作者感谢国家重点研发计划（编号:2022YFB3706503）和深圳市自然科学基金稳定支持计划计划（编号:20220815133826001）的资助。

1、材料准备
<ol><li>用剪刀剪下八块 300 毫米 x 300 毫米的玻璃纤维编织布。先用胶带粘住切口，以防止纤维丝脱落。 注意: 在切割织物时，请戴上口罩和手套，以防止手指刺伤和吸入细丝。不仅有玻璃纤维编织物，还有单向织物和其他类型的纤维，如碳纤维和芳纶纤维。</li>
	<li>按10:3的质量比称出环氧树脂260g和硬化剂78g。 注:纤维织物与树脂体系的比例建议为每平方米单层纤维织物360克环氧树脂体系。</li>
</ol>2.制造过程
注: 图 1 显示了用于手糊工艺的复合层压板的制造示意图，如第 2 节所示。
<ol><li>WLVB型<ol>
<li>将织物放入60°C的烘箱中8小时。</li>
		<li>在亚克力板上粘贴隔离膜，防止树脂粘结。</li>
		<li>将模具放在铺设区域。</li>
		<li>将树脂和硬化剂缓慢混合5min，然后放入真空室中，抽出里面的气泡。</li>
		<li>将无孔离型膜铺在模具上，并用胶带固定。</li>
		<li>在无孔离型膜上铺设一层剥离层。</li>
		<li>倒入环氧树脂，用刮刀将树脂均匀地分布在整个薄膜上。</li>
		<li>铺上第一层纤维织物，用裸辊卷起，确保树脂充分渗入织物，气泡被挤出，然后倒入树脂，用刮刀将树脂刮均匀。</li>
		<li>重复步骤 2.1.7 和 2.1.8，直到用完所有结构。</li>
		<li>在织物上铺上一层剥离层，然后手动挤出气泡。</li>
		<li>依次铺设一层穿孔离型膜和一块透气织物。</li>
		<li>将吸道和透气垫放在一侧。</li>
		<li>在模具外贴上一圈带有亚克力板的耐热胶带，然后用胶带将真空袋贴在周围，形成一个封闭的空间。</li>
		<li>打开真空泵，在室温下按压1巴压力10小时。然后，关闭真空泵并保持静止14小时。</li>
		<li>将层压板放入80°C的烘箱中16小时以完全固化。</li>
		<li>使用公式 （1-3）38,39 测量纤维体积分数。 <img alt="Equation 1" src="/files/ftp_upload/65376/65376eq01.jpg" style="margin: auto;">（一） <img alt="Equation 2" src="/files/ftp_upload/65376/65376eq02.jpg" style="margin: auto;">（二） <img alt="Equation 3" src="/files/ftp_upload/65376/65376eq03.jpg" style="margin: auto;">（三） n是层压板的层数，ρ纤维是制造商提供的纤维织物的面密度，A纤维是层压板的面积，m纤维是 纤维织物的质量，m总计是层压板的质量，ρ环氧树脂是环氧树脂的密度，v环氧树脂和v 总和v分别是环氧树脂和层压板的体积，是纤维体积分数。</li>
	</ol>
</li>
	<li>西城<ol>
<li>将织物放入60°C的烘箱中8小时。</li>
		<li>将树脂和固化剂缓慢混合5分钟，然后将其放入真空室中以抽出内部的气泡。</li>
		<li>将无孔离型膜铺在模具上，并用胶带固定。</li>
		<li>在无孔离型膜上铺设一层剥离层。</li>
		<li>倒入环氧树脂，用刮刀将树脂均匀地分布在整个薄膜上。</li>
		<li>铺上第一层纤维织物，用裸辊卷起，确保树脂充分渗入织物，气泡被挤出，然后倒入树脂，用刮刀将树脂刮均匀。</li>
