scholarly journals On the Improvement of Thermal Protection for Temperature-Responsive Protective Clothing Incorporated with Shape Memory Alloy

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1932 ◽  
Author(s):  
Jiazhen He ◽  
Yehu Lu ◽  
Lijun Wang ◽  
Nini Ma
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Protective Clothing ◽  
Thermal Protection ◽  
Thermal Environment ◽  
Heat Exposure ◽  
Air Gap ◽  
Suitable Material ◽  
Sma Spring ◽  
Protective Performance

This study explored the application of shape memory alloy (SMA) springs in a multilayer protective fabric assembly for intelligent insulation that responded to thermal environment changes. Once the SMA spring was actuated, clothing layers were separated, creating an adjustable air gap between the adjacent fabric layers. The impacts of six different SMA arrangement modes and two different spring sizes on thermal protection against either a radiant heat exposure (12 kW/m2) or a hot surface exposure (400 °C) were investigated. The findings showed that the incorporation of SMA springs into the fabric assembly improved the thermal protection, but the extent to which the springs provided thermal protection was dependent on the arrangement mode and spring size. The effectiveness of reinforcing the protective performance using SMA springs depended on the ability of clothing layers to expand an air layer. The regression models were established to quantitatively assess the relationship between the air gap formed by SMA spring and the thermal protective performance of clothing. This study demonstrated the potential of SMA spring as a suitable material for the development of intelligent garments to provide additional thermal protection and thus reduce the number of clothing layers for transitional thermal protective clothing.

On the Effectiveness of Temperature-Responsive Protective Fabric Incorporated With Shape Memory Alloy (SMA) Under Radiant Heat Exposure

2019 ◽  
Vol 38 (3) ◽  
pp. 212-224 ◽  
Author(s):  
Lijun Wang ◽  
Yehu Lu ◽  
Jiazhen He
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Protective Clothing ◽  
Thermal Protection ◽  
Heat Exposure ◽  
Radiant Heat ◽  
Air Gap ◽  
Environment Change ◽  
Temperature Responsive ◽  
Thermal Insulating

To improve thermal protection of protective clothing, temperature-responsive protective fabrics incorporated with shape memory alloy (SMA) springs varying on four different deformation heights and five types arrangement modes were designed. The thermal protection was investigated under radiant heat exposure of 0.39 cal/cm2 s. The results indicated that the air gap between fabric layers produced by SMA springs effectively improved protective performance. The thermal protection of fabrics with different SAM arrangement modes and sizes showed different trends, and the interaction effects of arrangement mode and size were analyzed. Moreover, the optimized arrangement and size of SMA springs were suggested. The regression models were established to assess the relationship between the air gap and thermal protection. This study demonstrated that the combination of flame-resistant fabric with SMA was feasible to develop temperature-responsive protective clothing because it could improve thermal insulating property by producing intelligent air gaps that responded to environment change.

Investigation of the Thermal Protective Performance of Shape Memory Fabric System: Effect of Moisture and Position of Shape Memory Alloy

2020 ◽  
pp. 0887302X2093707
Author(s):  
Yehu Lu ◽  
Lijun Wang ◽  
Jiazhen He ◽  
Pengjun Xu ◽  
Wenfang Song
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Protection ◽  
System Effect ◽  
Thermal Protective Performance ◽  
Temperature Responsive ◽  
Effect Of Moisture ◽  
Fabric System ◽  
Sma Spring ◽  
Protective Performance

A prototype of temperature-responsive protective fabric assembly with shape memory alloy (SMA) spring was developed. The effect of moisture on the thermal protective performance of fabric was investigated under radiant heat exposure and hot surface contact. The thermal liner of fabric system was pretreated with moisture amount of 25%, 50%, and 100%. Meanwhile, the thermal protection of fabric assembly with SMA springs in different positions between the fabric layers was explored. The results showed that moisture above 25% had a positive influence on thermal protective performance of both traditional and SMA fabric assembly under two hazardous environments. The effect of moisture in SMA fabric assembly was more remarkable than that in fabric without spring. And the SMA spring located between thermal liner and moisture barrier provided better thermal protective performance. The research findings will be beneficial for manufacturing high-performance temperature-responsive fabric.

scholarly journals Thermal Protective Performance of Firefighters’ Clothing Under Low-Intensity Radiation Heat Exposure

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hualing He ◽  
Zhicai Yu ◽  
Chunbo Zhang ◽  
Minhua Li
Keyword(s):  
Protective Clothing ◽  
Thermal Protection ◽  
Heat Exposure ◽  
Test Methods ◽  
Stored Energy ◽  
Radiation Heat ◽  
Low Intensity ◽  
Fabric System ◽  
Protective Performance ◽  
Intensity Radiation

