Abstract:

To improve the ergonomic performance of firefighting personal protective equipment and enhance flexibility in rescue operations, human ergonomic tests were carried out on a controllable environmental test platform to quantify the air gap distribution under fire protective clothing during firefighters' stair ascent and descent. Test subjects completed stair ascent and descent movements, and each complete gait cycle was divided into four characteristic gait phases. Subsequently, 3D human body models of both nude and clothed states were obtained using 3D body scanning technology. Then, Geomagic software was used to denoise and optimize the scanned models. The air gap thickness and CA ratio of different body segments was calculated using the volumetric method and CA ratio formula. The results indicate that the air gap of the trunk is thicker than that of the lower limbs throughout the gait cycle. The air gap thickness of the chest, back, and abdomen ranges from 35 to 40 mm, while that of the legs and buttocks ranges from 25 to 30 mm. During stair ascent, the air gap thickness of bent legs is 2 mm thinner than that of straight legs. During stair descent, the air gap of flexed legs changes slightly due to the small amplitude of passive bending. The air gap of the buttocks fluctuates with the change of hip posture. The CA of the right leg, left leg, and buttocks shows dynamic changes closely associated with limb movement postures, with the buttocks exhibiting a higher CA values.

Key words: firefighters, stair ascent and descent, gait cycle, air gap, air gap, contact area (CA)