Functional Design And Performance Research Of Fully Molded 3D Bra Pad

As the majority of women pay more attention to the health and beauty of their breasts,bra has become a necessary item of clothing.Bra pads,as an important part of women’s bras,determine the comfort and functionality of bra products.The types of pad can be divided into general cotton chest pad,silicone chest pad,breast paste,inflatable pad,super-thick pad,etc.Bra pad materials include polyurethane foam,latex,fabric laminated fabric,non-woven fabric and spacer fabric.At present,the most widely used material is polyurethane foam,as known as sponge,which is a compound of petroleum and asphalt.It is chronically harmful to the human body.The manufacturing process is complicated,and most of the materials are cut off and discarded as waste materials,causing waste of raw materials and environmental pollution,and the waste is difficult to recycle.In addition,the polyurethane foam pad has poor air permeability during use,sultry and difficult to bear,making the wearer feel moist and sticky,and it is easy to turn yellow and black,and it is easy to breed a large number of bacteria,which is harmful to human health.Based on the above reasons,it is necessary to improve and explore the design,material and manufacturing process of bra pads to obtain a fully formed,healthy,cool and breathable bra pad.The emergence of 3D printing brings a new research direction to underwear manufacturing.As a mature technology in recent years,3D printing technology has been gradually applied in many fields of production and life.In this paper,3D printing technology is combined with bra liner manufacturing to explore the problems existing in the traditional bra manufacturing industry,aiming to develop 3D printed full shape bra pad suitable for women’s daily wear and good air permeability.By using UG and Rhino3 D software modeling to design bra pad,and exploring the process of 3D printing bra pad,through testing and analyzing product performance,a new direction of intelligent digital research and development of bra pad manufacturing industry was obtained.In the early stage,TPU95 was selected as the printing material for this project through investigation and basic research.Through the method of forward modeling,a series of bra pad models are established and the factors affecting the air permeability and plastic shape of the pad are explored.The details include:(1)Two cushion structures are designed;they are single-layer solid and double-layer hollow.On the basis of 75 B bra pad,the initial pad model P1 with a thickness of 4.2mm and a diameter of circular air vent of 6mm was designed.On the basis of the same air hole area as the initial model,the pad P2 with a hole size of5.3mm and a square air hole shape was designed.Pad P3 with a hole diameter of3.3mm and an hexagon shape;Pad P4 with 8mm circular vents;Honeycomb pad P5 with a side length of 5mm;Four different vent distribution methods are designed,horizontally distributed P8(4mm～8mm),longitudinally distributed P9(4mm-8mm),shrinkable pad P6,divergent pad P7.And designed double-layer hollow pads K1,K2,K3,K4 with the same parameters as the single-layer solid vents.(2)By testing the air permeability and washing resistance of the pad,the results show that for the single-layer solid pad model,under the condition of the same vent area,the moisture permeability of the circular hole is the largest,the moisture permeability of the hexagonal hole is the smallest,and the square hole is in the center.In the hollow model,the WVT value of K3 is 215.5357,which is the largest among the four models,and its air permeability is better than that of K1 and K4.Compared with traditional sponge pads,the dimensions of the 3D printed pads before and after washing remain unchanged,and the quality difference is about 0.05.The 3D printed pads have better washing durability.(3)Through subjective evaluation and shaping test,3D printing cushion has good support and shaping effect,and it is not easy to deform compared with sponge cushion and rubber cushion.(4)The pad permeability process was numerically simulated by ANYSYS FLUENT.The results show that the wall effect at the edge of the vent will reduce the fluid velocity and the performance of the square hole is better than that of the hexagon hole.The turbulence at the wake of longitudinal-distributed vents is small,which is not conducive to the air permeability of underwear under the heat conduction efficiency.It is found that the design of longitudinal-distributed circular holes is not ideal.It provides some reference for the design and improvement of 3D printing pad structure.The comprehensive analysis shows that the pad with a diameter of 4 mm to 8mm is the best.It provides some reference for the design and improvement of 3D printing pad structure.