摘要:穿戴運(yùn)動(dòng)文胸可減少乳房位移,緩解乳房疼痛并保護(hù)乳房。已有研究證明文胸的不同部件具有不同的減振機(jī)理。為了能有效控制由個(gè)體差異和實(shí)驗(yàn)動(dòng)作等因素引起的實(shí)驗(yàn)結(jié)果不穩(wěn)定性,進(jìn)一步探究運(yùn)動(dòng)文胸各部件的減振機(jī)制,文章首先自主制備了30件運(yùn)動(dòng)文胸,然后使用基于3D打印技術(shù)的運(yùn)動(dòng)假人模型替代真人實(shí)驗(yàn),并對(duì)受試者進(jìn)行了統(tǒng)一,最后通過動(dòng)作捕捉設(shè)備監(jiān)測(cè)運(yùn)動(dòng)假人穿戴不同運(yùn)動(dòng)文胸時(shí)的減振效果。采集5個(gè)不同位置處的乳房位移,評(píng)估其豎直方向的位移數(shù)據(jù)。通過系統(tǒng)地研究各部件的減振機(jī)制,為運(yùn)動(dòng)文胸的設(shè)計(jì)和材料選擇提供建議。結(jié)果表明,在生產(chǎn)商制作和消費(fèi)者選擇運(yùn)動(dòng)文胸時(shí),罩杯建議選用彈性模量較大的材料和高度較高的罩杯,肩帶建議選用彈性模量較大的材料和長(zhǎng)度較短的肩帶,底圍建議選擇滌綸材料和圍度較小的底圍。
關(guān)鍵詞:運(yùn)動(dòng)文胸;3D打印假人模型;罩杯;肩帶;底圍;減振效果
中圖分類號(hào):TS941.17
文獻(xiàn)標(biāo)志碼:A
文章編號(hào):1001-7003(2025)03-0081-08
DOI:10.3969/j.issn.1001-7003.2025.03.009
收稿日期:2024-06-22;
修回日期:2024-12-12
基金項(xiàng)目:國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(2018YFC2000900)
作者簡(jiǎn)介:吳明潔(2000),女,碩士研究生,研究方向?yàn)楣δ苄赃\(yùn)動(dòng)服裝。通信作者:孫光武,副教授,gwsun@sues.edu.cn。
乳房主要由脂肪、乳腺及結(jié)締組織構(gòu)成,由于其內(nèi)部缺乏骨骼和肌肉的支撐[1-2],因此乳房中承力最大的部位是懸韌帶[3-5]。在運(yùn)動(dòng)中,特別是胸部承受劇烈運(yùn)動(dòng)時(shí),韌帶組織拉扯繃緊,使乳房產(chǎn)生不同程度的位移,長(zhǎng)此以往易造成乳房下垂或松弛[6],甚至引發(fā)乳房疾病。穿戴運(yùn)動(dòng)文胸可減少乳房位移,緩解乳房疼痛[7-9],對(duì)乳房具有至關(guān)重要的保護(hù)作用[10-11]。
運(yùn)動(dòng)文胸主要由肩帶、罩杯和底圍三個(gè)主要部件組成,各部件均具有支撐乳房的作用[12]。肩帶能夠牽拉罩杯,間接固定乳房[13]。Haake等[14]驗(yàn)證了肩帶中的非拉伸織物可以減少乳房位移,Bowles等[15]和Letterman等[16]報(bào)道了乳房較大的女性會(huì)通過收緊文胸肩帶從而限制乳房振動(dòng)。研究人員發(fā)現(xiàn)交叉式、工字型和U型肩帶比其他款式的肩帶具有更好的減振效果[15, 17-18],因?yàn)榧鐜?duì)罩杯的拉力與乳房振動(dòng)的方向相反。罩杯直接接觸乳房,是用來包裹、支撐和保護(hù)乳房的重要部件[12, 19]。由具有高彈性模量的織物制成的罩杯[2, 20]可以加強(qiáng)乳房支撐,減少乳房位移。與半杯式文胸相比,全杯式文胸由于增加了乳房的覆蓋范圍,可更廣泛地支撐乳房,并減少乳房位移[2, 15]。底圍位于罩杯下方,與罩杯直接相連。通過改變底圍尺寸增加其與皮膚的摩擦力及對(duì)皮膚的壓力,從而實(shí)現(xiàn)乳房的減振效果。Zhou等[10]發(fā)現(xiàn)加寬底圍可以更加有力地支撐乳房,而縮短底圍可減少乳房振動(dòng)。于莉君等[21]發(fā)現(xiàn)乳房位移與運(yùn)動(dòng)速度及底圍圍度有關(guān),同一運(yùn)動(dòng)速度下圍度越小,乳房位移越小。襯墊是罩杯內(nèi)部的功能性輔料,具有提升乳房、輔助塑形和提高罩杯承托性能的作用[22]。陸明艷[23]研究發(fā)現(xiàn),具有襯墊的運(yùn)動(dòng)文胸控制乳房運(yùn)動(dòng)效果最為明顯。Liu等[24]研究發(fā)現(xiàn),較大、較厚的襯墊可有效減少垂直跳躍過程中的乳房位移。罩杯下方的鋼圈有助于提升和聚攏乳房,增強(qiáng)文胸支撐力。Lee等[2]和陳曉娜等[25]證明了鋼圈可以承托乳房結(jié)構(gòu),有效控制乳房振動(dòng)。上述研究大多根據(jù)實(shí)際情況對(duì)運(yùn)動(dòng)文胸進(jìn)行個(gè)性化設(shè)置,少有學(xué)者對(duì)運(yùn)動(dòng)文胸的部件進(jìn)行歸一化研究。
