Cylindrical Test Research Articles

Research on Improving Machining Productivity When External Cylindrical Grinding of 160Cr12Mo Steel

This paper presents the research carried out to improve machining productivity when conducting external cylindrical grinding of 160Cr12Mo steel on the basis of meeting requirement of surface roughness of workpiece. External cylindrical grinding test of 160Cr12Mo steel was based on the optimal test matrix based on symmetrical D with Al2O3 grinding wheel. The test data was analyzed to develop regression function to show the relationship between surface roughness with cutting parameters including cutting velocity, depth of cut and feed rate. Basing on this regression equation, the level of influence of each cutting parameters on surface roughness of workpiece was determined, thereby solutions could be found to improve grinding productivity by increasing the depth of cut but meeting the required roughness value. The test was carried out when it was desirable to improve machining productivity but meeting the machining surface having small roughness. The results showed that it is feasible to increase the depth of cut to increase machining productivity up to 1.8 times while the surface roughness also increases only about 0.6 m.

Effect of contact load upon attrition-corrosion wear behavior of bio-composite materials: In vitro off-axis sliding contact-chewing simulation

Background: In recent years, the use of composite materials as biomaterials has been increasing in dentistry. It is important to perform in vitro experiments of biomaterials before living tissue. Aim: The purpose of this work was to examine the effect of contact load upon attrition-corrosion wear behavior of bio-composite materials: in vitro off-axis sliding contact chewing simulation. Material and Method: In this study, 2 mm × 12 mm (weight × diameter) cylindrical test specimens were prepared from Filtek Supreme and Clearfil AP-X bio-composite materials with different filler structure. The surface roughness and Vicker's Hardness values of the bio-composites were measured before the wear test procedures. Then, the test specimens were subjected to off-sliding abrasion test procedures under different mechanical loads in artificial saliva and citric acid medium. Wear volume loss of bio-composite materials was determined after wear test procedures using the three-dimensional noncontact profilometer. Results: As the mechanical loading increased, the loss of wear volume in both composite materials increased irrespective of test medium. However, this increase in wear volume loss in test specimens was more pronounced in the citric acid environment. Conclusion: As a result of, the organic matrix structure (such as Ba glass particle) of the composite material contributes to more volume loss in corrosive environment.

Prediction on Compressive and Split Tensile Strengths of GGBFS/FA Based GPC.

Based on rate constant concept, empirical models were presented for the predictions of age-dependent development of compressive and split tensile strengths of geopolymer concrete composite (GPCC) with fly ash (FA) blended with ground granulated blast furnace slag (GGBFS). The models were empirically developed based on a total of 180 cylindrical test results of GPCC. Six different independent factors comprising of curing temperature, the weight ratios of GGBFS/binder, the aggregate/binder, the alkali solution/binder, the Na2SiO3/NaOH, and the NaOH concentration were considered as the variables. The ANOVA analyses performed on Taguchi orthogonal arrays with six factors in three levels showed that the curing temperature and ratio of GGBFS to binder were the main contributing factors to the development of compressive strength. The models, functionalized with these contributing factors and equivalent age, reflect the level of activation energy of GPCC similar to that of ordinary Portland cement concrete (OPC) and a higher frequency of molecular collisions during the curing period at elevated temperature. The model predictions for compressive and split tensile strength showed good agreements with tested results.

RKDG method for 2D gas dynamics simulation on uniform rectangular meshes

This paper is devoted to a numerical simulation of 2D gas dynamics flows on uniform rectangular meshes using the Runge - Kutta - Discontinuous - Galerkin (RKDG) method. The RKDG algorithm was implemented with in-house C++ code based on the experience in the investigation of 1D case. The advantage of the RKDG method over the most popular finite volume method (FVM) is discussed: three basis functions being applied in the framework of the RKDG approach lead to a considerable decrease of the numerical dissipation rate with respect to FVM. The results of the acoustic pulse simulation on a sufficiently coarse mesh with the piecewise-linear approximation show a good agreement with the analytical solution in contrast to the FVM numerical solution. For the Sod problem, the results of the discontinuities propagation illustrate the dependence of the scheme resolution on the numerical fluxes, troubled cell indicator and the limitation technique choice. The possibility to resolve strong shocks is demonstrated with the Sedov cylindrical explosion test.

