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There is no united definition of the large breast size in the entire brassiere industry as well as in medicine. Many misconceptions appear that whoever looks fat likewise have large breasts. And some may define it as E cup or above due to the difficulties in purchasing bra in the recent market or grading the contour cup shape. Indeed, plus size usually refer to large chest women who may not really look fat.
2.1.1 Medical standard
In medicine, there are many different standards on large breast size. KL.Dundas from The Royal Australian and New Zealand of Radiologists (2007) defined that large breast size can be divided into two categories: the bra size and the cup size. The bra size is the component size of chest-wall and the cup size is referred to the mammary gland components. Women who have cup size D or above or bra size 18 or above can be classified as plus size. Another study about the relationship between the respiratory and measurement method and the bra size calculation (Mcghee, D.E. & Steele, J.R., 2006) involved subjects of large breast women. They indicated those with cup size C or above as large breast women. In other research of medical scanning, Indra. J. Das (2006) also defined large breast Japan women whose distance of chest-wall were greater than 22 cm. It can be seen that there is no united standard of the large breast size among the medicine.
2.1.2 Market Standard
People nowadays tend to have bigger cup size than before. Therefore, the plus size market is growing rapidly among the popular lingerie brands recently. Wacoal Hong Kong Company limited (2008) once launched a line mainly for large breast size women named "WACOAL Queen Size". Cup size from C to I, which means having 15 cm up to 30 cm difference between upper bust girth and lower bust girth, and band size up to 120 cm or 52 inch are available.
For the reason of simplicity, cup size of C or above with shoulder pain problem would be categorized as large breast women in this study even though it is not really the market standard and the common practice in the lingerie industry.
2.2 Problems faced by large breast women
Many women envy those who have large breasts since they think it is a symbol of sexy appeal. Many even undergo breast augmentation to enhance their bodies with silicone and saline implants (2010). However, it may not be the same feeling for the women who carry the heavy breasts around. The large breasts may trigger multiple problems like physical problems and psychological problems (Dave, 2009). These may affect our daily life or even our social life.
2.2.1 Physical problems
Plenty of health websites and journals claimed that the weak chest tissue could easily be over stretched by the excessive weight of the large breasts and as a result causing a lot of problems like upper and lower back pain as well as shoulder pain. Sheer gravity was the main reason causing shoulder pain problem. The heavy breasts makes the shoulders have to work extra hard to keep the back spine straight from being pulled down by them (Ardian, 2010). The arching action also add lots of load to the acromion (Figure 2.1), which is the highest point of shoulder and one of the most sensitive parts of the body (Carol, 2002). Pain feeling would rise and the dark red marks would be left on the shoulder because of the excessive load from the breast and the tighten bra straps after period of time (Toni, 2008). Besides, there are many blood vessels and nerves like Brachial plexus located underneath the skin which are extremely sensitive to pressure and pain feeling. They are the nerve fibres that serve sensation and motor function in the shoulders, arms, and hands travel to and from the spinal cord in the neck (Carol, 2002). So, the wearer had fatigue and pain feeling easily when there is an excessive load applied on the shoulder. Sometimes, the wearers may even have upper arm pain additionally. Due to the shoulder pain as well as the arm pain feeling, exercise is not an easy task for busty women. Because their breasts would be all bouncy when they move and this may cause pain as the muscles around the breasts area are being consistently pulled during the sport activity (Carla Ardian, 2010).
Figure 2.1 The acromion
Source: Carol A. Oatis. (2002), Kinesiology the mechanics & pathomechanics of human movement, pp. 123
2.2.2 Psychological problems
Apart from the physically pain, large breast also accrue to women with emotional problems. Many women dislike their large breasts because they make them look fatter. It is harder for them to find some pretty clothes. Even worse, the patterns on the top would become deformed and as a result make them feel frustrated. These would prevent them from enjoying a higher quality of life (Dave, 2009). Therefore, this is not surprised that their self image drops dramatically because of all these factors. To improve the situation, some may even take the breast reduction surgery. According to the American Society of plastic Surgeon's 2007 nation plastic surgery statistics, over 100000 women had taken the breast reduction surgery in 2007. And there were 25% growth when compared with the same survey last year (Toni, 2008).
Base on the above physical and mental problems, the objective of this study is to look into the possibility of distribute or minimize the pain feeling caused by excessive pressure load from the shoulder straps.
2.3 Current plus size bra market practice
Many plus size bras are available in the existing market. They are specially designed in terms of comfort and support for women with large breasts. Besides, some accessories could be found as auxiliaries for minimizing the pressure and pain feeling.
