Conical Tip Wear in Transition Deformation – Wear Map Construction under Cyclic Impact of Hardness Ceramic Materials

2015 ◽  
Vol 723 ◽  
pp. 804-813
Author(s):  
Constantin Tiganesteanu ◽  
Lucian Capitanu ◽  
Virgil Florescu
Keyword(s):  
Reaction Force ◽  
Experimental Tests ◽  
Ceramic Materials ◽  
Analytical Relationship ◽  
Maximum Pressure ◽  
Wear Volume ◽  
Map Construction ◽  
Cyclic Impact ◽  
The Impact ◽  
Account Variation

Penetrator tip wear was investigated on an apparatus testing the impact on hard ceramic materials. The experimental tests were done on a vertical impact computerized test bench of original conception. Tapered diamond and carbide-metal pins were used as penetrators. It was noticed that in some situations the tip of the penetrator remained stuck in its target, acting as a Morse cone, due to the friction force between the penetrator and its target being higher than the reaction force of the collision between the two objects. This has led us to choose an angle of 1060 at the tip of the penetrator cone. For most tests we used a maximum strength of 40 N and a sintered carbide impact pin with a 1150 HV 30/15 hardness. For the study of the penetrator tip wear we have used a granite tile that owing to its high hardnes has enabled a noticeable wear of the tip. We have established a method and an algorithm for calculating the tip wear, based on images captured under a microscope after testing. A general finding is that in all tests, besides the cyclical impact deformation and the wear of coating that were tested, the wear of the tip of the pin which applies the impacts is also noticeable regardless of its shape (spherical, conical, etc), so much so that for a large number of cyclical impacts the pin tip wear must be taken into account. Variation curves are presented in the volume of wear material and of the maximum pressure p0 at the tip of the impactor, depending on the number of impacts. From the variation curve of the wear volume of material according to the number of impacts we’ve established an analytical relationship for the wear of the tip. A logarithmic formula allows for a relative assessment of the extent to which the tip is worn, as a function of the total number of incurred impacts.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

scholarly journals Simulation of Energy Absorption Performance of the Couplers in Urban Railway Vehicles during a Heavy Collision

Machines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 91
Author(s):  
Sunghyun Lim ◽  
Yong-hyeon Ji ◽  
Yeong-il Park
Keyword(s):  
Reaction Force ◽  
Crash Test ◽  
Railway Vehicle ◽  
Buffer System ◽  
Railway Vehicles ◽  
Hydraulic Shock Absorber ◽  
Coupling Buffer ◽  
Absorption Performance ◽  
Different Characteristics ◽  
The Impact

Railway vehicles are generally operated by connecting several vehicles in a row. Mechanisms connecting railway vehicles must also absorb front and rear shock loads that occur during a train’s operation. To minimize damage, rail car couplers are equipped with a buffer system that absorbs the impact of energy. It is difficult to perform a crash test and evaluate performance by applying a buffer to an actual railway vehicle. In this study, a simulation technique using a mathematical buffer model was introduced to overcome these difficulties. For this, a model of each element of the buffer was built based on the experimental data for each element of the coupling buffer system and a collision simulation program was developed. The buffering characteristics of a 10-car train colliding at 25 km/h were analyzed using a developed simulator. The results of the heavy collision simulation showed that the rubber buffer was directly connected to the hydraulic shock absorber in a solid contact state, and displacement of the hydraulic buffer hardly occurred despite the increase in reaction force due to the high impact speed. Since the impact force is concentrated on the vehicle to which the collision is applied, it may be appropriate to apply a deformation tube with different characteristics depending on the vehicle location.

Study on Grinding Force in Two-Dimensional Ultrasonic Grinding Nano-Ceramics

2010 ◽  
Vol 42 ◽  
pp. 204-208 ◽  
Author(s):  
Xiang Dong Li ◽  
Quan Cai Wang
Keyword(s):  
Mathematical Model ◽  
Ultrasonic Vibration ◽  
Contact Time ◽  
Reaction Force ◽  
Grinding Force ◽  
Two Dimensional ◽  
Indentation Fracture ◽  
Ultrasonic Grinding ◽  
The Impact ◽  
Ultrasonic Vibration Assisted Grinding

In this paper, the characteristic of grinding force in two-dimensional ultrasonic vibration assisted grinding nano-ceramic was studied by experiment based on indentation fracture mechanics, and mathematical model of grinding force was established. The study shows that grinding force mainly result from the impact of the grains on the workpiece in ultrasonic grinding, and the pulse power is much larger than normal grinding force. The ultrasonic vibration frequency is so high and the contact time of grains with the workpiece is so short that the pulse force will be balanced by reaction force from workpiece. In grinding workpiece was loaded by the periodical stress field, which accelerates the fatigue fracture.