Confinement influence in cracking areas single reinforced concrete

The combination of concrete and reinforcement in collaboration with the load is determined by the perfect bond of the two materials. The axial load is given in reinforced concrete results in internal cracking of reinforced concrete around the threaded reinforcement area. An area within the radius of cracking of the concrete around the reinforcement has also been obtained. The action is needed to reduce the area of cracked concrete by giving restraints using spherical spiral reinforcements within the concrete crack radius. It is expected to increase the strength of the reinforcement and concrete around it. The methodology used is Pull Out on single reinforced concrete cylindrical specimens with confinement and without confinement. Concrete cylindrical test specimens with a diameter of 150 mm 200 mm high with single reinforcement with a diameter of 10 mm, and spiral reinforcement as confinement with an identification diameter of 4 mm. Placed within the radius of cracking of the concrete around the reinforcement. The Pull Out test results indicate a cesarean movement from the edge that is loaded to the free end. The restrained specimen produces a larger cesarean at the end of the load, when the initial cesarean occurs at the free end.

An accurate and reliable operational transfer path analysis for transfer path contribution evaluation based on Landweber iterative method

To improve the accuracy and reliability of operational transfer path analysis (OTPA) in transfer path identification and path contribution evaluation, Landweber-iterative-method-based OTPA is proposed in this paper. Firstly, the vibration data at the reference points and the target points in the operating conditions are obtained. Secondly, the appropriate iteration model and the iterative termination criterion of the Landweber iterative method are designed to improve the fitting degrees of the transmissibility function matrix. Thirdly, the transmissibility function matrix is obtained using the data in experimental operating conditions. Finally, transfer path identification and contribution evaluation are carried out in practical operating conditions, and the major transfer paths are identified. Furthermore, the accuracy, reliability and noise tolerance capability of the proposed method are comparatively studied with truncated singular value decomposition and Tikhonov-regularization-based OTPA, according to typical numerical case studies and experimental case studies on a cylindrical test bed. Generally, the proposed method can obviously improve the accuracy and reliability of transfer path identification and path contribution evaluation, and provide significant evidence for vibration reduction and the control of mechanical systems.

Finding dimensional stability considering deflection effects in cylindrical plunge grinding

In spite of the existence of several models to effectively design grinding cycles, they are not frequently adopted in production lines, due to the lack of knowledge, difficulties in determining some input parameters and discrepancies observed in the obtained results during the production of a batch of parts. This paper proposes a contribution to the modeling and simulation of cylindrical plunge grinding cycles in terms of dimensional stability of the process, prediction of the workpiece diameter along the grinding cycle and the minimum required spark-out time, incorporating into the model grinding tolerance limits according to the chosen capability scenario. The prediction of the part diameter and the spark-out time in a cylindrical plunge grinding operation is the key parameter to design optimized grinding cycles. The proposed model covers typical fast grinding cycles in industry, in which the spark-in time is not long enough to guarantee that at its end, the real workpiece radius reduction speed is very close to the programmed feed rate. In the proposed model, the remaining radial stock to be removed during the spark-out stage is designed to be equal to or lower than the tolerance limit for the grinding operation, but considering different scenarios of capability index: barely capable process (Cp= 1); capable (Cp= 1.3); and six-sigma quality level (Cp= 2.0). The minimum spark-out time necessary to reduce the total radial stock to the specified capability limit is calculated by the simulation. Experimental plunge cylindrical grinding tests were performed in which the reduction in the workpiece diameter was measured using an in-process diameter gauge, varying the in-feed velocity and the spark-out time. As a result, a reasonable compromise between the proposed theoretical model and the experimental data was achieved. The dependency of the “time constant” and the in-feed speed was demonstrated for fast spark-in cycles. It was also observed that longer spark-out times will be needed to achieve tighter capability indexes for a given in-feed speed and “time constant” value.

