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BIOMOMENTUM力學(xué)試驗(yàn)機(jī)--人發(fā)機(jī)械性能評(píng)估

EVALUATION OF THE MECHANICAL PROPERTIES OF HUMAN HAIR

We were recently asked if our mechanical tester has the capability of evaluating the mechanical properties of single fiber human hair. In our lab, a scientist has been devoted to this feasibility study.

 

The hardest part of this work was to develop the proper gripping fixtures to easily mount the hair on the tester to be able to perform tensile and torsion testing. Following few attempts, it was found that the simplest and most reproducible mounting method was based on the use of a pair of off-the-shelf syringe needle tips. On the bench, the hair fiber was inserted through the two needles facing each other and spaced by a predefined gauge gap. A single drop of cyanoacrylate glue was applied in the plastic cavity of each needle to secure the hair in place. Two needle tip holders with the same tapered shape as a regular syringe were mounted on the Mach-1. These two holders were fastened facing each other at the center of a testing chamber under a 17N multiaxis load cell. The double-needle hair assembly was then firmly inserted over the holder (see Image 1).

 

After zeroing the load, and considering the relative position of the vertical stage, the initial length of the hair at full extension (when no load is applied) was measured using the Mach-1 Motion's "Find Contact" function. A sinusoidal deformation in the elastic region was applied for 30 cycles at 0.5, 1 and 2 Hz. A Dynamic Mechanical Testing analysis was conducted as per MA056-SOP04-D to extract the complex tensile storage and loss modulus components. Dynamic testing showed an increase in phase magnitude with increased frequency. This result was expected and explains an increase in plastic deformation (loss modulus) with increased frequency.

 

The tensile modulus and ultimate tensile strength were also measured and calculated (Mach-1 Analysis software) during a tensile load ramp to failure (see Image 2 - Tensile test output until failure). The results were found to be in accordance with literature (Lee, 2012): 930 MPa ultimate tensile strength, 6.5 GPa elastic modulus. Other tests were completed using a rotational stage to apply torsion to the hair until rupture occurred. For two samples, the results were 175 and 179 turns before failure. A camera feed with a 10X lens was used to visualize the torsion of the fiber in real time.

The plastic torsion of the hair remains even after breakage and can be visualized under a microscope (see Image 3 - Post-torsion photograph using 20x microscope). 

 

During torsion, the generated torque around the Z-axis was too low to be measured by the 17N multiaxial load cell. However, the vertical contraction of the hair induced by torsion created a vertical contractile force that was measured by the Fz channel of the cell. It is assumed that through proper theoretical modelling of this test configuration, this axial load could be used to indirectly measure the torsional shear strength of the hair. 

 

Different indirect ways of quantifying the torsional properties of fibres have also been proposed in literature. For example, by relating the initial gauge length to the number of rotations before rupture, a theoretical value for fracture angle can be obtained. From a basic analysis, the fracture angle was found to be between 26 and 33°.

近，我們被問(wèn)到我們的機(jī)械測(cè)試儀是否具有評(píng)估單纖維人發(fā)機(jī)械性能的能力。在我們的實(shí)驗(yàn)室中，一位科學(xué)家致力于這項(xiàng)可行性研究。

 

這項(xiàng)工作困難的部分是開(kāi)發(fā)合適的抓持裝置，以將頭發(fā)輕松安裝到測(cè)試儀上，以執(zhí)行拉伸和扭轉(zhuǎn)測(cè)試。經(jīng)過(guò)幾次嘗試，發(fā)現(xiàn)簡(jiǎn)單，可重復(fù)的安裝方法是基于使用一對(duì)現(xiàn)成的注射器針尖。在工作臺(tái)上，將毛發(fā)纖維穿過(guò)彼此面對(duì)的兩個(gè)針頭插入，并以預(yù)定的標(biāo)尺間隙隔開(kāi)。將一滴氰基丙烯酸酯膠滴到每個(gè)針的塑料腔中，以將頭發(fā)固定到位。在Mach-1上安裝了兩個(gè)具有與普通注射器相同的錐形形狀的針尖支架。將這兩個(gè)支架在17N多軸稱(chēng)重傳感器下的測(cè)試腔室中心彼此相對(duì)固定。

 

