conditions considered. The proposed damper initially realized the maximum dynamic range and damping force of 2.3 and 5.54 kN, respectively. With MR valve design modifications, the maximum dynamic range and damping force were substantially increased, reaching 5.06 and 6.61 kN, respectively. The effectiveness of the proposed MR damper was subsequently identified by comparing its dynamic range with other conventional MR dampers in previous studies. The results confirmed the superior performance of the proposed MR damper and its potential application for highly adaptive suspension systems for off-road wheeled and tracked vehicles.

Modelling,Characterisation And Force TrackingControl Of A Magnetorheological Damper UnderHarmonic Excitation

Abstract: The objective of this paper is to study the performance of a sixth order polynomial approach to model hysteresis behaviour of a magnetorheological (MR) damper under harmonic excitations.The polynomial model is developed based on curve fitting from the experimental results and consists of a pair subsystem namely positive and negative acceleration which correspond to the upper and lower curves.The performance of the proposed polynomial model is compared with a well known non-parametric technique namely inverse model.The energy dissipated and equivalent damping coefficient of the MR damper in terms of input current and displacement amplitude are investigated.From the simulation results,the sixth order polynomial model shows better performance in describing non-linear hysteresis behaviour of the MR damper compared with inverse model.The force tracking control in both simulation and experimental studies demonstrate that a close-loop PI control has the ability to track the desired damping force well.

Development and experimental characterization of a large-capacity magnetorheological damper with annular-radial gap

Abstract: Magnetorheological (MR) dampers with bypass arrangements and combined annular-radial fluid flow channels have shown superior performance compared to conventional MR dampers with single annular/radial fluid flow gaps. Achieving a higher controllable dynamic force range with low off-state but high on-state damping force is yet a significant challenge for developing MR dampers for high payload ground vehicle suspensions. This paper presents the conceptual design, fabrication, and experimental characterization of a mid-sized large-capacity MR damper equipped with a compact annular-radial MR fluid bypass valve. Extensive experimental tests were conducted to investigate the dynamic characteristics of the proposed MR damper considering wide ranges of excitation frequency, loading amplitude, and electrical current. The equivalent viscous damping and the dynamic range were calculated as functions of loading conditions considered. The proposed damper initially realized the maximum dynamic range and damping force of 2.3 and 5.54 kN, respectively. With MR valve design modifications, the maximum dynamic range and damping force were substantially increased, reaching 5.06 and 6.61 kN, respectively. The effectiveness of the proposed MR damper was subsequently identified by comparing its dynamic range with other conventional MR dampers in previous studies. The results confirmed the superior performance of the proposed MR damper and its potential application for highly adaptive suspension systems for off-road wheeled and tracked vehicles.