		<li>重复步骤 2.2.5 和 2.2.6，直到所有结构都用完。</li>
		<li>在织物上铺上一层剥离层，然后手动挤出气泡。</li>
		<li>依次铺设一层穿孔离型膜、一层透气织物和一层无孔离型膜。</li>
		<li>将一块与纤维织物大小相同的铝板放在上面。</li>
		<li>在室温下保持静止14小时。</li>
		<li>将层压板放入80°C的烘箱中16小时以完全固化。</li>
	</ol>
</li>
</ol>3. 冲击特性的表征
注:复合材料层压板的冲击试验方法有很多种。在低速冲击条件下，常用的方法是落锤冲击试验，而在高速或超高速冲击条件下，常用的方法是子弹冲击法。在这项研究中，应用了落锤冲击试验。设备如图 2所示。
<ol><li>根据 ASTM D7136 标准，使用高精度切割机从 GFRP 切割一组 150 mm x 100 mm 样品进行冲击测试。</li>
	<li>测量每个样品的重量和大小。</li>
	<li>在每次测试中撞击器可以接触的样品中心使用定位钉固定样品的位置。</li>
	<li>用四个橡胶尖端将样品固定在冲击支撑夹具上。</li>
	<li>使用 10 J 能量水平的落锤冲击塔进行冲击测试。打开落锤试验机，点击连接，将控制器与下拉菜单 连接 ，然后点击 首页|好测试前。将冲击能量设置为 10 J，将附加质量设置为 2 kg。输入测量厚度，WLVB 样品为 2.1 mm，WL 样品为 2.5 mm，以确定撞击器的高度，然后单击"开始" 开始 实验。</li>
	<li>记录冲击响应数据，包括力、挠度和能量历史。</li>
	<li>取出样品。记录撞击后样品的形态。</li>
	<li>重复冲击试验五次，以确保结果的可重复性。</li>
	<li>计算和比较样本数据。</li>
</ol>4. 拉伸性能的表征
<ol><li>根据 ASTM D3039 标准，使用带有金刚石切割机的高精度切割机从层压板上切割一组 250 mm x 25 mm 的样品进行拉伸测试。</li>
	<li>用游标卡尺测量每个样品的大小。</li>
	<li>使用环氧树脂粘合剂在样品两端粘接四个 50 mm x 25 mm x 2 mm 的铝片，以避免应力集中。</li>
	<li>在样品正面喷上一层薄薄的白色油漆，然后喷上黑色斑点。</li>
	<li>将试样放在拉力试验机夹具的中心，设置图像采集系统， 如图3所示。</li>
	<li>为确保应变数据的准确性，请改变样品的位置，使其位于相机拍摄区域的中间和垂直位置。此外，调整相机焦距和曝光率，以确保清晰记录样品上的斑点。</li>
	<li>进行拉伸试验。单击 CONFIGURE TEST。将测试速度设置为 0.5 mm/min。单击"标本数据"。输入样品的测量宽度和厚度。单击"开始"，然后单击"接受当前位置"。记录加载时间数据。</li>
	<li>取出样品。记录拉伸试验后试样的形貌。</li>
	<li>重复拉伸试验五次，以确保结果的重复性。</li>
	<li>在拉伸试验过程中，使用数字图像相关（DIC）软件测量样品的标称应变。</li>
	<li>单击 "长度缩放 图像"以校准像素的长度，单击"参考图像"，然后选择第一个图像作为 参考图像。单击"变形图像"，然后选择剩余图像作为 变形图像 。单击 "绘图工具"|"选择矩形以选择 测量区域。单击引伸计并将引 伸计 的长度设置为 100 mm，然后单击 "处理"|"启动关联。</li>
	<li>将荷载除以横截面积得到公称应力。</li>
	<li>将DIC测量的标称应变和拉伸试验机的标称应力结合起来。</li>
	<li>选择应变-应力曲线线性段的斜率作为弹性模量。选择拉力-时间曲线的峰值作为强度。</li>
	<li>比较样品的弹性模量和强度。</li>
</ol>