前人實(shí)驗(yàn)所使用的運(yùn)動(dòng)文胸源自市場(chǎng)采購(gòu),其結(jié)構(gòu)、尺寸和材質(zhì)均難以控制。招募的部分實(shí)驗(yàn)對(duì)象非專業(yè)運(yùn)動(dòng)人員,導(dǎo)致在跳躍、跑步等動(dòng)作上具有明顯差異。因此在本研究中,通過自研運(yùn)動(dòng)文胸,從而控制罩杯、肩帶和底圍的各項(xiàng)參數(shù),并采用基于3D打印技術(shù)的假人模型替代真人進(jìn)行運(yùn)動(dòng)實(shí)驗(yàn),從而探究文胸部件參數(shù)與減振功能間的定量關(guān)系,為運(yùn)動(dòng)文胸的設(shè)計(jì)和材料選擇提供數(shù)據(jù)支撐。
1 實(shí) 驗(yàn)
1.1 文胸面料選擇
在前期的市場(chǎng)調(diào)研中,本研究發(fā)現(xiàn)適用于運(yùn)動(dòng)文胸的材料主要為錦綸、滌綸、氨綸及相互間的混紡材料?;诖耍狙芯窟x擇了多種由面料工廠提供的不同成分比例的錦氨、滌氨混紡材料,用以制作運(yùn)動(dòng)文胸樣品。
已有研究表明,在運(yùn)動(dòng)過程中運(yùn)動(dòng)文胸變形后產(chǎn)生回彈力,使乳房受到支撐和壓迫[7]。因此運(yùn)動(dòng)文胸中材料的彈性模量可以直接影響運(yùn)動(dòng)過程中的乳房位移,本研究亦采用彈性模量作為材料力學(xué)性能篩選指標(biāo)。在制作文胸前,使用DMA850動(dòng)態(tài)熱機(jī)械分析儀(TA Instruments,美國(guó))測(cè)試了多種不同材料的彈性模量。該儀器的主要指標(biāo)為:模量范圍
103~3×1012 Pa,模量準(zhǔn)確性±1%,有效施力范圍 0.001~18 N,形變分辨率1 nm。用于制作文胸的材料彈性模量測(cè)試結(jié)果和其他基本參數(shù)如表1所示。
1.2 文胸制作
運(yùn)動(dòng)文胸主要由肩帶、罩杯和底圍三個(gè)主要部件組成。為了深入研究文胸的部件設(shè)計(jì)對(duì)其減振功能的影響,根據(jù)統(tǒng)一的工藝流程制作出部件參數(shù)不同的30件承托式運(yùn)動(dòng)文胸,參數(shù)如表2所示。
單件文胸的制作過程如圖1所示。為確保實(shí)驗(yàn)不受設(shè)備差異因素影響,30件文胸使用同一臺(tái)DDL-900A-S縫紉機(jī)(Juki,日本)縫制而成。制作文胸的工藝參數(shù)符合FZ/T 74002—2014《運(yùn)動(dòng)文胸》的縫制要求。
1.3 設(shè) 備
使用實(shí)驗(yàn)團(tuán)隊(duì)自主研發(fā)的運(yùn)動(dòng)假人模型[26]。運(yùn)動(dòng)假人由兩部分組合而成,上半部分為能夠模擬乳房位移的仿真假人,如圖2(a)所示。上半部分為利用3D打印技術(shù)制作而成的包含乳房和軀干的軟體模型,其中乳房部分原材料為硅膠。乳房尺寸符合女性75 C的號(hào)型標(biāo)準(zhǔn),胸圍差為15 cm。下半部分為使用伺服電機(jī)加減速機(jī)作為動(dòng)力系統(tǒng)的機(jī)器,如圖2(b)所示。它可以模擬在不同運(yùn)動(dòng)強(qiáng)度下人體乳房的運(yùn)動(dòng)軌跡,最終可達(dá)到頻率為1/0.35 Hz,振幅為±45.68 mm的豎直振動(dòng),從而模擬人體在進(jìn)行10 km/h跑步狀態(tài)下的軀體運(yùn)動(dòng)。
實(shí)驗(yàn)采用CM Tracker動(dòng)作捕捉設(shè)備,MC 1300動(dòng)捕相機(jī)(上海青曈視覺科技有限公司)采集位置傳感器邊長(zhǎng)3 mm、發(fā)光點(diǎn)直徑0.4 mm、外圈封裝直徑10 mm的三維坐標(biāo)。采樣頻率設(shè)置為210 Hz。攝像頭的位置追蹤精度0.1 mm,角度精度0.1 °,重復(fù)誤差小于0.02 mm。測(cè)量范圍為水平FOV 90°,垂直FOV 70°。