Figure 2.2 An example of plus size bra
2.3.1 Special design of bra cup
Plus size bra always appears as full cup with higher neckline to cover the entire breast. The full cup is designed to give more support for the breasts to help keep the shape and fullness of the breast. Most of them are thin padded cup with wire and inner sling for minimizing the movement of the breasts. Full cup bras are ideal for larger breast sizes and pregnant women as less support can lead to a slight sagging of the breasts and back pains (My Fine Lingerie, 2010).
Figure 2.3 An example of full cup bra with higher neckline
2.3.2 Special design of wings
Wider wings with side bones are another features of plus size bra. They are used to keep the bra firmly in place and help to limit the breast movement. Hooks and eyes are available at the end of the wings for adjustments. Appropriate tension can be applied to the wearer so as to fit well with a secure frame for breast support.
Figure 2.4 Wider wing with hooks and eyes
2.3.3 Special design of shoulder straps
The average breast weight of adult women was around 200g without any pregnancy and lactation. The pregnancy women could have breasts weight from 400g to 600g and up to 800g in lactation. D cup size or above plus size women could have the breasts weight same as the pregnancy and lactation women (Laurence D.J, 1991). Therefore, the straps of plus size bra should be wide enough to allow better distribution of force. Mostly, the widths of them are more than 10mm. Some straps for plus size bra may even reach 19mm or more. It should contain minimal elasticity and good recovery at the same time as well. Sometimes, the front part of the straps appears as rigid to limit the breast movement. Also, the tension of shoulder straps should fit different body lengths by using strap material with proper power and elasticity or applying adjusters. If there are not enough adjustments of the shoulder straps, the required lift-up function cannot be provided if it is too loose, or cause fatigue and pain if it is too tight (Zhou Jie, 2010). Besides, padded or cushion straps are other designs for easing the neck and shoulder pain.
Figure 2.5 Wider and padded shoulder strap
One of the examples of accessories for minimizing the shoulder pain and discomfort is the shoulder pad. It is common in the U.S., U.K. or Europe, but it is not easy to find in Asian countries, especially in Hong Kong since lingerie brands mainly target on the small size. There are various kinds of shoulder strap pads with some designed in small size in foam material or gel pad to provide shock absorb effect and some designed in a hand- size big. The big pad is specially designed for post surgery women like mastectomy, chemotherapy and pacemaker implantation.
The product shown in figure 2.5 and 2.6 were the attachable shoulder strap foam pad and silicone pad respectively which could provid the free movement along the shoulder straps. They could be the extra supporter placing under the straps for easing shoulder pain. However, the thickness of the shoulder pad could easily show though the outerwear, an innovation from the online shop called covered shoulder pad shown in figure 2.7 can help this. It is a pad with a channel in between for placing shoulder straps as well as providing a smooth shoulder contour with its finely tapered edges.
Figure 2.6 An example of shoulder strap foam pad
Figure 2.7 A shoulder silicone pad
http://images.herroom.com/items/braza-brz001-2100-gs.jpgFlip Flap Satin Covered Shoulder Pads
Figure 2.8 Covered shoulder pad
2.4 The mechanism of shock absorb
According to a research done by Zhou Jie (2010), when the human body collides with the ground, impact forces develop. With each foot strike during walking or running, the shock wave would transmitted throughout the body and ultimately reach the head. The shock attenuation is brought by the shock absorbers in the human body such as joint positioning, muscle activity, synovial fluid, bone, and articular cartilage. Any forces that are not absorbed by the lower extremity will be transmitted up to the kinetic chain, which gives a force to breast and makes breast move.
The movement of breasts results in pressure to the body. The applied load was 1.25 times of the body weight while walking. Shoulder pad provides a cushion effect to the wearer and it acts as a protector to reduce the pressure transmitted to the shoulder. Once there are compression force stroke on the cushion, the cushion was compressed and stored part of the strain energy. The cushion would become stiffness and thinner (Kevin, 1999).
The strain energy stored inside the cushion would then be converted into heat energy and dissipated by the air. When the compression load removed, the cushion would be recovered into its original shape called energy return (Pi, et al., 2008). Because of the dissipation of part of the impact energy, the wearer would then feel lesser resilient force from the ground and superior comfort of relieving the shoulder pain.