纤维复合材料层压板的制造和机械性能评估

作者没有任何利益冲突。

本文重点介绍了两种不同的低成本手糊法制造工艺。因此，本文选择了两种制造工艺进行仔细描述，它们更简单、更容易掌握、投资成本较低，并且适合在实验室和小规模工厂进行材料改性生产。在层压板的固化过程中，高固结压力在制造高质量的层压板中起着重要作用。在没有足够外部压力的情况下采用传统的WL工艺会导致树脂体积分数过高。树脂体积大是降低层压板机械性能的主要因素之一?...

纤维增强聚合物复合材料（FRP）是一种由纤维增强材料和聚合物基体混合而成的高强度材料1,2,3。由于其密度低、比刚度和强度高、疲劳性能好、耐腐蚀性好等特点，被广泛应用于航空航天4、5、6、建筑7、8、汽车9、船舶101等行业。常见的合成纤维包括碳纤维、玻璃纤维和芳纶纤维12。本文选择玻璃纤维进行研究。与传统钢相比，玻璃纤维增强复合层压板（GFRPs）更轻，密度不到三分之一，但可以达到比钢更高的比强度。
FRP的制备工艺包括真空辅助树脂传递模塑（VARTM）13、纤维缠绕（FW）14和预浸料成型，以及许多其他先进的制造工艺15,16,17,18。与其他制备工艺相比，湿手糊/真空袋（WLVB）工艺具有设备要求简单、工艺技术不复杂等优点，产品不受尺寸和形状的限制。该工艺具有高度的自由度，可以与金属、木材、塑料或泡沫集成。
WLVB工艺的原理是通过真空袋施加更大的成型压力，以增强制备的层压板的机械性能;该工艺的生产工艺易于掌握，是一种经济、简单的复合材料制备工艺。这个过程完全是手工的，受准备人员技能的影响很大。因此，产品容易出现空隙和厚度不均匀等缺陷，导致层压板的质量和机械性能不稳定。因此，有必要详细描述WLVB工艺，精细控制步骤，量化材料比例，以获得高稳定性的层压板机械性能。
大多数研究人员研究了复合材料的准静态19,20,21,22,23和动态行为24,25,26,27,28，以及性能改性29,30。纤维与基体的体积分数比对玻璃钢层压板的力学性能起着至关重要的作用。在适当的范围内，较高的纤维体积分数可以提高玻璃钢层压板的强度和刚度。Andrew等[31]研究了纤维体积分数对熔融沉积成型（FDM）增材制造工艺制备的试样力学性能的影响。结果表明，当纤维体积分数为22.5%时，拉伸强度效率达到最大，当纤维体积分数达到33%时，强度略有提高。Khalid等[32]研究了具有不同纤维体积分数的连续碳纤维（CF）增强3D打印复合材料的力学性能，结果表明，拉伸强度和刚度均随着纤维含量的增加而提高。Uzay等[33]研究了手糊、压缩成型和真空袋3种制备方法对碳纤维增强聚合物（CFRP）力学性能的影响。测量层压板的纤维体积分数和空隙，进行拉伸和弯曲试验。实验表明，纤维体积分数越高，力学性能越好。
空隙是玻璃钢层压板中最常见的缺陷之一。空隙会降低复合材料的机械性能，例如强度、刚度和抗疲劳性34.空隙周围产生的应力集中促进了微裂纹的扩展，降低了钢筋与基体之间的界面强度。内部空隙还会加速FRP层压板的吸湿性，导致界面脱粘和性能下降。因此，内部空隙的存在影响了复合材料的可靠性，限制了复合材料的广泛应用。Zhu等[35 ]研究了空隙率对CFRP复合材料层合板静态层间剪切强度性能的影响，发现空隙率在0.4%-4.6%之间增加1%会导致层间剪切强度下降2.4%。Scott等[36 ]利用计算机断层扫描（CT）研究了静水载荷作用下CFRP复合材料层合板空隙对损伤机理的影响，发现空隙数量是随机分布裂纹数量的2.6-5倍。
使用高压釜可以制造高质量和可靠的FRP层压板。Abraham 等人 37 通过将 WLVB 组件放置在压力为 1.2 MPa 的高压釜中进行固化来制造低孔隙率、高纤维含量的层压板。然而，高压灭菌器是一种大型且昂贵的设备，导致相当大的制造成本。真空辅助树脂转移工艺（VARTM）虽然已经使用了很长时间，但在时间成本、制备工艺更复杂、导流管、导流介质等一次性耗材较多等方面存在局限性。与WL工艺相比，WLVB工艺通过低成本的真空袋补偿成型压力不足，从系统中吸收多余的树脂，以增加纤维体积分数并降低内部孔隙含量，从而大大提高层压板的机械性能。
本文探讨了WL工艺与WLVB工艺的区别，并详细介绍了WLVB工艺的细致工艺。采用公式法计算层合板的纤维体积含量，结果表明，WL层合板的纤维体积含量为42.04%，而WLVB层合板的纤维体积含量为57.82%，提高了15.78%。层压板的机械性能通过拉伸和冲击试验进行表征。实验结果表明，采用WLVB工艺，层合板的强度和模量分别提高了17.4%和16.35%，比吸收能提高了19.48%。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>breather fabric</td>
			<td>Easy composites</td>
			<td>BR180</td>
			<td></td>
		</tr>
		<tr>
			<td>drop-weight impact testing machine</td>
			<td>Instron</td>
			<td>9340</td>
			<td></td>
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			<td>Epoxy matrix</td>
			<td>Axson Technologies</td>
			<td>5015/5015</td>
			<td></td>
		</tr>
		<tr>
			<td>glass fiber</td>
			<td>Weihai Guangwei Composites</td>
			<td>W-9311</td>
			<td></td>
		</tr>
		<tr>
			<td>non-porous release film</td>
			<td>Easy composites</td>
			<td>R240</td>
			<td></td>
		</tr>
		<tr>
			<td>Peel ply&#160;</td>
			<td>Sino Composite</td>
			<td>CVP200</td>
			<td></td>
		</tr>
		<tr>
			<td>perforated released film</td>
			<td>Easy composites</td>
			<td>R120-P3</td>
			<td></td>
		</tr>
		<tr>
			<td>test machine</td>
			<td>ZwickRoell</td>
			<td>250kN</td>
			<td></td>
		</tr>
		<tr>
			<td>vacuum film</td>
			<td>Easy composites</td>
			<td>GVB200</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring the mechanical properties of glass fiber reinforcement polymer composite laminates obtained by different fabrication processes