Influence of Cooling Methods on the Residual Mechanical Behavior of Fire-Exposed Concrete: An Experimental Study.

This work reports the main conclusions of a study on the mechanical behavior of concrete under ISO 834 fire with different cooling methods. The aim of this research was to provide reliable data for the analysis of structures damaged by fire. The experimental program used cylindrical concrete test specimens subjected to ISO 834 heating in a furnace up to maximum gas temperatures of 400, 500, 600, 700, and 800 °C. The compressive strength was measured in three situations: (a) at the different temperature levels reached in the furnace; (b) after a natural cooling process; and (c) after aspersion with water at ambient temperature. The results indicate that the concrete residual compressive strength is fairly dependent on the maximum temperature reached in the furnace and revealed that concrete of a lower strength preserved relatively higher levels of strength. The cooling method significantly influenced the strength, albeit at a lower intensity. In all cases, the residual strength remained in the range of 38% to 67% of the strength at ambient temperature. The statistical analysis showed that the data obtained by the experimental program are significant and confirmed the influence of the conditions imposed on the residual strength.

The Benefits of Adding Corn Stalk Ash as a Substitution of Some Cement Against of Compressive Strength Concrete

Concrete is a very important building material used in the world of construction services, and it is generally known that the good and bad properties of concrete can be seen from its compressive strength. Concrete consists of Portland Cement (PC) or other hydraulic cement, fine aggregates, coarse aggregates, and water, with or without using additional materials. Cement is one of the main mixtures of concrete constituents composed of natural resources such as lime (CaO), Silica (SiO₃), alumina (Al2O₃), little magnesia (MgO), and alkali. Silica is also found in corn. according to (Roesmarkam and Yuwono, 2002) corn plants have a Silica content of 20.6%. This study aims to determine the effect of utilization of corn stalk ash on compressive strength and modulus of elasticity of concrete. Cornstalk ash is used as a partial substitute for cement, with a mixture composition of 2%, 4%, 6%, 8%, and 10%.
 This study uses SNI 03-2834-2000 for mix design, with the added ingredient of 0.25% sikament NN. Cylindrical test specimen size (150 mm x 300 mm), the specimen was treated and tested at 28 days. Based on research using corn stalk ash 2%, 4%, 6%, 8%, and 10%. either without or using sikament NN the highest compressive strength at 8% is 20.8 Mpa and 20.4 Mpa, and decrease in usage of 10% corn stalk ash which is 18.2 Mpa and 18, 4 Mpa. The highest elastic modulus without or with sikament NN present in 8% ie 21656.14 Mpa and 21607.52 MPa. Modulus of Elasticity value decreased in the use of corn stalks 10% ash is 20366.28 Mpa and 20569.59 MPa. Based on the research, corn stalk ash can replace the role of part of cement in construction using corn stalk ash 8%.

Behavior of the Density Interface of Helium Stratification by an Impinging Jet

This study observed the breakup of helium stratification, which was 30 vol % helium in air and formed in the upper part of a cylindrical test vessel with a height of 9.5 m and a diameter of 3.4 m. An air jet collided with the density interface on which the restoring buoyancy of the helium and the disturbing inertial force of the impinging jet were balanced. The Reynolds number of the jet was about 20 000 at the exit of a vertical pipe located 3.0 m below the initial stratification. The helium concentration was measured by sampling the gas mixture with thermal conductivity analyzers. Particle image velocimetry (PIV) visualized the flow field of the jet impinging on the density interface. The density interface was clearly shown by the binary images generated from the number of tracer particles for the PIV. From the continuous impinging jet, the density interface gradually moved upward. The interaction Froude number, which was defined by the ratio of the inertial force of the impinging jet to the buoyancy of a light gas on the density interface, was about unity calculated by the helium concentration and the flow visualization. The density interface went up to 0.0002 m/s.