1.4 位移測(cè)試
本研究選取左乳房為研究對(duì)象。前人的研究中大多數(shù)僅僅在乳頭處進(jìn)行研究[14, 21, 27-28],但由于乳房組織是柔軟且具有黏彈性的,乳房的運(yùn)動(dòng)是非線性的,乳頭運(yùn)動(dòng)可能不足以描述整個(gè)乳房的運(yùn)動(dòng)[7]。為了獲得整個(gè)乳房的運(yùn)動(dòng)規(guī)律,選擇了6個(gè)標(biāo)記點(diǎn)(SNP-Suprasternal Notch Point; NP-Nipple Point; UP-Upper Point; IP-Inner Point; OP-Outer Point; LP-Lower Point),如圖3所示。胸骨上切跡代表軀干的運(yùn)動(dòng),其余5個(gè)標(biāo)記點(diǎn)用于捕捉乳房的整體運(yùn)動(dòng)規(guī)律。
對(duì)CM Tracker動(dòng)作捕捉設(shè)備進(jìn)行靜態(tài)和動(dòng)態(tài)校準(zhǔn)。光學(xué)跟蹤系統(tǒng)安裝在高度為3 m的房間中,以記錄210 Hz的采樣頻率下位置傳感器的運(yùn)動(dòng)軌跡。
實(shí)驗(yàn)包括在不同乳房支撐條件下的運(yùn)動(dòng)和在裸胸狀態(tài)下的運(yùn)動(dòng),每種狀態(tài)持續(xù)8 s。將五個(gè)位置傳感器放置在乳房上,乳頭(NP)位于中心,其他位置傳感器放置在乳頭周圍4 cm處[18]。另一個(gè)位置傳感器放置在胸骨上切跡(SNP)處。傳感器用醫(yī)用膠帶粘貼在乳房和文胸上。軀干的運(yùn)動(dòng)由SNP表示,而乳房不同位置的運(yùn)動(dòng)由其他五個(gè)位置傳感器表示。五個(gè)傳感器處的平均位移被定義為整個(gè)乳房的位移。乳房相對(duì)于軀干的豎直位移通過計(jì)算得出。
1.5 實(shí)驗(yàn)數(shù)據(jù)處理與分析
1.5.1 乳房豎直位移的計(jì)算方法
在位移測(cè)試中收集的原始乳房數(shù)據(jù)是乳房的絕對(duì)坐標(biāo),包括軀干的位移和乳房相對(duì)于軀干的位移。為了去除軀干的影響,以獲得乳房的相對(duì)豎直位移,總?cè)榉肯鄬?duì)位移的計(jì)算方法如下。
Cr=Ca-Csnp
(1)
式中:Cr為乳房上5個(gè)標(biāo)記點(diǎn)的相對(duì)坐標(biāo);Ca為乳房上5個(gè)標(biāo)記點(diǎn)的絕對(duì)坐標(biāo);Csnp為胸骨上切跡切點(diǎn)的絕對(duì)坐標(biāo)。
絕對(duì)坐標(biāo)由三維運(yùn)動(dòng)捕捉設(shè)備輸出得出。
Cr,i=Cmax,i-Cmin,i
(2)
式中:Cr,i為第i個(gè)周期內(nèi)乳房相對(duì)于軀干的豎直位移;Cmax,i代表第i個(gè)步態(tài)周期中的最大相對(duì)坐標(biāo);Cmin,i代表第i個(gè)步態(tài)周期中的最小相對(duì)坐標(biāo)。
Dtb=1n∑ni=1Cr,i
(3)
式中:Dtb為總?cè)榉肯鄬?duì)位移,mm;n代表所有的步態(tài)周期。
1.5.2 乳房豎直位移減少率的計(jì)算方法
為了更精確地分析各部件的減振作用,計(jì)算減少乳房位移的百分比RBD。
RBD/%=Dtb,b-Dtb,sbDtb,b×100
(4)
式中:Dtb,b代表裸胸狀態(tài)下的乳房豎直位移;Dtb,sb代表相同活動(dòng)期間相同位置處的受文胸控制的乳房豎直位移。
RBD越大,說明文胸對(duì)乳房位移的控制效果越好,文胸防振效果越好。
對(duì)每個(gè)測(cè)量點(diǎn)(UP、IP、NP、OP和LP)的RBD取平均值,得到乳房豎直位移的總減少百分比(TRBD)。
1.5.3 乳房豎直位移顯著性分析
使用SPSS軟件分析在不同支撐狀態(tài)下乳房的豎直位移。根據(jù)不同的乳房支撐條件將數(shù)據(jù)分為六組,進(jìn)行Shapiro-Wilk正態(tài)分布檢驗(yàn)。所有位移均呈正態(tài)分布(pgt;0.05)的情況下,進(jìn)行單因素方差分析,以確認(rèn)當(dāng)運(yùn)動(dòng)假人穿著不同參數(shù)的運(yùn)動(dòng)文胸時(shí),乳房的位移差異是否顯著。
2 結(jié)果與分析
2.1 不同乳房支撐狀態(tài)下的乳房豎直位移差異