AbstractThe stored energy provided by the fabric assemblies will greatly influence the thermal protection performance (TPP) of firefighters’ protective clothing under low-intensity radiation heat exposure. In this study, two test methods, namely radiant protective performance (RPP) and stored energy test (SET), were used to investigate the TPP of the fabric assemblies. The results indicated that TSET value was lower than TRPP value because of the release of the stored energy in the fabric assemblies after heat exposure. Increasing the fabric layer numbers, air gap between the fabric assemblies would increase the time of TRPP and TSET, indicating that the thermal stored energy weakened the TPP of the firefighters’ protective clothing. Moreover, the TRPP and TSET of the fabric system would be increased when the moisture barrier was cut in the fabric combination system. These findings suggested that stored energy should be considered in analyzing the TPP of fabric assemblies..

Experimental study of heat and moisture transfer in vertical air gap under protective clothing against dry and wet heat exposures

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yun Su ◽  
Miao Tian ◽  
Yunyi Wang ◽  
Xianghui Zhang ◽  
Jun Li
Keyword(s):  
Natural Convection ◽  
Protective Clothing ◽  
Moisture Transfer ◽  
Heat Exposure ◽  
Air Gap ◽  
Gap Size ◽  
Heat And Moisture Transfer ◽  
Content Type ◽  
Wet Heat ◽  
Heat And Moisture

PurposeThe purpose of this paper is to study heat and steam transfer in a vertical air gap and improve thermal protective performance of protective clothing under thermal radiation and hot steam.Design/methodology/approachAn experiment-based model was introduced to analyze heat and moisture transfer in the vertical air gap between the protective clothing and human body. A developed test apparatus was used to simulate different air gap sizes (3, 6, 9, 12, 15, 18, 21 and 24 mm). The protective clothing with different air gap sizes was subjected to dry and wet heat exposures.FindingsThe increase of the air gap size reduced the heat and moisture transfer from the protective clothing to the skin surface under both heat exposures. The minimum air gap size for the initiation of natural convection in the dry heat exposure was between 6 and 9 mm, while the air gap size for the occurrence of natural convection was increased in the wet heat exposure. In addition, the steam mass flux presented a sharp decrease with the rising of the air gap size, followed by a stable state, mainly depending on the molecular diffusion and the convection mass transfer.Originality/valueThis research provides a better understanding of the optimum air gap under the protective clothing, which contributes to the design of optimum air gap size that provided higher thermal protection against dry and wet heat exposures.

scholarly journals Development of Subcarangiform Bionic Robotic Fish Propelled by Shape Memory Alloy Actuators

2021 ◽  
Vol 71 (1) ◽  
pp. 94-101
Author(s):  
M. Muralidharan ◽  
I.A. Palani
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Kinematic Model ◽  
Open Loop ◽  
Robotic Fish ◽  
Water Medium ◽  
Light Weight ◽  
Caudal Fin ◽  
Locomotion Pattern ◽  
Sma Spring

In this paper, a shape memory alloy (SMA) actuated subcarangiform robotic fish has been demonstrated using a spring based propulsion mechanism. The bionic robotic fish developed using SMA spring actuators and light weight 3D printed components can be employed for under water applications. The proposed SMA spring-based design without conventional motor and other rotary actuators was able to achieve two-way shape memory effect and has reproduced the subcarangiform locomotion pattern. The positional kinematic model has been developed and the dynamics of the proposed mechanism were analysed and simulated using Automated Dynamic Analysis of Mechanical Systems (ADAMS). An open loop Arduino-relay based switching control has been adopted to control the periodic actuation of the SMA spring mechanism. The undulation of caudal fin in air and water medium has been analysed. The caudal fin and posterior body of the developed fish prototype have taken part in undulation resembling subcarangiform locomotion pattern and steady swimming was achieved in water with a forward velocity of 24.5 mm/s. The proposed design is scalable, light weight and cost effective which may be suitable for underwater surveillance application.

Design of a 2 DOF Shape Memory Alloy Actuator Using SMA Springs

2021 ◽  
Author(s):  
Hussein F. M. Ali ◽  
Youngshik Kim
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Open Loop ◽  
Degree Of Freedom ◽  
Biologically Inspired ◽  
Loop Control ◽  
Actuator System ◽  
Sma Actuator ◽  
Sma Spring ◽  
Two Degree Of Freedom

Abstract In this paper, we developed two degree of freedom shape memory alloy (SMA) actuator using SMA springs. This module can be applied easily to various applications: device holder, artificial finger, grippes, fish robot, and many other biologically inspired applications, where small size and small wight of the actuator are very critical. This actuator is composed of two sets of SMA springs: one set is for the rotation around the X axis (roll angle) and the other set is for the rotation around the Y axis (pitch angle). Each set contains two elements: one SMA spring and one antagonistic SMA spring. We used an inertia sensor (IMU) and two potentiometers for angles feedback. The SMA actuator system is modeled mathematically and then tested experimentally in open-loop and closed-loop control. We designed and experimentally tuned a proportional integrator derivative (PID) controller to follow the set points and to track the desired trajectories. The main goal of the presented controller is to control roll and pitch angles simultaneously in order to satisfy set points and trajectories within the work space. The experimental results show that the two degree of freedom SMA actuator system follows the desired setpoints with acceptable rise time and overshoot.