Convolutive blind source separation in frequency domain with kurtosis maximization by modified conjugate gradient

Abstract To efficiently and accurately separate sources from the measured signals and align their permutation, a convolutive blind source separation (BSS) in frequency domain with kurtosis maximization (CBSS_FDKM) by the modified conjugate gradient is proposed. Firstly, Short Time Fourier Transform (STFT) is used to convert the convolutive BSS problem in time domain into an instantaneous BSS in frequency domain. Secondly, CBSS_FDKM is adopted to separate complex signals in each frequency bin, and kurtosis maximization is used as the objective function and optimized by a modified conjugate gradient with iterative step sizes optimized by an efficient algebraic method, and thus the accuracy and convergence speeds are significantly enhanced. Thirdly, the power spectra are obtained from the separated signals and the cosine distances based on power spectra are calculated for permutation alignment. Finally, inverse Short Time Fourier Transform (ISTFT) is adopted to reconstruct the separated signals in time domain. Furthermore, the accuracy and robustness of the proposed method are comparatively studied according to typical numerical studies and experimental studies on a cylindrical test bed. Generally, this paper provides a more accurate and robust BSS for source separation and identification, which can provide significant evidences for vibration & noise monitoring and control.

A Surface Preparation Machine for Cylindrical Mechanical Test Specimens

A surface preparation machine which can provide a controlled surface condition for mechanical test specimens has been developed. The apparatus includes mechanical and electrical systems that have been designed with a simplified manufacturing processes employing extensive additive manufacturing. Experiments were carried out to evaluate the capability and repeatability of this machine. It has been shown that the machine provides an effective methodology to prepare cylindrical specimens with a high level of automation. Specifically, the machine provides the ability to control four active axes, grinding time and speeds as well as levels of lubrication beyond what grinding media employed. The application of the machine on aluminum specimens is described.

A benchtop UV irradiator for 3D dosimetry laboratories with dose considerations in a spinning NMR test tube

Many different chemical radiation dosimeters have been fabricated over the last 20 years. In the search for new dosimeters, next to being sensitive to clinical radiation doses, several other physicochemical characteristics need to be satisfied, such as stability of the dose response, spatial integrity, temperature independence, dose rate independence and tissue equivalence. The development of new dosimeters is often hindered by a limited access to radiation facilities to irradiate hundreds of test tubes or cuvettes to study these physicochemical properties. To facilitate this basic experimental research, we propose the use of an inexpensive UVC irradiator. While care is required in extrapolating the results obtained with UV radiation to high energetic X-rays, for several studies, a UV irradiator is a handy tool for first line investigation of new dosimeters. In this study, we calculated the dose distribution in a cylindrical test tube when being rotated during UV exposure. A quantitative analysis allows the optimization of the set-up to obtain dose rates in the sample in similar order of magnitude that are delivered at a clinical Linac. Regardless the usefulness of a UVC irradiator in the laboratory for preliminary testing, it should not be a complete replacement for measurements with high energetic X-rays.

Artificially prepared Reclaimed Asphalt Pavement (RAP)-an experimental investigation on re-recycling.

In this paper, the possibility of using different amounts of re-recycled (repeated recycled) Reclaimed Asphalt Pavement (RAP) in the asphalt mixture was experimentally investigated. First, a single virgin mixture was prepared and artificially aged to simulate the first generation of RAP to be used for designing the first generation of recycled mixtures. Next, the recycled mixtures were further aged to obtain a second generation of RAP to be mixed for preparing the second generation of recycled mixtures with and without the contribution of a rejuvenator. The fatigue behavior and low-temperature properties of all asphalt mixtures were experimentally investigated based on the cylindrical indirect tensile test (CIDT), Bending Beam Rheometer (BBR) mixture creep stiffness tests, and Semi-Circular Bending (SCB) fracture tests, respectively. Results indicate that re-recycled materials designed with and without rejuvenator show inferior fatigue behavior with respect to the first generation of recycled mixtures while exhibiting better performance than the virgin material. Meanwhile, poorer low-temperature creep properties were observed for the mixture prepared with recycled and re-recycled RAP. Fracture properties comparable with those of the virgin material were obtained only for re-recycled mixtures designed with rejuvenator. The present experimental work provides evidence on the possibility of using re-recycled RAP up to 40% when rejuvenators are included in the mix design.

