| Backpack is one of the necessary equipments in outdoor sports. It is required not only has some general characteristics such as light, beauty, but also its safety and comfort are getting more and more people’s attention, especially these characteristics including breathable, moisture, perspiration, laminating, pressure distribution and gravity transfer during exercise. Backplane is the cadre in carrying system of backpack, it plays an important role in the pressure dispersion. Its main function is reasonably assign weight to all parts of the body, in order to avoid the weight focus on the shoulders or one muscle causing muscle fatigue and even damage. In addition, it provides the center of gravity adjustment to increase balance and safety during exercise.According to the principle of carrying load, flank above the coccyx is the main anchorage, and flank connected to the top of bilateral hip bone is the main area of the force, the shoulders are the areas of assisting to stand the force and mastering balance. The lower back position (L3-L4) bears the most of the weight of the body. So the lumbar spine especially lower back position is the most prone parts to put a strain which should be paid enough attention to the whole backplane in whole designing process.The backpack applys load to body from the exterior which will change the center of body gravity and affect the body’s stability when people carry something. The uneven load will lead to lower back pain, idiopathic scoliosis, excessive kyphosis, lordosis and other musculoskeletal diseases. Thus, while reducing the burden of carrying, it is beneficial to reduce the partial pressure of back from backpack by designing and improving the backplane system of the backpack, to some extent, it can reduce the risk of illness.The study is based on various morphological characteristics of the lower back in motion state and the pressure test data analysis. Aiming to find the key factors which influnce the pressure distribution and carrying comfort, thus designing a backplane structure which will better disperse waist and back pressure. Carries on the simulation load bearing esperiment to optimize and design production back surface shape, then makes the finished product knapsack in the end. We use sEMG, Pliance-X pressure tester and other means to execute simulation load test, optimize and produce the backplane structure with pressure dispersion effect, thus creating the finished package for validation. By summarizing optimized parameters, we can provide experimental evidence for the latter part of the backplane data structure design. We aim to maintain the normal physiological curvature of the spine, making the supporting of shoulder and lumbar spine ergonomic, keeping proper air flow in the backplane structure design to ensure its comfort.This study consists of four parts. The first part is to measure lowerback curve of human and analyse the pressure distribution ratio. Selecting suitable subject:choose standard size whose BMI are similar, measure parameters characteristic (neck point, waist and hip bumps points, etc.) of curve of waist and back curve in different motion states (stand still,12° climbing simulation state) and the percentage of every parts of the waist and back pressure distribution. The second part is based on the principles of load-bearing to design the backplane’s structure.Test for the pressure distribution of current ordinary backpack by Pliance-X pressure tester, sEMG and other equipments. And by analysing of experimental datas combined with ergonomics to determine the main points of lower back which impacts the pressure dispersion The third part is building 3D model and producing the finished package. Using Rhino software to accomplish three-dimensional modeling for backplane architecture designed. Testing the physical and mechanical properties of several kinds of back bonding materials commonly used in the market in order to select the suitable backplane materials to produce a finished backpack. The fourth part is to retest for backplane. Testing the finished package by Pliance-X and sEMG tester, to simulate outdoor sports equipment. In the whole test, mainly test the shoulders, lower back of the major muscle (left and right trapezius, left and right erector spinae) under certain loading, and analyse the changes in their sEMG and pressure-sensitive.Research indicates:(1) When carrying a backpack to make a 12 degree simulation climbing movement and the level of uniform motion, the main force point is erector spinae and trapezius. But muscle activity of erector spinae showed more severe compared to the trapezius.(2) By EMG feature analysing to collected sEMG signals, it can be concluded that the original data 12 degree climbing state data are higher than 0 degree uniform when walking. Compared the improved backplane with common backplane in the same movement states, the datas on MA,MPF, INT, RMS were significantly higher than common backplane. It indicated that changing the angle of the torso can cause changes in muscle electrical signals during weight-bearing walking. At the same time, it will also affect the point of muscle fatigue and impact the muscle power, and the number of discharges per unit time, which will cause muscle fatigue earlier.(3) Reasonable gravity delivery and effective support played a significant role in the lower back pressure dispersion. The pressure test analysis showed that the shoulder, back, waist weight ratio was 6:1:3 for ordinary backpack, improved ratio was 3:3:4. Combined with "visual analogue Analysis"(ie "VAS"), we can found that the improved backplane’s comfort has improved significantly in the process of carrying lower back.(4) Temperature and humidity contrast experimental study showed that reasonable back support can improve the comfort. Under the condition of constant load and experimental conditions, the normal back plate’s temperature and humidity are suddenly rising in the end of the experiment Omin.In the whole 15min’s experimental test, the improved back plate’s temperature and humidity test curve are smaller compared with the normal back plate. Combined with the "VAS" test method, the improved back plate can improve the air permeability of the backpack, thus improving the comfort of the backpack.(5) According to ergonomics, waist and back curves, and Rhino three-dimensional modeling design, sEMG and Pliance-X pressure test, we can see the model of the back of the building, so that the back of the body can better fit in with the back of the body shape, thus make the bear become more comfortable. |
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