scholarly journals Effect of laser beam trajectory on pocket geometry in laser micromachining

2020 ◽  
Vol 10 (1) ◽  
pp. 830-838 ◽  
Author(s):  
Grzegorz Witkowski ◽  
Szymon Tofil ◽  
Krystian Mulczyk
Keyword(s):  
Laser Beam ◽  
Surface Condition ◽  
Experimental Tests ◽  
Laser Micromachining ◽  
Milling Process ◽  
Beam Trajectory ◽  
Laser Milling ◽  
Observation Methods ◽  
The Impact ◽  
Ablative Laser

AbstractThe article presents the problem of planning the laser beam trajectory for the laser micromachining process. The article concerns on the ablative laser micromachining issues. Different effects of laser beam trajectory on pocket geometry in laser micromachining were investigated. The results of experimental tests are presented. Based on the research, potential causes of different effects of the laser beam for various trajectories were formulated. Several different types of trajectories for the assumed shape were developed for the purposes of the research. Laser micromachining was performed with fixed parameters of the laser device using different trajectories. The article indicates the significant impact of the laser beam trajectory on the effect of interaction on matter during the laser milling process, which is not often mentioned in scientific reports. The article presents the basic geometrical measurements indicating the need to determine the leading of the laser beam. Studieswere conducted using the microscopic observation methods and interferometric methods for estimating the surface condition. The article indicates the need for extensive research focusing on the mechanism of the impact of the laser beam scan strategy on the effect on the material during ablative laser machining. The article summarizes the analysis and discussion of research results.

scholarly journals The Idea of Using Bayesian Networks in Forecasting Impact of Traffic-Induced Vibrations Transmitted through the Ground on Residential Buildings

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 339 ◽  
Author(s):  
Agata Siemaszko ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Bayesian Networks ◽  
Residential Buildings ◽  
Surface Condition ◽  
Experimental Tests ◽  
Entropy Method ◽  
Information Value ◽  
Decision Support Model ◽  
The Road ◽  
Specialized Equipment ◽  
The Impact

Traffic–induced vibrations may constitute a considerable load to buildings. In this paper, vibrations transmitted through the ground caused by wheeled vehicles are considered. This phenomenon may cause cracking of plaster, cracks in load-bearing elements or even, in extreme cases, collapse of the whole structure. Measurements of vibrations of real structures are costly and laborious. Therefore, the aim of the present paper is to propose a method of using Bayesian networks combined with implementation of geoscience for assessment of impact of traffic–induced vibrations on residential buildings. Firstly, the experimental tests were performed on different buildings using specialized equipment taking into account five factors: Distance from the building to the edge of the road, condition of road surface, condition of the building, the absorption of soil and the type of vehicle. Then, probabilistic analyses applying Bayesian networks were conducted and two methods of assessing the information value (EVSI method and entropy method) were compared. Finally, the developed diagnostic–decision support model was tested, so as to verify the most important parameter, affecting the possibility of structural vibrations to occur. The results of the study clearly showed that the use of Bayesian networks was a very effective approach to assess the impact of traffic-induced vibrations. The developed algorithm could be successfully applied both to existing and planned buildings, for which the source of vibration is already present or may appear in the future.

Producing Three-Dimensional Shapes by Laser Milling

1990 ◽  
Vol 112 (4) ◽  
pp. 375-379 ◽  
Author(s):  
R. K. C. Hsu ◽  
S. M. Copley
Keyword(s):  
Carbon Dioxide ◽  
Laser Beam ◽  
Carbon Dioxide Laser ◽  
Three Dimensional ◽  
Milling Process ◽  
Model Material ◽  
Layer Plane ◽  
Uniform Thickness ◽  
Laser Milling ◽  
Focused Beam

A laser milling process employing a pulsed, carbon dioxide laser has been investigated using graphite as a model material. Material is removed by scanning the focused beam across the surface of the workpiece leaving behind a series of narrow, parallel, overlapping grooves. These grooves, together, constitute the removal of a thin layer of uniform thickness lying parallel to a layer plane. In order to remove layers bounded at the edge by upright walls perpendicular to the layer plane, the laser beam must be tilted with respect to the layer plane. Using this approach, it is possible to produce perpendicular steps and cylindrical surfaces.