單因素方差分析檢驗(yàn)結(jié)果如表3所示。結(jié)果表明,更換不同的罩杯材料和高度、不同肩帶材料和長(zhǎng)度、不同底圍材料和圍度的乳房豎直位移均存在顯著性差異(p<0.05)。
2.2 不同乳房支撐狀態(tài)下的乳房豎直位移
圖4(a)為假人運(yùn)動(dòng)期間CM1~CM5的乳房豎直位移。結(jié)果表明,罩杯材料的彈性模量持續(xù)增大時(shí),乳房豎直位移呈減小趨勢(shì),位移均值由28.57 mm減少至17.09 mm。這主要是因?yàn)樵谙嗤那拾霃较?,?dāng)材料彈性模量增大時(shí),材料的剛度增大,罩杯對(duì)于乳房的擠壓作用增強(qiáng),材料與皮膚接觸的區(qū)域會(huì)產(chǎn)生更大壓力,進(jìn)而增加乳房和材料整體的剛度,將乳房的動(dòng)能轉(zhuǎn)化為材料的彈性勢(shì)能[7],使得乳房位移減小。Lu等[7]也做了類似實(shí)驗(yàn),發(fā)現(xiàn)拉伸材料產(chǎn)生的張力可以為乳房提供支撐,在跳躍過程中文胸吸收部分乳房動(dòng)能,并轉(zhuǎn)化為材料的彈性勢(shì)能,從而減少乳房位移。并提出在運(yùn)動(dòng)文胸設(shè)計(jì)中,需要同時(shí)考慮材料的雙向拉伸和壓縮性能。
圖4(b)為假人運(yùn)動(dòng)期間CH1~CH5的乳房豎直位移。結(jié)果表明,乳房豎直位移隨著罩杯高度的增加而減小,位移均值由36.25 mm減小至20.47 mm。這主要是因?yàn)檩^高的罩杯為乳房提供了更大的覆蓋范圍。全罩杯文胸能夠更好地限制
胸部運(yùn)動(dòng)[2, 15],使其難以產(chǎn)生劇烈的振動(dòng),減小乳房振動(dòng)會(huì)產(chǎn)生較小的乳房位移。與罩杯較低的文胸相比,罩杯較高的文胸可以提供更好的胸部支撐。
圖5(a)為假人運(yùn)動(dòng)期間SM1~SM5的乳房豎直位移。結(jié)果表明,肩帶材料的彈性模量持續(xù)增大時(shí),乳房豎直位移基本呈減小趨勢(shì),位移均值由23.8 mm減小至21.6 mm。這是因?yàn)樵谶\(yùn)動(dòng)過程中乳房的振動(dòng)導(dǎo)致肩帶受到牽拉作用,由于肩帶的牽拉,罩杯受到與胸部運(yùn)動(dòng)方向相反的張力[17]。肩帶材料的彈性模量越大,剛度越大,在拉伸的過程中越難以發(fā)生形變。因此彈性模量較大的材料用作肩帶時(shí),對(duì)于乳房的提拉作用較大,控制乳房位移的效果較好。
圖5(b)為假人運(yùn)動(dòng)期間SL1~SL5的乳房豎直位移。隨著肩帶長(zhǎng)度的減少,乳房豎直位移也一直減少,位移均值由39.84 mm減小至18.2 mm,無(wú)肩帶文胸對(duì)于乳房位移的控制效果最差。肩帶的主要作用是提供支撐力以平衡乳房的重力。當(dāng)肩帶較短時(shí),拉力的方向更接近于垂直,能夠有效抵消因重力導(dǎo)致的乳房下垂趨勢(shì)。而較長(zhǎng)的肩帶可能使得拉力的角度變得較為水平,從而減弱了對(duì)抗重力的效果,導(dǎo)致乳房豎直位移增加。并且,較短的肩帶可以更好地將乳房的負(fù)擔(dān)均勻地分布在肩部和背部,通過減少局部壓力提高整體穩(wěn)定性。
相反,較長(zhǎng)的肩帶可能導(dǎo)致壓力集中和不均勻分布,降低穩(wěn)定性,使乳房在運(yùn)動(dòng)中更容易產(chǎn)生位移。
圖6(a)為假人運(yùn)動(dòng)期間BM1~BM5的乳房豎直位移。結(jié)果表明,不同底圍材料對(duì)于乳房豎直位移的控制能力不同:滌綸>尼龍>氨綸>TPU>無(wú)底圍。位移均值從24.3 mm降低至22.31 mm。滌綸具有良好的保形性和彈性恢復(fù)能力,有助于在運(yùn)動(dòng)中保持乳房的穩(wěn)定性。沒有底圍的文胸對(duì)乳房位移的控制效果最差。
圖6(b)為假人運(yùn)動(dòng)期間BC1~BC5的乳房豎直位移。結(jié)果表明,乳房豎直位移隨著底圍圍度的減小而減小,位移均值由27.66 mm減小至22.42 mm。如果底圍較松,文胸與皮膚之間的接觸摩擦力減小,導(dǎo)致穩(wěn)定性降低,乳房運(yùn)動(dòng)時(shí)產(chǎn)生的位移就會(huì)增加。較緊的底圍可以減少運(yùn)動(dòng)過程中文胸的滑移,從而減少乳房位移。Zhou等[10]也做了類似的實(shí)驗(yàn),亦發(fā)現(xiàn)收緊底圍可以一定程度上減少乳房的振動(dòng),從而減少乳房位移。