Overview of EAF Screening Results on the 900 MWe NPP French Fleet

2016 ◽  
Author(s):  
Thomas Métais ◽  
Nicolas Robert ◽  
Pierre Genette ◽  
Nicolas Etchegaray
Keyword(s):  
Power Plants ◽  
Screening Method ◽  
Experimental Tests ◽  
Degradation Process ◽  
Primary System ◽  
Transfer Coefficients ◽  
Screening Process ◽  
The Usa ◽  
License Renewal ◽  
The Impact

In the wake of numerous experimental tests carried out in air and also in a PWR environment, both abroad and in France, an update of the current thermal fatigue codification is underway in France. Proposals are currently being integrated in the RCC-M code [1]. In parallel, it is necessary to evaluate the impact of codification evolution on the RCS components. In the USA, such evaluations have already been implemented for license renewal to operate power plants beyond their initial 40 years of operation. In order to reduce the scope of the calculations to perform, a preliminary screening was carried out on the various areas of the primary system components: this screening is detailed in an EPRI report [2]. The output of this screening process is a list of locations that are most prone to EAF degradation process and it is on these zones only that detailed EAF calculations are carried out. In France, a similar approach was defined in the perspective of the fourth ten-year visit of the 900 MWe plants (VD4 900 MWe) so as to map out all the locations that are most impacted by EAF and hence concentrate the calculation effort on these specific areas for the VD4 900 MWe. In that respect, a specific methodology to evaluate the factor to account for environmental effects or Fen [3] based on correlations [4] for hot and cold shocks was established. These correlations use data that is readily accessible in transient description documents and stress reports such as temperature change, heat transfer coefficients, ramp duration and geometry. The need for these correlations is specific to the French context due to a need for a preliminary and yet precise idea of the overall impact of the modifications brought to the RCC-M code in fatigue before the VD4 900 MWe. This paper presents the results of the screening method that was applied to the whole RCS of the 900 MWe NPP fleet.

Experimental Investigation and Characterization of the Rotating Stall in a High Pressure Centrifugal Compressor: Part II — Influence of Diffuser Geometry on Stage Performance

2002 ◽  
Author(s):  
G. Ferrara ◽  
L. Ferrari ◽  
C. P. Mengoni ◽  
M. De Lucia ◽  
L. Baldassarre
Keyword(s):  
Experimental Tests ◽  
Rotating Stall ◽  
Geometric Parameters ◽  
Flow Coefficient ◽  
Low Flow ◽  
Main Task ◽  
Stage Performance ◽  
The Impact ◽  
Prediction Criteria

Extensive research on centrifugal compressors has been planned. The main task of the research is to improve present prediction criteria coming from the literature with particular attention to low flow coefficient impellers (low width to radius ratios) where they are no more valid. Very little data has been published for this kind of stages, especially for the last stage configuration (with discharge volute). Many experimental tests have been planned to investigate different configurations. A simulated stage with a backward channel upstream, a 2D impeller with a vaneless diffuser and a constant cross section volute downstream constitute the basic configuration. Several diffuser types with different widths, pinch shapes and diffusion ratios were tested. The effect of geometric parameters on stage stability has been discussed inside part I of the present work; the purpose of this part of the work is to illustrate the effect of the same geometric parameters on stage performance and to quantify the impact of stability improvements on stage losses.

scholarly journals Experimental Investigation on the Effect of Shot Peening and Deep Rolling on the Fatigue Response of High Strength Fasteners

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1093 ◽  
Author(s):  
Reggiani
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Tests ◽  
Published Data ◽  
Deep Rolling ◽  
Beneficial Impact ◽  
The Impact ◽  
Fatigue Life Enhancement