The Impact of Machining Techniques on Centrifugal Compressor Impeller Performance

1997 ◽  
Author(s):  
P. R. N. Childs ◽  
M. B. Noronha
Keyword(s):  
Surface Condition ◽  
Milling Process ◽  
Cnc Milling ◽  
Negative Effects ◽  
Local Flow ◽  
Tool Marks ◽  
Tool Mark ◽  
Cutter Path ◽  
Compressor Performance ◽  
The Impact

A large proportion of modern centrifugal impellers are machined from solid forgings rather than made from cast metal. The CNC milling process offers options to manufacturers to minimise manufacturing costs whilst also enhancing performance of the impeller. Efficient manufacturing can result in cutter tool marks and paths and associated roughness remaining on the hub and blade surfaces of impellers as a result of minimising passes and maximising the cut. The goal of manufacturers is to allow these marks to be as deep as possible to minimise machining costs but without any negative effects in performance and possibly even enhancing it. There are existing modelling methods that predict the influence of roughness on compressor performance using the definition of an equivalent sand grain roughness. The purpose of this study is to relate the performance directly to the tool mark characteristics that are by-products of machining, namely cusp height, cutter path roughness and orientation of the cutter path relative to the local flow velocity, to review the current modelling techniques for predicting the influence of surface condition on compressor performance and to show the scope for optimisation of manufacturing and performance considerations.

1997 John P. Davis Award: The Impact of Machining Techniques on Centrifugal Compressor Impeller Performance

1999 ◽  
Vol 121 (4) ◽  
pp. 637-643 ◽  
Author(s):  
P. R. N. Childs ◽  
M. B. Noronha
Keyword(s):  
Surface Condition ◽  
Milling Process ◽  
Cnc Milling ◽  
Negative Effects ◽  
Local Flow ◽  
Tool Marks ◽  
Tool Mark ◽  
Cutter Path ◽  
Compressor Performance ◽  
The Impact

A large proportion of modern centrifugal impellers are machined from solid forgings rather than made from cast metal. The CNC milling process offers options to manufacturers to minimize manufacturing costs while also enhancing the performance of the impeller. Efficient manufacturing can result in cutter tool marks and paths and associated roughness remaining on the hub and blade surfaces of impellers as a result of minimizing passes and maximizing the cut. The goal of manufacturers is to allow these marks to be as deep as possible to minimize machining costs, but without any negative effects on performance, and possibly even enhancing it. There are existing modeling methods that predict the influence of roughness on compressor performance using the definition of an equivalent sand grain roughness. The purpose of this study is to relate the performance directly to the tool mark characteristics that are by-products of machining, namely cusp height, cutter path roughness, and orientation of the cutter path relative to the local flow velocity, to review the current modeling techniques for predicting the influence of surface condition on compressor performance and to show the scope for optimization of manufacturing and performance considerations.

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 Coir Fibers Treated with Henna as a Potential Reinforcing Filler in the Synthesis of Polyurethane Composites

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1128
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Agnė Kairytė
Keyword(s):  
Mechanical Properties ◽  
High Energy ◽  
Dynamic Mechanical Properties ◽  
Milling Process ◽  
Coir Fiber ◽  
Lawsonia Inermis ◽  
Coir Fibers ◽  
Mechanical Performances ◽  
The Impact ◽  
Reinforcing Filler

