scholarly journals A Charge-Based Mechanistic Study into the Effects of Process Parameters on Fiber Accumulating Geometry for a Melt Electrohydrodynamic Process

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1440
Author(s):  
Kai Cao ◽  
Fucheng Zhang ◽  
Robert C. Chang
Keyword(s):  
Steady State ◽  
Process Parameters ◽  
Process Variable ◽  
Deposition Process ◽  
Mechanistic Study ◽  
Shape Signature ◽  
Unique Shape ◽  
Collector Temperature ◽  
Fiber Deposition ◽  
A Charge

Melt electrohydrodynamic processes, in conjunction with a moveable collector, have promising engineered tissue applications. However, the residual charges within the fibers deteriorate its printing fidelity. To clarify the mechanism through which the residual charges play roles and exclude the confounding effects of collector movement, a stationary printing mode is adopted in which fibers deposit on a stationary collector. Effects of process parameters on generalizable printing outcomes are studied herein. The fiber deposit bears a unique shape signature typified by a central cone surrounded by an outer ring and is characterized by a ratio of its height and base diameter Hdep/Ddep. Results indicate Hdep/Ddep increases with collector temperature and decreases slightly with voltage. Moreover, the steady-state dynamic jet deposition process is recorded and analyzed at different collector temperatures. A charge-based polarization mechanism describing the effect of collector temperature on the fiber accumulating shape is apparent in both initial and steady-state phases of fiber deposition. Therefore, a key outcome of this study is the identification and mechanistic understanding of collector temperature as a tunable process variable that can yield predictable structural outcomes. This may have cross-cutting potential for additive manufacturing process applications such as the melt electrowriting of layered scaffolds.

scholarly journals Analysis of the Process Parameter Influence in Laser Cladding of 316L Stainless Steel

2018 ◽  
Vol 2 (3) ◽  
pp. 55 ◽  
Author(s):  
Piera Alvarez ◽  
M. Montealegre ◽  
Jose Pulido-Jiménez ◽  
Jon Arrizubieta
Keyword(s):  
Stainless Steel ◽  
Laser Cladding ◽  
Process Parameters ◽  
Cross Sections ◽  
316L Stainless Steel ◽  
Deposition Process ◽  
Process Parameter ◽  
Optimum Process ◽  
Processing Times ◽  
Manufacturing Technologies

Laser Cladding is one of the leading processes within Additive Manufacturing technologies, which has concentrated a considerable amount of effort on its development. In regard to the latter, the current study aims to summarize the influence of the most relevant process parameters in the laser cladding processing of single and compound volumes (solid forms) made from AISI 316L stainless steel powders and using a coaxial nozzle for their deposition. Process speed, applied laser power and powder flow are considered to be the main variables affecting the laser cladding in single clads, whereas overlap percentage and overlapping strategy also become relevant when dealing with multiple clads. By setting appropriate values for each process parameter, the main goal of this paper is to develop a processing window in which a good metallurgical bond between the delivered powder and the substrate is obtained, trying simultaneously to maintain processing times at their lowest value possible. Conventional metallography techniques were performed on the cross sections of the laser tracks to measure the effective dimensions of clads, height and width, as well as the resulting dilution value. Besides the influence of the overlap between contiguous clads and layers, physical defects such as porosity and cracks were also evaluated. Optimum process parameters to maximize productivity were defined as 13 mm/s, 2500 W, 30% of overlap and a 25 g/min powder feed rate.

MODELLING COMPACTION BEHAVIOR OF TOUGHENED PREPREG DURING AUTOMATED FIBRE PLACEMENT

2021 ◽  
Author(s):  
SARTHAK MAHAPATRA SARTHAK MAHAPATRA ◽  
JONATHAN BELNOUE ◽  
JAMES KRATZ ◽  
DMITRY S. IVANOV ◽  
STEPHEN R. HALLETT
Keyword(s):  
Process Parameters ◽  
Mechanical Model ◽  
Numerical Models ◽  
Deposition Process ◽  
Roller Compaction ◽  
Manufacturing Processes ◽  
Automated Manufacturing ◽  
Trial And Error ◽  
Compaction Behavior ◽  
Statistical Relationships

One of the most widely used automated manufacturing processes for composite parts is automated fibre placement (AFP). The deposition process involves the simultaneous warming, lay-up and consolidation of prepreg consisting of multitude of process parameters. Currently, AFP process parameters that ensure part conformance are derived by expensive and time-consuming trial-and-error approaches. The aim of this study is to demonstrate how physics-based finite element simulations that can predict the as manufactured geometry of a preform deposited by AFP can help reduce some of the empiricism associated with current industry practices. Here we particularly focus on the consolidation behaviour of toughened prepregs during the deposition process. An isothermal roller compaction model with thermal properties derived from an independent simplified thermo-mechanical model of the AFP head is used. Additionally, a fully characterised viscoelastic material definition is used for the prepreg tape along with a hyperelastic material for the compaction roller to accurately represent the physical parts. Various lay-up speeds, heater powers and compaction forces are simulated. To reduce the empiricism present in the manufacturing process, the viability of incorporating the numerical models into existing statistical relationships between process parameters and manufactured geometry is examined.