在裸胸狀態(tài)下運(yùn)動(dòng)時(shí),假人的乳房豎直位移為54.26 mm,而穿著運(yùn)動(dòng)文胸時(shí)的乳房豎直位移范圍為17.09~39.84 mm。與裸胸相比,具有不同規(guī)格的文胸部件在運(yùn)動(dòng)期間傾向于產(chǎn)
生不同的乳房豎直位移,且裸胸時(shí)的乳房豎直位移明顯大于穿著文胸時(shí)的乳房豎直位移。
2.3 不同乳房支撐狀態(tài)下的乳房豎直位移減少百分比
除了使用乳房豎直位移外,還使用綜合指標(biāo)乳房豎直位移減少百分比來準(zhǔn)確評(píng)估運(yùn)動(dòng)文胸的減振效果。不同乳房支撐狀態(tài)下的乳房豎直位移減少百分比(TRBD)如表4所示。CM1~CM5的結(jié)果表明,罩杯材料的彈性模量與TRBD呈正相關(guān),即材料的彈性模量值越大,乳房豎直位移減少百分比越大,減少乳房位移的效果越好。CH1~CH5的結(jié)果表明,罩杯高度與TRBD呈正相關(guān),全罩杯文胸的TRBD為61.98%,無(wú)罩杯文胸的TRBD為33.01%,罩杯高度越高,減少乳房位移的效果越好。SM1~SM5的結(jié)果表明,肩帶材料的彈性模量增大,乳房豎直位移減少百分比呈增大趨勢(shì)。SL1~SL5的結(jié)果表明,肩帶長(zhǎng)度與TRBD呈負(fù)相關(guān),即肩帶長(zhǎng)度越長(zhǎng),減少乳房位移的效果越差,其中無(wú)肩帶文胸對(duì)于乳房位移的控制最差。底圍材料(BM1~BM5)對(duì)于乳房豎直位移減少百分比的影響排序?yàn)椋簻炀](58.56%)>尼龍(56.78%)>氨綸(56.66%)>TPU(55.08%)>無(wú)底圍(54.94%)。底圍圍度(BC1~BC5)與TRBD呈負(fù)相關(guān),即乳房豎直位移減少百分比隨著底圍圍度的減小而增大。
3 結(jié) 論
在本研究中,使用運(yùn)動(dòng)假人評(píng)估運(yùn)動(dòng)文胸的減振效果,可明顯降低由個(gè)體差異和運(yùn)動(dòng)姿態(tài)等外部因素引發(fā)的實(shí)驗(yàn)結(jié)果不穩(wěn)定性。通過系統(tǒng)測(cè)量和比較不同規(guī)格的文胸部件對(duì)乳房豎直方向運(yùn)動(dòng)的影響,并確定了最理想的部件,以優(yōu)化文胸支撐。與裸胸相比,具有不同規(guī)格的文胸部件在運(yùn)動(dòng)期間傾向于產(chǎn)生不同的乳房豎直位移。
1)罩杯部件。彈性模量較大的罩杯材料可以增大面料和乳房整體的剛度,將乳房的動(dòng)能轉(zhuǎn)化為材料的彈性勢(shì)能,位移減少率可達(dá)到68.07%。高度較高的罩杯可以覆蓋更大的乳房面積,通過減少劇烈的乳房振動(dòng)來減少乳房位移,位移減少率可達(dá)到61.98%。
2)肩帶部件。彈性模量較大的材料使肩帶剛度增大,對(duì)乳房的牽拉作用增強(qiáng),位移減少率可達(dá)到59.95%。較短長(zhǎng)度的肩帶可以使拉力方向接近于垂直,有助于提起罩杯,位移減少率可達(dá)到66.13%。
3)底圍部件。滌綸材料的底圍具有很好的保形性和彈性恢復(fù)能力,這有助于在運(yùn)動(dòng)中保持乳房的穩(wěn)定性,減少乳房的晃動(dòng),可以有效減少運(yùn)動(dòng)時(shí)的乳房位移,位移減少率可達(dá)到58.56%。較小圍度的底圍可以增大身體與底圍的接觸摩擦力,更好地固定文胸,減少文胸滑移,位移減少率可達(dá)到58.31%。
綜上,在設(shè)計(jì)和選擇運(yùn)動(dòng)文胸時(shí),罩杯建議選用彈性模量較大的材料和高度較高的罩杯,肩帶建議選用彈性模量較大的材料和長(zhǎng)度較短的肩帶,底圍建議選擇滌綸材料和圍度較小的底圍。
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Research on vibration reduction effect of sports bras based on three-dimensional printing manikin
WU Mingjie, SUN Guangwu, CHEN Xiaona, ZENG Lian, DONG Haiyu
(School of Textiles and Fashion, Shanghai University of Engineering Science, Shanghai 201620, China)