In this study, coir fibers were successfully modified with henna (derived from the Lawsonia inermis plant) using a high-energy ball-milling process. In the next step, such developed filler was used as a reinforcing filler in the production of rigid polyurethane (PUR) foams. The impact of 1, 2, and 5 wt % of coir-fiber filler on structural and physico-mechanical properties was evaluated. Among all modified series of PUR composites, the greatest improvement in physico-mechanical performances was observed for PUR composites reinforced with 1 wt % of the coir-fiber filler. For example, on the addition of 1 wt % of coir-fiber filler, the compression strength was improved by 23%, while the flexural strength increased by 9%. Similar dependence was observed in the case of dynamic-mechanical properties—on the addition of 1 wt % of the filler, the value of glass transition temperature increased from 149 °C to 178 °C, while the value of storage modulus increased by ~80%. It was found that PUR composites reinforced with coir-fiber filler were characterized by better mechanical performances after the UV-aging.

scholarly journals The Surface Condition of Ni-Cr after SiC Abrasive Blasting for Applications in Ceramic Restorations

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5824
Author(s):  
Weronika Czepułkowska-Pawlak ◽  
Emilia Wołowiec-Korecka ◽  
Leszek Klimek
Keyword(s):  
Surface Condition ◽  
Abrasive Particle ◽  
Surface Profile ◽  
Abrasive Particles ◽  
Dental Restorations ◽  
Large Width ◽  
Ceramic Restorations ◽  
The Impact ◽  
Abrasive Size ◽  
Abrasive Blasting

Abrasive blasting is a process widely used in dentistry. One of the uses is the development of metal surfaces for connections with ceramics in fixed prosthetic restorations. The purpose of this paper was to check how the rough surface profile (width, height, and depth on unevenness) impacts the surface’s condition, like its wettability and percentage of stuck abrasives. The Ni-Cr alloy surface was abrasive blasted by silicon carbide with the various pressure parameters (0.2, 0.4, and 0.6 MPa) and abrasive particle sizes (50, 110, and 250 µm). Cleaned surfaces were examined for roughness, wettability, and percentage of stuck abrasive particles on the surface. The surface after abrasive blasting using 110 µm of abrasive size and 0.4 MPa pressure has the best wettability results. The width of unevenness may cause it. When the unevenness has too small or too large width and depth, the fluids may not cover the entire cavities because of locking the air. The surface condition of dental alloys directly affects metal–ceramic connection strength. The knowledge about the impact of the abrasive blasting parameters on the bond strength will allow one to create durable dental restorations.

The Impact of Ball Milling Process Parameters on the Preparation of Nano Silicon Powder

2021 ◽  
Vol 217 (1) ◽  
pp. 255-264
Author(s):  
Xiaomeng Zhu ◽  
Xiaolan Cai ◽  
Shuang Zhang ◽  
Lei Wang ◽  
Xudong Cui
Keyword(s):  
Ball Milling ◽  
Process Parameters ◽  
Silicon Powder ◽  
Milling Process ◽  
Ball Milling Process ◽  
Nano Silicon ◽  
The Impact

An Investigation of the Vibration Testing Method for Small Diameter Endmills

2014 ◽  
Vol 625 ◽  
pp. 134-139
Author(s):  
Takenori Ono
Keyword(s):  
Small Diameter ◽  
Milling Process ◽  
Modal Parameters ◽  
Vibration Testing ◽  
Function Generator ◽  
Testing Method ◽  
Milling Tool ◽  
Compliance Curve ◽  
Vibration Tests ◽  
The Impact

This paper introduced about the in-process vibration testing method for small diameter endmill. By this method, the natural frequency and modal parameters such as mass, damping, and stiffness of the milling tool can be determined in the milling process. An oscillation of the vibrator is controlled by the function generator to apply the impact force at the appropriate cutting period. The measurement setup can determine the compliance curve by the measurement signals of the exiting force and tool deformation. To evaluate the feasibility of the new method, vibration tests were performed on a square endmill which has the diameter of 4 mm in the milling on brass material. Results of vibration tests show that modal parameters of the specific vibration mode can be determined by the new developed method.

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