Interplay between variable direct current sputtering deposition process parameters and properties of ZnO:Ga thin films

2018 ◽  
Vol 660 ◽  
pp. 538-545 ◽  
Author(s):  
Mohammad Tanvirul Ferdaous ◽  
Seyed Ahmad Shahahmadi ◽  
Megat Mohd Izhar Sapeli ◽  
Puvaneswaran Chelvanathan ◽  
Md. Akhtaruzzaman ◽  
...  
Keyword(s):  
Thin Films ◽  
Process Parameters ◽  
Direct Current ◽  
Deposition Process ◽  
Sputtering Deposition ◽  
Direct Current Sputtering

Effects of Laser Melting Deposition Process Parameters on Ultrasonic Testing Accuracy of TA15 Titanium Alloy

2019 ◽  
Vol 39 (10) ◽  
pp. 1014002
Author(s):  
孙长进 Sun Changjin ◽  
赵吉宾 Zhao Jibin ◽  
赵宇辉 Zhao Yuhui ◽  
何振丰 He Zhenfeng ◽  
王志国 Wang Zhiguo ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Process Parameters ◽  
Ultrasonic Testing ◽  
Deposition Process ◽  
Laser Melting ◽  
Ta15 Titanium Alloy ◽  
Testing Accuracy ◽  
Laser Melting Deposition

Optimisation of process parameters for deposition of colmonoy using directed energy deposition process

2020 ◽  
Vol 26 ◽  
pp. 1108-1112 ◽  
Author(s):  
B.N. Manjunath ◽  
A.R. Vinod ◽  
K. Abhinav ◽  
S.K. Verma ◽  
M. Ravi Sankar
Keyword(s):  
Process Parameters ◽  
Energy Deposition ◽  
Deposition Process ◽  
Directed Energy Deposition ◽  
Directed Energy

scholarly journals Cardiodynamic Interactions between Two S1P1 Receptor Modulators in an Experimental Clinical Setting: Different Pharmacokinetic Properties as an Opportunity to Mitigate First-Dose Heart Rate Effects

2019 ◽  
Vol 20 (13) ◽  
pp. 3232 ◽  
Author(s):  
Pierre-Eric Juif ◽  
Mike Ufer ◽  
Jasper Dingemanse
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Dose Effect ◽  
Mechanistic Study ◽  
Rate Effects ◽  
Pharmacokinetic Properties ◽  
Sphingosine 1 Phosphate ◽  
Chronotropic Effects ◽  
Therapeutic Doses ◽  
Electrocardiogram Ecg

A decrease in heart rate (HR) is a well-established first-dose effect of sphingosine-1-phosphate subtype 1 receptor (S1P1R) modulators. For compounds with a short half-life (t1/2), this can be mitigated by gradual up-titration to therapeutic doses, whereas this is not required for compounds with a long t1/2 due to the less pronounced first-dose-related negative chronotropic effects. Based on this conceptual framework, this mechanistic study investigated whether first-dose HR effects of ponesimod (t1/2 ~32 h) can be mitigated by prior administration of cenerimod (t1/2 ~415 h). Healthy subjects (n = 12) were randomly assigned to active or placebo (2:1 ratio). Active treatment consisted of a single dose of 10 mg ponesimod on Day 1, 18, and 37 and multiple-dose administration of 2 mg once daily cenerimod (Day 9–36). Placebos of cenerimod and ponesimod were used as reference treatment. Cardiodynamic parameters were derived from 24 h Holter electrocardiogram (ECG) assessments on Day 1, 9, 10, 18, 36, and 37. Ponesimod (10 mg) alone triggered a transient mean decrease from baseline in hourly mean HR of 17 bpm. In contrast, decreases of 5.0 and 4.8 bpm were observed when ponesimod was given at near half steady-state (Day 18) or steady-state (Day 37) cenerimod, respectively. Hourly mean HR decreased after first administration of cenerimod and placebo was 7.4 and 4.0 bpm, respectively. Treatment with ponesimod and cenerimod alone or in combination was safe and tolerated. First-dose-related negative chronotropic effects of ponesimod were less pronounced when administered after initiation of cenerimod suggesting mitigation of this class-related liability.

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