传统的湿手糊工艺（WL）已广泛应用于纤维复合材料层压板的制造。然而，由于成型压力不足，纤维的质量分数降低，内部滞留大量气泡，导致层压板质量低下（刚度和强度低）。用于制造复合层压板的湿手糊/真空袋（WLVB）工艺是在传统湿手糊工艺的基础上，使用真空袋去除气泡并提供压力，然后进行加热和固化过程。 
与传统的手糊工艺相比，WLVB工艺制造的层压板表现出优异的机械性能，包括更好的强度和刚度、更高的纤维体积分数和更低的空隙体积分数，这些都是复合材料层压板的优势。这个过程完全是手工的，受准备人员技能的影响很大。因此，产品容易出现空隙和厚度不均匀等缺陷，导致层压板的质量和机械性能不稳定。因此，有必要详细描述WLVB工艺，精细控制步骤，量化材料比例，以确保层压板的机械性能。 
本文介绍了WLVB工艺制备编织平纹玻璃纤维增强复合材料层合板（GFRPs）的细致工艺。采用公式法计算层合板的纤维体积含量，计算结果显示，WL层合板的纤维体积含量为42.04%，而WLVB层合板的纤维体积含量为57.82%，提高了15.78%。使用拉伸和冲击测试表征层压板的机械性能。实验结果表明，采用WLVB工艺，层合板的强度和模量分别提高了17.4%和16.35%，比吸收能提高了19.48%。

表 1 显示了样品的纤维体积分数、平均厚度和制造工艺。G8-WLVB 和 G8-WL 分别代表了由 8 层玻璃织物组成的层压板，这些层压板分别采用和不采用真空袋工艺，采用湿手糊法制造。显然，在真空袋的辅助下，层压板的纤维体积分数增加了15.78%，平均厚度减少了16.27%。
WLVB和WL试样拉伸试验得到的应变-应力曲线如图 4所示。纵轴显示由力除以横截...

Watch this Scientific Journal Video about Enhancing Fiber Composite Laminate Quality with the Wet Hand Lay-Up/Vacuum Bag Process at JoVE.com

作者聚焦:使用湿法手糊/真空袋工艺提高纤维复合材料层压板质量 

本文介绍了使用湿手糊/真空袋法获得的纤维增强聚合物基复合材料层合板的制造工艺。

测量通过不同制造工艺获得的玻璃纤维增强聚合物复合层压板的机械性能

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the ...