2.5 Definition and functions of elastics
Elastic is an essential component of lingerie. It is a narrow fabric which does not exceed 18" in width and it can be classified as woven or knitted. Elastics have been widely used in textiles as well as lingerie like the upper and lower band of wings, shoulder straps and the opening of the briefs. This is all because it can position the garment, support the garment as well as create a finished edge or hem (Yip, 2010).
2.6 Shoulder straps
Shoulder strap is the essential part of the whole bra (Click n Click, 2010). It is one of the narrow elastics which functions to support and control the movement of the breasts. The breast weight could act as a large load on the straps and in turn, excessive pressure on the shoulder of the wearers (Zhou Jie, 2010). Therefore, to provide more comfort to the wearer, shinny surface with matt back are always the appearance of the shoulder straps (Yip, 2010).
2.6.1 Constructions of shoulder straps
There are two basic constructions for shoulder strap which are woven and crochet (knitted) elastics. For woven straps, it is the narrow woven fabric having stretch properties consisting of monofilament nylon yarns woven together (Thompson and Bick Harlequin, 1952). They have smoother, finer and flatter surface as well as being more supportive than knitted elastics. For knitted straps, they are always produced by interloping which means forming yarns into loops and intermeshing the loops into a structure (LAMB Knitting Machine Corporation, 2010). And most of them are warp knitted. Knitted straps have higher elongation compared to the woven straps. Small gaps would appear when stretched. Also, it is much cheaper in price (Yip, 2010).
There are several areas that must be taken into considerations during the fabric construction:
1. Details of materials
Types of filaments, number of counts and ends used in both warp and weft direction are recorded in a basic unit of fabric construction.
2. Details of fabric construction
The arrangement of picks and ends are clearly recorded in a data sheet, specifying which types of nylon filaments and spandex used.
3. Production requirements
Details of number of reed, picks per unit length, elongation and shrinkage requirements are also needed to be laid down for reference.
2.6.2 Product types
There are two types of bra straps in turns of woven and knitted. Woven bra straps are available in 8 - 27mm. Plus size bra tends to use wider shoulder straps to help the distribution of force. It is more shinny and smoother on the surface to provide a better appearance and matt with brushes at the back to provide a comfort feeling to the wearer. There are a variety of surface pattern like stripes, zig zags, checks, plain satin effects and Jacquard. Different types of edge can be found in the market, for examples, plain, picots, loops, frills, double loops, etc. For knitted bra straps, matt and shinny appearance are available in the market. Surface patterns like loops and curves can be found on them. Picots, loops and double loops are the common edge of the knitted straps. Although the support is not as good as the woven bra straps, it is relatively cheaper and has more different kind of fashion styles (Yip, 2010).
Figure 2.9 Woven shoulder straps
Figure 2.10 Knitted shoulder straps
2.6.3 Materials used in shoulder straps
A variety of materials were used in the construction of shoulder straps such as nylon, polyester, spandex or Lycra and metallic yarn. 90% of shoulder straps use nylon as nylon can be dyed more easily with lower temperature compare to polyester. For spandex, it can be stretched for many times and recover to its original length after load is removed. It is due to its special arrangements of the molecular structure (Yip, 2010). The structure consists of long chain molecules that take on the conformation of large random coils. These long chain structures show soft and flexible properties at room temperature. When stretched, they will deform or uncoil and return back to its original dimension after removing the force (Woods, 1987). Spandex usually wrapped around by nylon or polyester yarn and forms elastic by weaving. Sometimes, metallic yarns are used to provide a more attractive and shinny appearance (Yip, 2010).
2.6.4 Stretch and recovery of shoulder straps
Stretch or elongation, recovery and modulus are three main considerations during construction of elastics. Both of them play the important roles in determining the supportive and comfortable level of a shoulder strap (Yip, 2010).
Elongation, combines with strength, indicates the ability of a yarn of fabric to absorb energy. (John & Sons, 1977) Elongation means the percentage extension at the specified load. When objects are put under stress, they will stretch before breaking. If the stress is not great enough to break the object, the deformation is usually temporary and the object's original shape will return when the stress is removed. Knowing how shoulder straps will elongate is critical for designing a bra for large breast women which can ensure that they do not elongate so much that they no longer have enough strength to withstand the forces while elongated (Mark Kennan, 1999). To measure this, the original length of the shoulder strap sample should be subtracted by the length of the strap which under specified load first. And then the result would be divided by the original length of the strap. Lastly, it is to multiply the result by 100%. The final result would be the elongation of the strap. Below is the equation of elongation.
