Insights into Partial Slips and Temperature Jumps of a Nanofluid Flow over a Stretched or Shrinking Surface

Raso

Textile Research Journal

et al. 2022

The aim of this work was to develop and characterize polyurethane-based shape memory polymer filament yarns of a suitable diameter and thermo-mechanical performance for use in tailored multi-sectorial applications. Different polymer compositions – pure shape memory polyurethane and shape memory polyurethane composites with 0.3 and 0.5 wt.% of multi-walled carbon nanotubes or carbon black as additives – were studied. Filaments were obtained using a melt spinning process that allowed the production of the permanent and temporary shape of the shape memory polyurethane filament. Two drawing speeds (20 and 32 m/min) were studied. Characterization techniques such as the tensile test, differential scanning calorimetry, and dynamic mechanical analysis were used to investigate the shape-memory effect of the filaments. Pure and additive shape memory polyurethane filament yarns of a controlled diameter were produced. The results indicated that the pure shape memory polyurethane on the temporary shape had the highest tensile strength (234 MPa). Filaments with carbon black revealed a significant strain (335%) in the permanent shape with respect to the other filaments. The melt spinning process influenced the soft segment glass transition temperature (Tgs) significantly, with a decrease in the temporary shape (first heating) as compared to the permanent shape (second and third heating). However, only the 0.5% multi-walled carbon nanotubes additive clearly influenced the filament, increasing the Tgs by 10°C. The additives also influenced the shape-memory effect, obtaining an increased fixity ratio (up to 97%) with the multi-walled carbon nanotubes additive and an increased recovery ratio (up to 86%) with the carbon black additive.

“…The enthalpy of the peak decreased on the second and third cycle, probably due to the fast crystallization process that did not permit the full reordering of this phase. 51–54…”

Section: Resultsmentioning

confidence: 99%

Polyurethane shape memory filament yarns: Melt spinning, carbon-based reinforcement, and characterization

Raso

Textile Research Journal

et al. 2022

Journal of Low Frequency Noise, Vibration and Active Control

“…Then, the temperature control-monitoring system was turned on to heat or cool the reverberation field until the target temperature T was achieved. To mitigate the effects of temperature shock 35 and instability, 36 temperature sensors were arranged on both surfaces of the panel. After temperatures ( T i , T 0 ) on both surfaces were consistent with T (Ti≈T, To≈T), keep the temperature for a while (>0.5 h) to meet the experiment state.…”

Section: A Brief Statement Of the Improved Sound Transmission Loss Ex...mentioning

confidence: 99%

Analysis of sound transmission loss characteristics of aircraft composite panel under variable temperature environment

Peng

Dong

Yan

2022

An improved sound transmission loss (STL) experimental technique based on the sound pressure method (SPM) and acoustic box method is proposed to investigate the temperature influence on the STL of the ribbed carbon fiber reinforced plastics aircraft panel. SPM principle is given. The measurement procedure of the improved STL technique is presented and its reliability is verified. STL variable characteristics of the panel within −40°C–40°C were measured. Results showed that temperature had a significant effect on the panel’s STL. The overall STL varied nonlinearly with temperature, whereas STL exhibited a fluctuation or monotony trend at a single center frequency. Temperature variation caused changes of STL peak/dip frequencies and redistribution of stiffness-controlled, resonance-controlled, coincidence-controlled, and damping-controlled regions. The causes of the aforementioned are given. This study reveals the relationship between temperature, thermomechanical parameters and STL. The findings have applications in the design, measurement, analysis, and theoretical development of composite structure acoustics.

“…He and Abd Elazem [23] investigated the impact of partial slips and temperature jumps on heat and mass transport in a boundary layer nanofluid flowing over a stretched or shrinking surface.…”

Section: Introductionmentioning

confidence: 99%

“…The findings have a wide range of applications, including thermal-mechanical effects in high-speed flights, rockets, nuclear reactors and design of a solar energy collector's heat transfer in Refs. [23,[30][31].…”

Section: Introductionmentioning

confidence: 99%

The Carbon Nanotube-Embedded Boundary Layer Theory for Energy Harvesting

He¹,

Elazem

2022

FU Mech Eng

Self Cite

Single-walled carbon nanotubes (SWNTs) and multi-walled nanotubes (MWNTs) are gaining appeal in mechanical engineering and industrial applications due to their direct influence on enhancing the thermal conductivity of base fluids. With such intriguing properties of carbon nanotubes in mind, our goal in this work is to investigate radiation effects on the flow of carbon nanotube suspended nanofluids in the presence of a magnetic field past a stretched sheet impacted by slip state. CNTs flow and heat transmission are frequently modelled in practice using nonlinear differential equation systems. This system has been precisely solved, and an accurate analytical expression for the fluid velocity in terms of an exponential function has been derived, while the temperature distribution is stated in terms of a confluent hypergeometric function. The impact of the radiation parameter, slip parameter, sloid volume fraction, magnetic parameter, Eckart and Prandtl numbers on the velocity, temperature, and heat transfer rate profiles are demonstrated using a parametric analysis. When compared to the two types of nanoparticles (Cooper and Silver) in earlier published articles, temperature profiles for single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs) are revealed to be particularly sensitive to radiation, solid volume fraction, and slip parameters. Nanomechanical gears, nanosensors, nanocomposite materials, resonators, and thermal materials are only a few of the present problem's technical applications.