Shot-peening and deep rolling are mechanical surface treatments that are commonly applied to enhance the fatigue performances of components, owing to their capacity to generate compressive residual stresses and induce work hardening. However, literature is still poor of published data concerning the application of these treatments to high strength steels fasteners, although these represent a class of components among the most widespread. In the present work, the impact of deep rolling and shot-peening performed in the underhead radius of two set of fasteners made of 36NiCrMo and 42CrMoV for fatigue life enhancement has been investigated. The experimental tests consisted of six combinations of shot-peening and deep rolling, including the non-treated state. Two test campaigns have been sequentially carried out with different process parameters and treatment sequences. The results always showed a beneficial impact of the deep rolling on fatigue, especially for the 42CrMoV steel. Conversely, the effect of the shot-peening strongly depended on the selected set of parameters, alternatively leading to an improvement or a worsening of the fatigue life in relation to the level of induced surface roughness.

scholarly journals Experimental Investigation and Statistical Approach to Wear Characterization of Plasma Nitrided AISI 4140 Steel-A Case Study

2017 ◽  
Vol 15 (1-2) ◽  
Author(s):  
Santosh V. Bhaskar ◽  
Hari N. Kudal
Keyword(s):  
Plasma Nitriding ◽  
Interaction Effects ◽  
Wear Volume ◽  
Effective Parameters ◽  
Operational Parameters ◽  
Sliding Speed ◽  
Aisi 4140 Steel ◽  
Study Results ◽  
Aisi 4140 ◽  
The Impact

<p>Components of forming tool dies such as draw ring, ejector pin use AISI 4140 as material for their manufacturing. The integrity of the die cutting tools is essential to achieve adequate product quality. In present study, the influence of plasma nitriding (PN) on the wear behav-iour of AISI 4140 steel was investigated. Full factorial experimental design technique was used to study the main effects and the interaction effects between operational parameters and the response variable. The control factors at their two levels (-1 and +1) were: applied load (4.905N and 14.715N), sliding speed (3.14 m/s and 5.23 m/s), and sliding distance (500m and 1000m).The parameters were coded as A, B, and C, consecutively, and were investigated at two levels (-1 and +1). Response selected was Wear Volume Loss (WVL). The effects of in-dividual variables and their interaction effects for dependent variables, namely, WVL were determined. The process of selecting significant factors, based on statistical tools, is illustrat-ed. Analysis of Variance (ANOVA) was performed to know the impact of individual factors on the WVL. Untreated and PN treated AISI 4140 specimens were investigated using field emission Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray (EDX) analyzer. Finally diagnostics tools were used to check adequacy of the model in terms of assumptions of ANOVA. ‘Design Expert-7’ and ‘Minitab 17’ softwares were used in the study. Results of statistical analysis indicate that the most effective parameters in the WVL were load and sliding speed. The interaction between load and sliding speed was the most influencing interaction. Results of regression analysis indicate regression coefficient (R2) to be above 90% which suggests good predictability of the model. ‘Predicted-R2’ and ‘Adjusted-R2’, found to be in good agreement with R2, for both the materials under investigation. More-over, results of SEM microscopy suggest PN to be an effective technique to reduce wear.</p>

scholarly journals Numerical and experimental analyses for the improvement of surface instant decontamination technology through biocidal agent dispersion: Potential of application during pandemic

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251817
Author(s):  
Paulo Roberto Freitas Neves ◽  
Turan Dias Oliveira ◽  
Tarcísio Faustino Magalhães ◽  
Paulo Roberto Santana dos Reis ◽  
Luzia Aparecida Tofaneli ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Cfd Simulations ◽  
New Device ◽  
Qualitative And Quantitative ◽  
Droplet Concentration ◽  
Computational Fluid Dynamics Cfd ◽  
Suspended Droplet ◽  
The Impact ◽  
Disinfection Chamber ◽  
Important Form

