| Enhancing individual thermal protection is one of the major concerns of clothing functional property research The thermal protective property of clothing depends not only on the fiber material and the fabric structure but also on the garment construction and the way of dressing.Objective and quantitative evaluation of clothing thermal protective property should be based on the simulation of human in actual thermal environment as realistic as possible.For this goal,the thermal protective property of both flame resistant fabric and clothing as a whole was thoroughly studied in this paper.First from the fabric level,by improving the existing bench-scale thermal protective performance(TPP)evaluation devices,the fabric itself as well as the influence of air gap size under clothing,the micro-space humidity,moisture and fabric tensile deformation and other factors on the TPP was researched;and further from the overall garment thermal protective property level,a new type flame testing manikin system was researched and developed based on which the air gap under clothing with different dressing poses and garment specifications was objectively characterized and measured,the skin burn model predictions and evaluation of different exposure time,clothing specifications,fabric characteristics,dressing poses,and other factors was investigated.Specific research contents are as follows:1)Bench-scale test of thermal protective fabric under flash fireAs the basis of garment constitute,the TPP of fabric is of great importance.The test result of nine kinds of thermal protective fabric showed that fiber material significantly affects the TPP of fabric,the better the heat resistant and flame retardant property of fiber material,the better the TPP of the fabric;and under same conditions,the heavier the fabric,the better the TPP of it.By developing clothing micro-space simulation equipment,the effect of air gapsize,humidity and moisture under clothing micro-space on TPP was comprehensively studied.Two typical kinds of thermal protective fabric of Nomex(?)?A were chosen as the test samples.Air gaps from 0 to 24 mm were employed.The test result showed that under 35% RH,the TPP of fabric increased rapidly with the increase of air gap at first,then the increment became a little lower with the air gap between 9-15 mm,and subsequently the TPP increased obviously again.With the RH increasing from 35% to65%,95%,the TPP increased correspondingly.It increased sharply with the air gap fiom 3mm to 12 mm,but showed complex changes if the air gap kept increasing.So the air gap of 12 mm was a critical size.In addition,the influence of moisture on the fabric TPP showed that the TPP increased with the moisture increase: with the air gap increasing from 0~12mm,the TPP increased gradually first and then quickly;When the air gap was more than 15 mm,the TPP of fabric with different moisture content showed a complex change.Through the development of fabric tensile deformation evaluation device,the tensile deformation characteristics of fabric under fixed-length was studied.The result showed that the fabric permeability decreased with the increase of tensile extent;under flash fire condition,the TPP value decreased with the tensile deformation when there was no air gap between the fabric and heat flux sensor and increased with the tensile deformation when there existed 6mm air gap.2)Research and development of an advanced flame manikin.The flame manikin system consists of the manikin body,information collection and transmission systems,flame production and gas transmission system,combustion laboratory and supporting facilities,overall monitoring and control system,burn evaluation software platform,which is a comprehensive intersection of multidisciplinary such as biological physics,new materials,advanced manufacturing,ergonomics,combustion engineering,information and automatic control.The body of the flame manikin is flame-retardant and durable which can meet the need of long time testing under high temperature.The size and specifications of the manikin is in line with the body type of Chinese and could cover the body type and size of majority people.With the joint adjustable function and rotation function,burns of different bodv noses in a variety of fire conditions can be simulated.The measuring range,minimum response time,data acquisition interval and the number of the sensor on manikin surface all meet the technical index of relative standard and can be used for helmets,gloves and fire boots evaluation;flameproduction and gas transmission and distribution system can provide 20 s combustion with 84kW/m2 uniformly distributed heat flux which can meet longer burn time;the wall structure,the effective area,ventilation,lighting and other systems of the flame chamber all meet the relevant technical standards;and equipped with adequate safety devices such as monitoring,alerts,automated processing function which can ensure the security of the operator and the test system;the software platform consisted of multiple subsystems such as combustion test subsystem,sensor calibration subsystem,warm-up test subsystem,non-flame real-time test subsystem;the data processing module can provide the temperature change and heat flux change as well as the gas pressure,temperature and humidity,ventilation and other information and can output the burn area,burn degree of skin and total calories absorption and a series of images and reports based on the skin heat transfer and burn integral mode.3)Objective characterization and measurement of air gap under clothing.The size and distribution of air gap under clothing has significant influence on the heat exchange between the inside and the outside of clothing.Typical thermal protective fabric was chose to make several thermal protective clothing specimens.Non-contact 3D scanning systems and 3D reverse engineering software was used to construct the 3D model of naked manikin and dressed manikin.The air gap was characterized by superimposing the two models.With the chromatographic analysis method,the air gap size of each sensor location was measured fast and accurately.The air gap under three specimens with different specifications and dressing poses such as crouching and running was investigated.The result showed that the air gap was not evenly distributed over the human body where the air gap of chest and back parts was relatively small while the legs and arm parts was relatively large.The more fit the clothing,the smaller of the air gap size.In addition,the dressing pose changes would also affect the air gap: the increase of pose range would decrease the total air gap size;smaller change was observed in the chest and back and larger change was observed in the legs and arm parts with posture change.4)Evaluation of thermal protective performance of clothing based on flame manikin.Based on the flame testing manikin system,the skin burn prediction of 10 sets of thermal protective clothing were studied from the aspects of heat source,exposure time,clothing specification,fabric characteristics,dressing posture.The result showed that the flame manikin could not only evaluate the TPP of fiber material and fabric,but also the overall thermal protective clothing.Besides,it could also be used to study other combustion characters such as the time of after flame,shrinkage,fabric fading,carbonization and smoke production,and so on,providing a comprehensive reflection of the garment TPP as a whole.Clothing heat shrinkage study result showed that the heat deformation increased with the rise of thermal environment temperature,decreased with the increase of the fabric density,air gap size under clothing and the range of motion.The heat shrink deformation of clothing was a result of combined effect of heat source conditions,fabric property,garment structure,dressing poses and so on.The skin burn prediction result showed that clothing thermal protective performance decreased rapidly with the increase of the exposure time,the longer of the exposure time the larger the second,third degree burn area;garment fabric characteristics would affect the skin burn area and degree,the heavier the fabric gram weight,the smaller the burn area;the thermal protective performance of garment would be improved by the increase of the garment tolerance,while too large tolerance was not beneficial for the continued increase of thermal protective;bending knees,crouching and running would increase the skin burn area compared with the upright posture,that was,the increase of the motion range would decrease the garment thermal protective performance. |
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