我们的研究重点是提高纤维复合材料的界面韧性和受损电阻。我们正试图通过加入纳米颗粒来提高纤维复合材料的抵抗力。纤维复合材料制造中最常见的挑战之一是缺乏可重复性。通过精确控制制造深度和量化材料比例，我们可以获得具有非常稳定的机械性能的层压板。这种方法确保了不同批次的测试结果具有高度可重复性。用于制造复合材料层压板的 eWLB 工艺使用真空袋去除气泡。与其他工艺相比，该工艺具有很多优点。它需要简单的设备，涉及的工艺技术并不复杂，产品也不受尺寸或形状的限制。

measuring-mechanical-properties-glass-fiber-reinforcement-polymer

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JoVE Core

JoVE Journal

Civil Engineering

Engineering

Unit 1

Measuring the Mechanical Properties of Glass Fiber Reinforcement Polymer Composite Laminates Obtained by Different Fabrication Processes

Strength of Concrete

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1.8K 次观看.  Southern University of Science and Technology. 我们的研究重点是提高纤维复合材料的界面韧性和受损电阻。我们正试图通过加入纳米颗粒来提高纤维复合材料的抵抗力。纤维复合材料制造中最常见的挑战之一是缺乏可重复性。通过精确控制制造深度和量化材料比例，我们可以获得具有非常稳定的机械性能的层压板。这种方法确保了不同批次的测试结果具有高度可重复性。用于制造复合材料层压板的 eWLB 工艺使用真?...

视频: 作者聚焦:使用湿法手糊/真空袋工艺提高纤维复合材料层压板质量 

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

一个测试平台为聚合物的耐久性研究，并在同期Hygrothermo机械刺激纤维增强聚合物复合材料

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

科研

工程学

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

电活性聚合物纳米粒子参展光热特性

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional component that should have high electrical conductivity, high mechanical properties, and high productivity.
In this regard, a carbon fiber/epoxy resin composite can be an ideal material to replace the conventional graphite bipolar plate, which often leads to the catastrophic failure of the entire system because of its inherent brittleness. Though the carbon/epoxy composite has high mechanical properties and is easy to manufacture, the electrical conductivity in the through-thickness direction is poor because of the resin-rich layer that forms on its surface. Therefore, an expanded graphite coating was adopted to solve the electrical conductivity issue. However, the expanded graphite coating not only increases the manufacturing costs but also has poor mechanical properties.
In this study, a method to expose fibers on the composite surface is demonstrated. There are currently many methods that can expose fibers by surface treatment after the fabrication of the composite. This new method, however, does not require surface treatment because the fibers are exposed during the manufacture of the composite. By exposing bare carbon fibers on the surface, the electrical conductivity and mechanical strength of the composite are increased drastically.

A protocol to expose bare fibers on the composite surface by eliminating resin rich area is presented. The fibers are exposed during fabrication of the composites, not by the post surface treatment. The exposed carbon composites exhibit high electrical conductivity in the through-thickness direction and high mechanical property.

一种新的复合制备方法的实验实现: 用软层法对复合材料表面裸露纤维进行曝光

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional ...

Magnet Assisted Composite Manufacturing: A Flexible New Technique for Achieving High Consolidation Pressure in Vacuum Bag/Lay-Up Processes

This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed magnet assisted composite manufacturing (MACM) technique. In this technique, permanent magnets are utilized to apply a sufficiently high consolidation pressure during the curing stage. To enhance the intensity of the magnetic field, and thus, to increase the magnetic compaction pressure, the magnets are placed on a magnetic top plate. First, the entire procedure of preparing the composite lay-up on a magnetic bottom steel plate using the conventional wet lay-up vacuum bag process is described. Second, placement of a set of Neodymium-Iron-Boron permanent magnets, arranged in alternating polarity, on the vacuum bag is illustrated. Next, the experimental procedures to measure the magnetic compaction pressure and volume fractions of the composite constituents are presented. Finally, methods used to characterize microstructure and mechanical properties of composite laminates are discussed in detail. The results prove the effectiveness of the MACM method in improving the quality of wet lay-up vacuum bag laminates. This method does not require large capital investment for tooling or equipment and can also be used to consolidate geometrically complex composite parts by placing the magnets on a matching top mold positioned on the vacuum bag.

A new technique for applying consolidation pressure on the vacuum bag lay-up to fabricate composite laminates is described. The goal of this protocol is to develop a simple, cost-effective technique to improve the quality of laminates fabricated by the wet lay-up vacuum bag method.

磁铁辅助复合制造: 真空袋/糊化过程中实现高固结压力的一种柔性新技术

This work demonstrates a protocol to improve the quality of composite laminates fabricated by wet lay-up vacuum bag processes using the recently developed ...