將負(fù)載歸零后，考慮垂直臺(tái)的相對(duì)位置，使用Mach-1 Motion的“查找接觸”功能測(cè)量在*伸展時(shí)（未施加負(fù)載時(shí)）頭發(fā)的初始長(zhǎng)度。在彈性區(qū)域以0.5、1和2 Hz的頻率施加正弦形變形30個(gè)循環(huán)。根據(jù)MA056-SOP04-D進(jìn)行動(dòng)態(tài)力學(xué)測(cè)試分析，以提取復(fù)雜的拉伸存儲(chǔ)和損耗模量分量。動(dòng)態(tài)測(cè)試顯示相位幅度隨頻率增加而增加。該結(jié)果是預(yù)期的，并解釋了塑性變形（損耗模量）隨頻率增加而增加。

biomomentum多軸機(jī)械測(cè)試儀Mach-1
 Mach-1多軸機(jī)械測(cè)試儀是模塊化集成壓縮，拉伸，剪切，摩擦，扭轉(zhuǎn)和3D壓痕映射、電位分布等測(cè)試設(shè)備
   biomomentum至1999年以來(lái)，專(zhuān)注用于測(cè)試生物材料，組織和關(guān)節(jié)軟骨機(jī)-電特性產(chǎn)品的設(shè)計(jì)、開(kāi)發(fā)、制造和商業(yè)化的創(chuàng)新解決方案20余年。
    其mach-1多軸向多功能組織材料機(jī)械特性測(cè)試分析系統(tǒng)已經(jīng)成為組織材料機(jī)械-電位測(cè)試分析的黃金標(biāo)準(zhǔn)。
  1、多功能、多軸向，適用樣品范圍廣：
•1.1、從骨等硬組織材料到腦組織、眼角膜等極軟的組織材料
•1.2、從粗的椎間盤(pán)的樣品到極細(xì)的單纖維絲
2、力學(xué)類(lèi)型測(cè)試分析功能齊全：
2.1、模塊化集成壓縮、張力、剪切、摩擦、扭轉(zhuǎn)、穿刺、摩擦和非平面壓痕、3D厚度、3D表面輪廓等各種力學(xué)類(lèi)型支持,微觀結(jié)構(gòu)表征及動(dòng)態(tài)力學(xué)分析研究
2.2、多物理場(chǎng)耦合加載測(cè)試
•3、通高量壓痕、壓縮測(cè)試分析（48孔板中壓痕測(cè)試分析）
•4、高精度、高分辨率:
•4.1、位移分辨率達(dá)0.1um
•4.2、力分辨率達(dá)0.025mN
•4.3、樣品直徑小25um
•5、行程范圍廣：50-250mm
•6、體積小巧、可放入培養(yǎng)箱內(nèi)
•7 、DIC （Digital Image Correlation)數(shù)字圖像相關(guān)法非接觸式的高精度位移、應(yīng)變測(cè)量
•9、活性組織電位分布測(cè)試分析
•10、產(chǎn)品成熟，文獻(xiàn)量達(dá)上千篇
biomomentum多軸機(jī)械測(cè)試儀Mach-1材料力學(xué)性能簡(jiǎn)介：
biomomentum多軸機(jī)械測(cè)試儀Mach-1材料力學(xué)性能是指材料在不同環(huán)境(溫度、介質(zhì)、濕度)下，承受各種外加載荷(拉伸、壓縮、彎曲、扭轉(zhuǎn)、沖擊、交變應(yīng)力等)時(shí)所表現(xiàn)出的力學(xué)特征。
可以放進(jìn)標(biāo)準(zhǔn)培養(yǎng)箱里進(jìn)行培養(yǎng)；
biomomentum多軸機(jī)械測(cè)試儀Mach-1測(cè)試意義及適用范圍：
材料力學(xué)性能可以應(yīng)用到生產(chǎn)的任何階段，從測(cè)試原材料質(zhì)量直到檢查制成品的耐用性。 測(cè)試可對(duì)廣泛多樣的生物樣品、材料和產(chǎn)品進(jìn)行，包括軟組織、軟骨組織、皮膚組織、凝膠組織、高分子材料、生物產(chǎn)品、醫(yī)學(xué)鑒定和水凝膠等。力學(xué)性能測(cè)試可幫助企業(yè)向客戶證明其產(chǎn)品的力學(xué)性能、穩(wěn)定性和安性，從而獲得基礎(chǔ)數(shù)據(jù)和競(jìng)爭(zhēng)勢(shì)。
1、多功能、多軸向，適用樣品范圍廣：
1.1、從骨等硬組織材料到腦組織、眼角膜等極軟的組織材料
1.2、從粗的椎間盤(pán)的樣品到極細(xì)的單纖維絲
2、力學(xué)類(lèi)型測(cè)試分析功能齊全：
2.1、模塊化集成壓縮、張力、剪切、摩擦、扭轉(zhuǎn)、穿刺、摩擦和非平面壓痕、3D厚度、3D表面輪廓等各種力學(xué)類(lèi)型支持,微觀結(jié)構(gòu)表征及動(dòng)態(tài)力學(xué)分析研究
2.2、多物理場(chǎng)耦合加載測(cè)試