Investigating the Utilization of Ground Palm Kernel Shells for Partial Replacement of Cement in Concrete Using Nondestructive Method

The objective of this research is to investigate the utilization of palm kernel shells in ground form (GPK) for partial replacement of ordinary Portland cement (OPC) in concrete by investigating its optimal strength using nondestructive ultrasonic pulse velocity method for both cubic and cylindrical concrete test specimen. In all a total of 135 cubes and 66 cylinders of concrete were prepared. The dimension of the cubic concrete specimens was 150 × 150 × 150 mm and that of the cylindrical specimens were 110 mm and 500 mm diameter and length respectively. The mix design of the GPK shells used as a partial replacement for OPC ranged between 0% and 50% by weight of cement using mix ratio of 1:2:4 with water to cement ratio of 0.8. The concrete specimens were test at curing periods of 7 days, 28 days and 60 days for the cubes and 7 days and 28 days for the cylinders. Based on the results and the analysis done, it was generally observed in all cases that, as the mix ratio is increased, the ultrasonic pulse velocity, modulus of elasticity and the density decreased and as the curing period increased, these values increased across all the mix ratios. The ultrasonic pulse velocity and the density of the specimens shows that concretes containing GPK “fuel” shells has higher values than those containing GPK ordinary shells. Generally, the density, ultrasonic pulse velocity and the modulus of elasticity of concrete containing GPK shells decrease as the replacement percentage increase.

Studi Kuat Tekan Beton Speedcrete Dengan Zat Additive Naphthalene Berdasarkan Variasi Umur

This research aims to determine the maximum compressive strength value of concrete speedcrete using naphthalene additive additive at each test age and compare with normal concrete 28 days. This research used cylindrical test object with diameter 15 cm and height 30 cm. Speedcrete concrete does not undergo the treatment process while the normal concrete test object through the treatment process. Testing compressive strength of concrete speedcrete using Crushing Test Machine tool. In this research the compressive strength was produced by using superplasticizer type naphthalene and compared with normal concrete without using additive. The target quality plan is fc '35 MPa with the use of additive dose of 1.7% of the weight of cement. The results of this research showed an increase in the value of compressive strength of concrete speedcrete with aadditive materials added naphthalene increased with increasing age of concrete. The results showed that the compressive strength of concrete speedcrete with naphthalene additive materials of 12 hours, 18 hours, 28 hours and 48 hours was 0.5 MPa, 17,81 MPa, 31,14 MPa and 45,77 MPa. Normal strength concrete strength with the addition of 20% water age 28 days that is equal to 54.76 MPa.

Mechanical Properties of Wood Fiber Reinforced Geopolymer Composites with Sand Addition

ABSTRACT Fly ash-based geopolymers can be considered as a greener alternative to ordinary Portland cement, featuring comparable properties and cost yet with lower CO2 emissions. New wood fiber reinforced geopolymer composites with sand addition (WFSGC) have been synthesized at room temperature by mixing powder (fly ash, sand and randomly reinforced wood fiber) with sodium silicate and sodium hydroxide as alkaline activators. New WFSGC were cured at 90°C for 24 h. The design and investigation of WFSGC were based on a fix 5 wt.% percentage of sand, with variable wood fiber (5, 10, 15, 20, 25, 30 and 35 wt.%) and fly ash percentages. These WFSGC showed decreasing mechanical properties with increasing wood fiber addition as measured by the compressive strength at the cylindrical test (21.76–42.52 MPa), the compressive strength at the cubic test (31.79–39.17 MPa), the force load at upper yield at the cylindrical test (1.27–3.58KN), the flexural strength (7–10.76 MPa), compressive modulus at the cylindrical test (590,75–1021.17 MPa), the compressive modulus at cubic test (787.92–1059.79 MPa) and the flexural modulus (298.03–737.83 MPa). The density of WFRGC decreases with the addition of wood fiber (1.49–1.71 g/cm3). WFSGC with addition wood fibers up to 15 wt.% could be the limit for a promising green material for construction.