Abstract:The breasts are mainly composed of fat, mammary glands, and connective tissues. Due to the lack of support from bones and muscles inside, the suspensory ligaments are the most load-bearing parts of the breast. During exercise, ligament tissues are stretched and tightened. Over time, this can lead to breast droop or relaxation and may even result in breast diseases such as breast cancer. Wearing sports bras can reduce breast displacement, alleviate breast pain, and protect the breasts. Sports bras are mainly composed of three components: shoulder straps, cups, and underbands. Previous studies have shown that different components of bras exhibit varying vibration reduction mechanisms. However, the sports bras used in previous experiments were sourced from the market, making their structure, size, and material difficult to control. The recruited experimental subjects were non-professional athletes who exhibited significant individual differences in movements such as jumping and running.
To effectively control the instability of experimental results caused by individual differences and variations in movements, and further explore the vibration reduction mechanism of various components of sports bras, this study first independently prepared 30 sports bras to control various parameters of the cups, shoulder straps, and underbands. Then, a manikin based on three-dimensional printing technology was used instead of human subjects to standardize the experiments. This approach aimed to reduce experimental errors caused by individual differences. Motion capture devices were used to monitor the vibration reduction effect of different sports bras worn by the manikin. The vertical displacement data were evaluated by collecting breast displacement data at five different positions. Finally, a significant analysis was conducted on the vertical displacement of breasts under different breast support conditions. The breast displacement reduction rate was used as an indicator to evaluate the vibration