Length under specified load - original length X 100%
Recovery means the percentage of the elastic that can be recovered when the load is released. After a load is released from a stress-strain test, some of the total deformation is recovered as elastic deformation (Mark Kennan, 1999). The higher the percentage states that the better the recovery a strap has. It is also very important to shoulder straps as they should keep a certain recovery rate say 85 % even after using repeatedly. To measure this, the elongated length of the straps should minus the recovered length and the original gauge length respectively. And then the former would be divided by the latter one. Lastly, the result should be multiplied by 100%. The final result would be the recovery of the shoulder strap. Below is the equation of it.
___Elongated length (in.) - Recovered length ___ X100%
Elongated length (in.) - Original gauge length
Modulus means the amount of load (in lbs) needed to extend the elastics to 20%, 40%, 60% and 80%. In another words, it is the ratio of pressure (stress) applied to a body to the resistance (strain) produced by the body. The higher the modulus, the larger the amount of load has to applied to extend the straps (Yip, 2010). This is another important consideration for the construction of strap since the modulus should not be too low as straps should have certain stiffness to support the breasts weight.
Elongation, recovery and modulus are three very vital checking points before the shipment of each batch of shoulder straps. Therefore, control of them should be extremely careful within the set tolerance. Besides, different cup size bras should match with different shoulder straps with different level of elongation, recovery and modulus because of the comfort and support level provided.
2.7 Physical properties of spandex fibre
Other synthetic fibres
Elongation at break (%)
(break tenacity, g/tex)
Thickness available (tex)
Stress at 200% elongation (g/tex)
Melting point - ËšC
Moisture regain (% at 21ËšC, 65%RH)
Table 2.1 Physical properties of spandex fibre
From the table, it can be seen that, although the nature rubber also has a high value of elongation at break, it is not suitable for making elastic fabric because of its low tensile strength and high value of thickness (Randall and Lee, 2002).
2.8 Innovative design of shoulder straps
2.9 Design frameworks
In the overall product life cycle, before the product manufacturing, product development is very important as many ideas generate and integrate to form new products. There are many different frameworks for product development and design, but not all of them provide the specific ideas for functional apparel. Only DeJonge (1984) and Watkin (1988) provide the specific ideas in this aspect (Chan, 2001).
2.9.1 DeJonge's model
DeJonge (1984) proposed a process for the development of functional occupational clothing that places importance on identifying user needs and analyzing user situations through systematic exploration. The full process guides the designer step-by-step from initial request to prototype completion and evaluation (Table 2.2). DeJonge provide a systematic model on design research and this helps designers a lot to determine the design specifications. This model provides a clear division between the development of design specification and the establishment of design criteria. It can clearly list out the important issues that designers should consider during the whole design process(Chan, 2001).
DeJonge's design stage
1. Initial request made
Define design problem
2. Design direction explored
Find design directions
3. Design goals defined
Define the goals for research
4. Research for specification developed
Develop in-depth research to find design factors
5. Design criteria established
Ranking and weighting design criteria
6. Prototype development
Develop the prototype for the design according to the criteria made in the previous stage
7. Prototype evaluation
Evaluate the prototype
Table 2.2 DeJonge's design process
2.9.2 Watkin's model
Watkins' model (1988) adapts seven-step approach of design process that includes acceptance, analysis, definition, ideation, selection, implementation and evaluation. This model focuses more on the problem solving stages with a heavier weighting on the prototype implement part.
Get motivation and find reasons to devote time and effort to the design problem
Find out all aspects of design situation by learning and interviewing
Determining the most essential elements by sifting through the mass of data and ideas collected in the previous stages
Generate ideas and creative things as many as possible
Select the best idea
Take action and try out the best idea
Analyzing what happened when action was taken
Table 2.3 Watkin's design process
2.9.3 Selection of design framework
Although both Dejonge's and Watkin's models provide the specific ideas for development of functional apparel, the later one is more or less used for the teaching of design process (Chan, 2001). Among these frameworks, DeJonge's functional design process is generally accepted by clothing and textile researchers to be a landmark for the development of the design processes. It has also been used to guide research into the development of garment design criteria and prototype. Examples of previous research that have used the full or adaptations of DeJonge's basic design framework are clothing for women with physical disabilities (Carroll, 2001), intimate apparel designs for women (Chan, 2001) and hospital clothing for neonates (Bergen et al.,1996). For the above reasons, this study was conducted to design and develop a set of new product of shoulder strap based on DeJonge's design framework. Details of the design process based on DeJonge's framework are presented in Chapter 5. Current scientific knowledge and systematic design framework are necessary to guide scientific investigation of design and development of shoulder straps.