Analysis on the Research Status of Warm Dummy at Home and AbroadRelease time: 2015-06-27 09:49
The development of the thermal dummy can be divided into three phases. In 1941, a scholar from the John Pierce Laboratory at Yale University in the United States and others published a paper in the American Science Journal, which proposed the definition of the Crowe value, that is, a quiet sitting Or people who are engaged in light mental labor (metabolism heat production is 209.2 KJ / m2h), when they feel comfortable in an environment with a room temperature of 21 ° C, a relative humidity of less than 50%, and a wind speed of not more than 0.1 m / S, The thermal resistance of the garments worn is 1 crore. This unit combines human physiological parameters, psychological feelings and environmental conditions, and can be understood and accepted by non-professionals. The U.S. Quartermaster Climatology Institute developed the first-generation warm-body dummy on this basis. Because the warm dummy is a single-segment dummy system, it cannot reflect the temperature distribution of the human body, and can only be used for the general test of clothing thermal resistance, and the static clothing thermal resistance value is obtained. In the 1960s, a second generation of warm body dummy was developed, that is, a multi-stage warm body dummy. The body surface temperature and heating system of each segment are individually controlled, and the dummy body can simulate different postures of the human body and do some simple actions to perform static and dynamic tests of clothing thermal resistance. The third-generation warm manikin can simulate human sweating and can perform more complex movements. It can more realistically and comprehensively reflect the heat and humidity exchange process of the human body, clothing and the environment, and can make heat and humidity transfer performance of clothing. Overview. In the 1970s, the sweat permeability of military uniforms was studied using sweating coppers. The sweating warm dummy was also used to study the thermal performance of civilian clothing. To date, more than 100 manikins have been developed worldwide. The types are: dry and warm body dummy, sweaty body dummy, breathing warm body dummy, immersable warm body dummy, numerical warm body dummy, small warm body dummy, warm body dummy and head.
Dry and warm manikins can work in three ways: variable temperature, constant heat and constant temperature. The temperature change state is based on the human body's thermal regulation model in a cold environment. It simulates the skin temperature change process of a real human group under different environmental conditions. It is a natural balance process. Therefore, the temperature change state has the significance of real human physiological evaluation. The constant heat state is used to observe the differences in the heat dissipation conditions of various parts of the body. It is based on the thermal resistance and environmental parameters of the clothing to use the set heat flow value to observe the differences in heat dissipation of various parts of the body. The constant temperature state is to control the body surface temperature of each anatomical section of the warm dummy in a set range, so that the warm dummy enters a dynamic thermal equilibrium state. This method is used to measure the thermal resistance of clothing. According to the movement mode of the dry heat dummy, it can be divided into static warm dummy and dynamic warm dummy. There are two types of static warming dummy: standing posture and sitting posture. The standing warming dummy is mainly used for clothing warming. The evaluation is that the sitting warming dummy is mainly used in the thermal environment of motor vehicles and The thermal comfort evaluation of motor vehicle drivers is also used for the functional evaluation of space suits. The dynamic warming dummy's active parts vary from country to country, but mainly the shoulder, elbow, knee and ankle joints can be moved to simulate human walking. Dynamic warming dummy is used to study the effects of human movement and wind speed on the warmth of clothing. Dry heat warm body dummy is mainly used to test the heat transfer performance of clothing under dry heat state. According to the basic principle of measuring the thermal resistance of clothing in a constant temperature state, the dummy is placed in an artificial climate chamber, the dummy body is heated with a certain power, and the surface temperature is stabilized at about 33 ° C by the host computer. According to The difference between its surface temperature and ambient temperature and its heating power calculate the thermal resistance of the garment.