Modeling Flaw Pulse-Echo Signals in Cylindrical Components Using an Ultrasonic Line-Focused Transducer with Consideration of Wave Mode Conversion.

Investigations on flaw responses can benefit the nondestructive testing of cylinders using line-focused transducers. In this work, the system function, the wave beam model, and a flaw scattering model are combined to develop an ultrasonic measurement model for line-focused transducers to predict flaw responses in cylindrical components. The system function is characterized using reference signals by developing an acoustic transfer function for line-focused transducers, which works at different distances for both planar and curved surfaces. The wave beams in cylindrical components are modeled using a multi-Gaussian beam model, where the effects of wave mode conversion and curvatures of cylinders are considered. Simulation results of wave beams are provided to analyze their propagation behaviors. The proposed ultrasonic measurement model is certified from good agreement between the experimental and predicted signals of side-drilled holes. This work provides guidance for evaluating the detection ability of line-focused transducers in cylindrical component testing applications.

Post-cyclic volumetric strain of calcareous sand using hollow cylindrical torsional shear tests

Post-cyclic settlement of saturated soil, due to dynamic loadings such as earthquake, causes severe damage to structures. Dissipation of excess pore water pressure generated during cyclic loadings results in the volumetric strain of soil materials. Many studies have been conducted on factors affecting post-cyclic volumetric strain (εre,v) of siliceous soils. The effect of important factors on post-cyclic settlement of calcareous sand is evaluated in this study. Calcareous soils are generally located in tropical and subtropical areas near oceans and gulfs. These deposits are usually saturated and consequently, post-cyclic settlement can be critical in these sediments. In this research, a series of hollow cylindrical torsional shear tests were performed on Hormuz calcareous sands obtained from the north coast of the Persian Gulf. The samples were loaded cyclically under different cyclic stress ratios (CSRs) in undrained condition and then, terminated at a desired pore water pressure ratio (ru). After that, the excess pore water pressure was allowed to dissipate, and volumetric strain occurred as a result. The effects of relative density (Dr), cyclic stress ratio (CSR), excess pore water pressure ratio (ru) and maximum cyclic-induced shear strain (γmax) on εre,v of the reconstituted sand were evaluated. The results showed that maximum shear strain is the most effective factor in estimating the post-cyclic settlement of the calcareous sand.

Predicting of uniaxial compressive strength of some igneous and metamorphic rocks by block punch index and cylindrical punch index tests

Uniaxial compressive strength (UCS) of rock materials is a crucial parameter in designing of engineering structures to be constructed in/on rock masses. Although the suggested methods for determination of UCS are well known and required relatively simple procedures, preparation of standard core specimens may not be easy for rock materials of heavily jointed rock and/or thinly stratified rock masses. In order to overcome these difficulties to be encountered during sample preparation, the studies on the alternative equations based on results of simple index tests for predicting of UCS of rock materials have been popular. A linear correlation with conversion factor of 5.1 was suggested in literature for predicting of UCS from block punch index (BPI) considering a wide variety of rock types. In this study, the relations were investigated to be used for predicting of UCS from BPIc and also cylindrical punch index (CPI) based on experimental studies employed on seven different igneous and metamorphic rocks, collected from different locations in Hamedan province, west of Iran. The linear regression analysis showed that the conversion factor between UCS and BPIc was obtained as 5.7 for the tested rocks, which is already higher than the proposed value of 5.1. A conversion factor equal to 7.4 was derived for relation between UCS and CPI. In addition, the prediction performance of some well-known equations on the test results obtained in this study for determination of UCS from BPIc, and also CPI were evaluated. Moreover, the coefficients of determination of logarithmic and power functions were higher than any other functions for UCS–BPIc and UCS-CPI relations, respectively.