Design, Simulation and Testing of Shape Memory Alloy Actuator for Mixing Two Solutions in High-Pressure Optical Cell for Biophysical Studies

2006 ◽  
Author(s):  
Hongchun Xie ◽  
Jack Zhou ◽  
Parkson Chong
Keyword(s):  
High Pressure ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Intensity Change ◽  
Optical Cell ◽  
Pull Out ◽  
Spring Force ◽  
Heat Response ◽  
Sma Spring

Window-type high-pressure optical cells (HPOC) such as the one designed by Paladini and Weber [Rev. Sci. Instrum. 52, (1981) p. 419] have provided biophysicists a powerful tool to understand the structure-function relationships of biological molecules. However, the conventional HPOC is only good for single solution testing and does not allow for quick mixing and stirring of additional components while the sample is under pressure. To mix two solutions under pressure, Zhou et al [Rev. Sci. Instrum. 69, (1998) p. 3958] developed a laser activated dual chamber HPOC. However, the expensive laser device and its unavailability in most laboratories make the application difficult. In a later study, Zhou et al. [Rev. Sci. Instrum. 71, (2000) p. 4249] introduced shape memory alloy (SMA) as an actuator to unplug a urethane stopper with a biasing spring for agitation. The drawback is that the biasing spring blocks the observing light beam and creates unwanted reflections. This research is to construct an actuator with concentric SMA spring and compressive biasing spring: an SMA helical tensile spring to pull out the stopper to let two solutions mix; and a helical compressive spring to bias and to agitate solutions, and to leave the lower half cuvette clear for optical observation. Due to the limited space in the cuvette, the alignment of two springs is critical for both motion and heat response to activate each spring separately. This paper discusses the design of SMA actuator, SMA spring testing and mixing testing by the SMA spring actuator. Since SMA (nickel-titanium) spring is not solderable and crimping method is limited due to the space, a conductive adhesive is used not only to fix the alignment between springs and cap, but also to conduct electric current. Spring force testing was done by INSTRON. Mixing testing used flourescein intensity change to trace the mixing process. The bio-compatibility of the nickel-titanium SMA with proteins and phospholipids has also been tested.

Thermo-Mechanical Modeling of a Shape Memory Alloy Heat Engine

2011 ◽  
Author(s):  
Christopher B. Churchill ◽  
John Shaw
Keyword(s):  
Heat Transfer ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Heat Engine ◽  
The United States ◽  
Thermodynamic Efficiency ◽  
Low Grade ◽  
Heat Engines ◽  
Deformation Mechanics ◽  
Sma Spring

Two thirds of the energy generated in the United States is currently lost as waste heat, representing a potentially vast source of green energy. Low Carnot efficiency is an inherent limitation of extracting energy from low-grade thermal sources (temperature gradients near or below 100C), and SMA heat engines could be useful for those applications where low weight and packaging are overriding considerations. Although many shape memory alloy (SMA) heat engines have been proposed to harvest this energy, and a few have been built and demonstrated in past decades, they have not been commercially successful. Some of the barriers to commercialization include their perceived low thermodynamic efficiency, high material cost, low material durability, complexities when using fluid baths, and the lack of robust constitutive models and design tools. Recent advances, however, in SMA longevity, reductions in materials costs (as production volumes have increased), and a better understanding of SMA behavior have stimulated new research on SMA heat engines. The Lightweight Thermal Energy Recovery System (LighTERS) is an ongoing ARPA-E funded collaboration between General Motors, HRL Laboratories, Dynalloy, Inc., and the University of Michigan. In the LighTERS engine (a refinement of the Dr. Johnson engine), a closed loop SMA spring element generates mechanical power by pulling itself between alternating hot and cold air regions. The first known thermo-mechanical model for this type of heat engine was developed in three stages. First, the constitutive and heat transfer relationships of an SMA spring form were characterized experimentally. Second, those relationships were used as inputs in a steady-state model of the heat engine, including both convective heat transfer and large-deformation mechanics. Finally, the model was validated successfully against measurements of a experimental heat engine built at HRL Labs.

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