Design And Performance Evaluation Of The Thermal Insulation-regulating Immersion Suit

As the necessary life-saving clothing to protect the Marine operation from cold water,immersion suit can effectively prevent the rapid heat loss,maintain the normal physiological function of the human body,and thus prolong the survival time in cold water.Previous studies on immersion suit is still insufficient,which mainly focused on the waterproof and thermal insulation performance of fabrics and garments.There may be physiological thermal stress while not be immersed,which seriously affects the thermal comfort of suit.Therefore,it is of great significance for the development and performance evaluation of high-performance immersion suit,which can realize thermal insulation adjustion to adapt different working environments.Based on the current research status,the performance requirements of the immersion suit were analyzed,considering the "human-clothing-environment" system.Then,combined with the fabric selection,structure design and ease allowance,an immersion suit.with good thermal comfort and protection was developed.Finally,the ergonomic performance of immersion suit was assessed by subjective and objective experiments.Research findings were as follows:(1)By analyzing the changes of human dimension under typical motions,the movement ease allowance at each part of immersion suit were obtained.Combined with the static ease allowance and design ease allowance,the final ease allowance and size at the key parts of immersion suit were determined after trial and revision.The size of girth for chest,waist and buttocks were 118 cm,104 cm and 114 cm respectively,and the size of length for back,crotch and sub-femoral was 56 cm,32 cm and 102 cm respectively.(2)The immersion suit has a three-layer structure of waterproof layer,adjustable inflatable layer and thermal layer.From the perspective of human ergonomics,the waterproof layer adopted overall structure,with an waterproof zipper.The aramid laminated composite fabric was selected as the waterproof layer fabric,and test indicated that the breaking strength were higher than 500 N in both dry and wet condition,and the hydrostatic pressure resistance was higher than 8000 mmH2O.The inflatable layer is onepiece structure,with an inflatable air tap at the front chest,which can be quickly inflated while being immersed or in an environment at low temperature.The fabric of inflatable layer was an airtight fabric,with numbers of microporous TPU film attached on backside of polyester layer by heat pressing.The structure of the thermal layer is consistent with that of the waterproof layer.The filling materials were Aerogel and Thinsulate.The test indicated that the Aerogel fabrics had better thermal insulation performance under the lower gram weight.(3)The immersion suit with inflatable layer developed in this study can realize the adaptability of clothing thermal performance and provide certain anti-compressive property.The total thermal insulation of the two immersion suits designed in this study were 17.4%and 12.8%higher than that of the immersion suit on the market respectively.With the increase of simulated pressure,the decrement for total thermal insulation and local thermal insulation(except chest)of the three immersion suits were more obvious.Noted that air inflation would be helpful to improve the thermal insulation performance of the immersion suit,and weaken the decrease of thermal insulation caused by pressure to a certain extent.Compared with the un-inflatable state,the total and the local thermal insulation of clothing were generally improved.The increase of thermal insulation of aerogel immersion suit was 7.8%,2.9%and 9.5%respectively under no pressure,low pressure and high pressure;and that of Thinsulate immersion suit could be 12.7%.5.9%and 4.9%respectively.The contribution of the inflation layer to the thermal insulation performance of immersion suit was about one third of that between clothing and human body micro-environment.The total thermal insulation of immersion suit increased with the air inflating volume under pressure.The thermal insulation of inflation state(1/3FULL,2/3FULL,FULL)were significantly higher than that of un-inflation state(CON)(p<0.05),and this trend was more obvious with the increase of pressure.Under high pressure,inflation can increase the thermal insulation by 8%.(4)It was found that the comfort property of immersion suit developed was better than that on the market.The evaluation of the difficulty of wearing and taking off were both above level 3.The wearing and taking off of aerogel immersion suit was relatively easier(p<0.05),which up to level 3.7.The evaluation of motion comfort showed that,in un-inflated condition,the comfort performance of the aerogel immersion suit was higher than that of the immersion suit on the market.The wearing comfort at main parts decreased when the aerogel immersion suit was inflated,However,the evaluations of the motion comfort were more than level 3.1.The subjects’ average satisfaction with the local structure of the aerogel immersion suit was higher than that of the immersion suit on the market.However,the average structural satisfaction of the aerogel immersion suit decreased in inflation condition.The research findings provide constructive reference for the design and development of immersion suit,and also provides an experimental evaluation method for ergonomic performance assessment of immersion suits.