One-Step Approach to Fabricating Polydimethylsiloxane Microfluidic Channels of Different Geometric Sections by Sequential Wet Etching Processes

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. Customized channel layout designs are necessary for specific functions and integrated performance of microfluidic devices in numerous biomedical and chemical applications (e.g., cell culture, biosensing, chemical synthesis, and liquid handling). Owing to the nature of molding approaches using silicon wafers with photoresist layers patterned by photolithography as master molds, the microfluidic channels commonly have regular cross sections of rectangular shapes with identical heights. Typically, channels with multiple heights or different geometric sections are designed to possess particular functions and to perform in various microfluidic applications (e.g., hydrophoresis is used for sorting particles and in continuous flows for separating blood cells6,7,8,9). Therefore, a great deal of effort has been made in constructing channels with various sections through multiple-step approaches like photolithography using several photoresist layers and assembly of different PDMS thin sheets. Nevertheless, such multiple-step approaches usually involve tedious procedures and extensive instrumentation. Furthermore, the fabricated devices may not perform consistently and the resulted experimental data may be unpredictable. Here, a one-step approach is developed for the straightforward fabrication of microfluidic channels with different geometric cross sections through PDMS sequential wet etching processes, that introduces etchant into channels of planned single-layer layouts embedded in PDMS materials. Compared to the existing methods for manufacturing PDMS microfluidic channels with different geometries, the developed one-step approach can significantly simplify the process to fabricate channels with non-rectangular sections or various heights. Consequently, the technique is a way of constructing complex microfluidic channels, which provides a fabrication solution for the advancement of innovative microfluidic systems.

Several methods are available for the fabrication of channels of non-rectangular sections embedded in polydimethylsiloxane microfluidic devices. Most of them involve multistep manufacturing and extensive alignment. In this paper, a one-step approach is reported for fabricating microfluidic channels of different geometric cross sections by polydimethylsiloxane sequential wet etching.

连续湿法刻蚀法制作不同几何断面烷微流控通道的一步法

Polydimethylsiloxane (PDMS) materials are substantially exploited to fabricate microfluidic devices by using soft lithography replica molding techniques. ...

Design and Fabrication of an Optical Fiber Made of Water

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with solid-cladding devices, capillary oscillations are not restricted, allowing the fiber walls to move and vibrate. The fiber is constructed by a high direct current (DC) voltage of several thousand volts (kV) between two water reservoirs that creates a floating water thread, known as a water bridge. Through the choice of micropipettes, it is possible to control the maximal diameter and length of the fiber. Optical fiber couplers, at both sides of the bridge, activate it as an optical waveguide, allowing researchers to monitor the water fiber capillary body waves through transmission modulation and, therefore, deducing changes in surface tension.
Co-confining two important wave types, capillary and electromagnetic, opens a new path of research in the interactions between light and liquid-wall devices. Water-walled microdevices are a million times softer than their solid counterparts, accordingly improving the response to minute forces.

This protocol describes the design and manufacture of a water bridge and its activation as a water fiber. The experiment demonstrates that capillary resonances of the water fiber modulate its optical transmission.

一种水上光纤的设计与制造

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with ...

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, where the yarns in each layer are oriented parallel to each other and held in place using binder resins and thin polymer films. The armor is constructed by stacking the unidirectional layers in different orientations. To date, only very preliminary work has been performed to characterize the ageing of the binder resins used in unidirectional laminates and the effects on their performance. For example, during the development of the conditioning protocol used in the National Institute of Justice Standard-0101.06, UD laminates showed visual signs of delamination and reductions in V50, which is the velocity at which half of the projectiles are expected to perforate the armor, after ageing. A better understanding of the material property changes in UD laminates is necessary to comprehend the long-term performance of armors constructed from these materials. There are no current standards recommended for mechanically interrogating unidirectional (UD) laminate materials. This study explores methods and best practices for accurately testing the mechanical properties of these materials and proposes a new test methodology for these materials. Best practices for ageing these materials are also described.

The goal of the study was to develop protocols to prepare consistent specimens for accurate mechanical testing of high-strength aramid or ultra-high-molar-mass polyethylene-based flexible unidirectional composite laminate materials and to describe protocols for performing artificial ageing on these materials.

柔性单向复合层压板的切割程序、拉伸测试和老化

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...

Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on an optical lever method is designed. A millimetric cantilever is used as a force sensitive component in the measurement system. Firstly, the force sensitivity of the optical lever is calibrated using electrostatic force, which is the critical step in measuring interaction force. Secondly, three super-hydrophobic substrates with different grid fractions are prepared with nanoparticles and copper grids. Finally, the interaction forces between droplets and super-hydrophobic substrates with different grid fractions are measured by the system. This method can be used to measure the force on the scale of sub-micronewton with a resolution on the scale of nanonewton. The in-depth study of the contact process of droplets and super-hydrophobic structures can help to improve the production efficiency in coating, film and printing. The force measurement system designed in this paper can also be used in other fields of microforce measurement.

The protocol aims to investigate the interaction between droplets and super-hydrophobic substrates in the air. This includes calibrating the measurement system and measuring the interaction force at super-hydrophobic substrates with different grid fractions.

用光学杠杆方法测量液滴和超疏水基板之间的相互作用力

The goal of this paper is to investigate the interaction force between droplets and super-hydrophobic substrates in the air. A measurement system based on ...

Operation of the Collaborative Composite Manufacturing (CCM) System

The automated tape placement and the automated fiber placement (AFP) machines provide a safer working environment and reduce the labor intensity of workers than the traditional manual fiber placement does. Thus, the production accuracy, repeatability and efficiency of composite manufacturing are significantly improved. However, the current AFP systems can only produce the composite components with large open surface or simple revolution parts, which cannot meet the growing interest in small complex or closed structures from industry.
In this research, by employing a 1-degree of freedom (DoF) rotational stage, a 6-RSS parallel robot, and a 6-DoF serial robot, the dexterity of the AFP system can be significantly improved for manufacturing complex composite parts. The rotational stage mounted on the parallel robot is utilized to hold the mandrel and the serial robot carries the placement head to mimic two human hands that have enough dexterity to lay the fiber to the mandrel with complex contour.
Although the CCM system increases the flexibility of composite manufacturing, it is quite time-consuming or even impossible to generate the feasible off-line path, which ensures uniform lay-up of subsequent fibers considering the constraints like singularities, collisions between the fiber placement head and mandrel, smooth fiber direction change and keeping the fiber placement head along the norm of the part&#39;s surface, etc. Moreover, due to the existing positioning error of the robots, the on-line path correction is needed. Therefore, the on-line pose correction algorithm is proposed to correct the paths of both parallel and serial robots, and to keep the relative path between the two robots unchanged through the visual feedback when the constraint or singularity problems in the off-line path planning occur. The experimental results demonstrate the designed CCM system can fulfill the movement needed for manufacturing a composite structure with Y-shape.

Operation of the Collaborative Composite Manufacturing CCM System

A collaborative composite manufacturing system is developed for robotic lay-up of composite laminates using the prepreg tape. The proposed system allows the production of composite laminates with high levels of geometrical complexity. The issues in the path planning, coordination of the robots and control are addressed in the proposed method.

协同复合制造 （CCM） 系统的操作

The automated tape placement and the automated fiber placement (AFP) machines provide a safer working environment and reduce the labor intensity of ...

Application of a Coupling Agent to Improve the Dielectric Properties of Polymer-Based Nanocomposites

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer matrix by adding 3-aminopropyltriethoxysilane (KH550) as a coupling agent during the fabrication process of BaTiO3-P(VDF-CTFE) nanocomposites through solution casting. Results show that the use of KH550 can modify the surface of ceramic nanofillers; therefore, good wettability on the ceramic-polymer interface was achieved, and the enhanced energy storage performances were obtained by a suitable amount of the coupling agent. This method can be used to prepare flexible composites, which is highly desirable for the production of high-performance film capacitors. If an excessive amount of coupling agent is used in the process, the non-attached coupling agent can participate in complex reactions, which leads to a decrease in dielectric constant and an increase in dielectric loss.

Here, we demonstrate a simple and low-cost solution-casting process to improve the compatibility between the filler and the matrix of polymer-based nanocomposites using surface modified BaTiO3 fillers, which can effectively enhance the energy density of the composites.

耦合剂在提高聚合物纳米复合物介电性能方面的应用

In this work, an easy, low-cost, and widely applicable method was developed to improve the compatibility between the ceramic fillers and the polymer ...