reduction effect of different component parameters of the bra. This article employed self-developed sports bras to control various parameters of different components. The bra components were personalized. A new method for evaluating breast displacement was provided by using a three-dimensional printed motion manikin instead of human subjects. The experimental results indicate that using a sports manikin to evaluate the vibration reduction effect of sports bras can significantly reduce the instability of experimental results caused by external factors such as individual differences and movement posture. Compared to bare breasts, bra components with different specifications tend to produce varying vertical breast displacements during exercise. The cup material with a higher elastic modulus achieved a displacement reduction rate of 68.07%; a higher cup height reduced displacement by 61.98%; shoulder strap materials with a higher elastic modulus reduced displacement by 59.95%; a shorter shoulder strap length reduced displacement by 66.13%; the underband made of polyester material reduced displacement by 58.56%; and a lower circumference of the underband reduced displacement by 58.31%. When manufacturers create and consumers choose sports bras, it is recommended to use materials with a higher elastic modulus and a higher height for the cups, materials with a higher elastic modulus and shorter shoulder straps for the shoulder straps, and polyester materials with a lower circumference for the underbands.
The use of sports manikin to evaluate the vibration reduction effect of sports bras provides a new evaluation method. By integrating three-dimensional printing technology and principles of ergonomics, the quantitative relationship between bra components and vibration reduction function was studied, providing suggestions for the design and material selection of sports bras.
Key words:
sports bra components; three-dimensional printed manikin; cups; shoulder straps; underbands; vibration reduction effect