The transmission of SARS-CoV-2 through contact with contaminated surfaces or objects is an important form of transmissibility. Thus, in this study, we evaluated the performance of a disinfection chamber designed for instantaneous dispersion of the biocidal agent solution, in order to characterize a new device that can be used to protect individuals by reducing the transmissibility of the disease through contaminated surfaces. We proposed the necessary adjustments in the configuration to improve the dispersion on surfaces and the effectiveness of the developed equipment. Computational Fluid Dynamics (CFD) simulations of the present technology with a chamber having six nebulizer nozzles were performed and validated through qualitative and quantitative comparisons, and experimental tests were conducted using the method Water-Sensitive Paper (WSP), with an exposure to the biocidal agent for 10 and 30 s. After evaluation, a new passage procedure for the chamber with six nozzles and a new configuration of the disinfection chamber were proposed. In the chamber with six nozzles, a deficiency was identified in its central region, where the suspended droplet concentration was close to zero. However, with the new passage procedure, there was a significant increase in wettability of the surface. With the proposition of the chamber with 12 nozzles, the suspended droplet concentration in different regions increased, with an average increase of 266%. The experimental results of the new configuration proved that there was an increase in wettability at all times of exposure, and it was more significant for an exposure of 30 s. Additionally, even in different passage procedures, there were no significant differences in the results for an exposure of 10 s, thereby showing the effectiveness of the new configuration or improved spraying and wettability by the biocidal agent, as well as in minimizing the impact caused by human factor in the performance of the disinfection technology.

scholarly journals Experimental tests of the impact of selected parameters on the indentation rolling resistances

2018 ◽  
Vol 29 ◽  
pp. 00002 ◽  
Author(s):  
Dariusz Woźniak ◽  
Lech Gładysiewicz ◽  
Martyna Konieczna
Keyword(s):  
Main Part ◽  
Rolling Resistance ◽  
Experimental Tests ◽  
Conveyor Belt ◽  
Significant Component ◽  
Different Types ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors ◽  
The Impact

Belt conveyors are main part of transporting systems in mines and in many other branches of industry. During conveyor belt works different types of resistances are generated. Indentation rolling resistance is the most significant component of the resistances from the perspective of energy losses and it cause the biggest costs as well. According to latest state of analyses and measurements it is well known that theoretical rolling resistance were underestimated in comparison with the measured in-situ one. In this paper new method for determination indentation rolling resistance is presented. The authors compared theoretically and experimentally established damping factors. The relation between these two values enabled to obtain more precise equation for damping function. This function is one of the most important component in calculation of the rolling resistance. In new theoretical model value of rolling resistance is nearly twice higher than this used so far.

Experimental Study of the Bond of FRP Applied to Natural Stones and Masonry Prisms

2014 ◽  
Vol 624 ◽  
pp. 453-460 ◽  
Author(s):  
Matteo Panizza ◽  
Enrico Garbin ◽  
Maria Rosa Valluzzi ◽  
Claudio Modena
Keyword(s):  
Experimental Tests ◽  
Point Of View ◽  
Shear Tests ◽  
Bond Behaviour ◽  
Lime Mortar ◽  
Glass Composites ◽  
Externally Bonded ◽  
Heritage Buildings ◽  
Natural Stones ◽  
The Impact

Compared to more traditional techniques, the application of Externally Bonded-Fibre Reinforced Polymers (EB-FRP) represents a viable alternative for the strengthening of masonry structures, also in case of Cultural Heritage buildings where strict requirements need to be met, aimed at minimizing the impact of the intervention. Since the FRP-to-masonry bond behaviour strongly affects design and effectiveness of such interventions, several investigations have been carried out in recent years to study this phenomenon, generally based on the longer experience developed for concrete substrates. Mortar joints, which are geometrical and mechanical discontinuities, distinguish and characterize masonry substrates from concrete ones, and therefore deserve a special attention as far as their role in the bond behaviour is not clarified yet. This paper, aimed at giving a contribution also from a methodological point of view, presents the main experimental results of shear tests carried out on glass composites (GFRP) applied to natural calcareous stones (pietra leccese), to lime mortar blocks and to masonry prisms made by coupling stones and lime mortar. Overall 22 shear tests were performed, keeping a bonded length of 200 mm for stones and mortar specimens while it was changed from 65 mm (corresponding to one stone and one mortar joint) to 195 mm (three stones and three mortar joints) in the case of masonry prisms. The effect of the FRP end anchorage on the test development was investigated as well, and results of the experimental tests are herein discussed in detail.

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