Because the dry heat and warm body dummy can only simulate the physiological reaction of the human body (such as skin temperature, heat emission, etc.) in the non-evaporative heat dissipation range, under the thermal environment and sports conditions, the human body mainly relies on evaporative heat dissipation to maintain thermal balance. Research on the heat-moisture transfer mechanism of clothing and comprehensive evaluation of the heat-moisture transfer performance of clothing. Since 1988, scholars have started research on sweating and warming dummy. It is covered with a layer of simulated skin on the surface of the warm dummy, and then somehow simulates human sweating. The main methods for simulating sweating are: ① external water spray method. Spray the distilled water on the surface of the dummy to simulate skin sweating, then put on clothes to increase the average skin temperature to a certain level, and complete all the tests before the parts begin to dry and the skin temperature rises. This quasi-steady state process is very short and difficult to define clearly, and it is impossible to satisfactorily and reproducibly measure evaporation resistance and moisture permeability index; ② internal water supply method. This method is to install a water supply and control device inside the dummy's body, so that the dummy's skin surface is kept moist throughout the test process, which can simulate the state of human sweating. It is mainly used in cold or comfortable environments for occupational protective clothing. Heat and moisture transfer performance was tested.
Breathable warm manikins are mainly used for indoor work environment research and indoor air quality assessment. The basic structure of the respirable warm dummy is the same as that of the warm dummy. It also has heating and temperature control devices. In addition, it also contains an artificial lung, which is composed of a cylinder equipped with a piston. The piston is driven by an electric motor. The number of breaths per minute and lung ventilation (liters) can be controlled. The size and shape of the mouth or nose have an impact on the test results.
The immersable water heating dummy is based on the warm body dummy, and a waterproof sealing device is added to make the dummy waterproof. It is mainly used to test the protective function pll of wetsuits and water life jackets in cold environments. During the test, the dressing dummy was immersed in water, maintaining a constant water temperature, recording the surface temperature of the dummy's skin, the ambient temperature, and the heating power of each section, and calculating the total thermal resistance of the diving suit. Experiments have proved that turbulence can greatly reduce the total thermal resistance of wetsuits, and the height of water waves can also reduce the total thermal resistance of wetsuits [32-33]. The thermal resistance value measured by the immersion heating dummy can also be used to predict the endurance time of the garment in a certain environment.
The numerical warm manikin is an ergonomic study using a "virtual" dummy on a computer. As Computational Fluid Dynamics (CFD) technology is increasingly used in various industries, it is also possible to use computer technology to simulate the human body. In contrast to traditional warm-body dummy, numerical warm-body dummy is a simulation of heat and mass transfer around the dummy by solving a series of partial differential equations.
If you enter specific environmental parameters and the thermal performance of your clothing, the Numeric Manikin can calculate all heat dissipation, such as conduction, convection, radiation, and evaporation, in order to evaluate the thermal comfort and air quality of a certain environment.
The small warm dummy is lying flat in the incubator. The test method is the same as the large warm dummy. It generally consists of 6 heating sections, namely the head, left upper limb, right upper limb, trunk, left lower limb, and right lower limb. Because the ratio of the baby's mass to the body surface area is larger than that of an adult, the dry heat dissipation of a small warm dummy is larger than that of a large warm dummy. The evaluation index of thermal resistance is not much different from that of a large warm dummy. Small warm prostheses are mainly used to evaluate the thermal environment of newborns, especially low-weight infants.
Warm body prosthetic head, prosthetic hand '421, prosthetic foot, etc. are mainly used for the evaluation of helmets or headwear, gloves, shoes and product development. The prosthetic head consists of the skull, face and neck. The three parts are individually heated and controlled independently. The dummy can work in constant temperature and constant heat mode. The test results indicate the thermal comfort of the helmet by the degree of facial temperature drop. Warm body prosthetic hand consists of eight pieces: thumb, index finger, middle finger, ring finger, pinky finger, palm, back of the hand and wrist. During the test, the warm prosthesis was placed in a small box, with the wrists exposed, and the heat transfer coefficient and local heat transfer coefficient of the gloves were used to indicate the thermal insulation performance of the gloves. The heat transfer coefficient of the palm and back of the hand is low, the index finger, middle finger and ring finger are second, and the thumb and pinky are the highest. The warm body prosthetic foot is composed of eight pieces: toes, soles, heels, middle feet, ankles, lower calves, middle calves and protective sections. To simulate sweating, the prosthetic foot includes five sweat glands: located on the toes, soles, ankles, insteps, and side steps. Wear cotton socks on the prosthetic foot to allow water to distribute throughout the foot. The evaluation indexes are thermal resistance, moisture resistance and moisture permeability index. If connected to a pneumatic piston, it can also imitate human walking.
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