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>

Fabrication and Mechanical Property Assessment of Fiber Composite Laminates

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>
		</tr>
		<tr>
			<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%。

Fiber reinforced polymer composite (FRP) is a type of high-strength material manufactured by mixing fiber reinforcement and polymer matrixes1,2,3. It is widely used in the aerospace4,5,6, construction7,8, automotive9, and marine10,11 industries due to its low density, high specific stiffness and strength, fatigue properties, and excellent corrosion resistance. Common synthetic fibers include carbon fibers, glass fibers, and aramid fibers12. Glass fiber was chosen for investigation in this paper. Compared to traditional steel, glass fiber reinforcement composite laminates (GFRPs) are lighter, with less than one-third of the density, but can achieve a higher specific strength than steel.
The preparation process of FRP includes vacuum-assisted resin transfer molding (VARTM)13, filament winding (FW)14, and prepreg molding, in addition to many other advanced fabrication processes15,16,17,18. Compared to other preparation processes, the wet hand lay-up/vacuum bag (WLVB) process has several advantages, including simple equipment requirements and uncomplicated process technology, and the products are not limited by size and shape. This process has a high degree of freedom and can be integrated with metal, wood, plastic, or foam.
The principle of the WLVB process is to apply greater forming pressure through vacuum bags to enhance the mechanical properties of the prepared laminates; the production technology of this process is easy to master, making it an economical and simple composite material preparation process. This process is completely manual, and it is greatly influenced by the skills of preparation personnel. Therefore, the products are prone to defects such as voids and uneven thickness, leading to unstable qualities and mechanical properties of the laminate. Hence, it is necessary to describe the WLVB process in detail, finely control steps, and quantify material proportion, in order to obtain a high stability of mechanical properties of laminates.
Most researchers have studied the quasi-static19,20,21,22,23 and dynamic behavior24,25,26,27,28, as well as the property modification29,30 of composite materials. The volume fraction ratio of fiber to matrix plays a crucial role in mechanical properties of FRP laminate. In an appropriate range, a higher volume fraction of fiber can improve the strength and stiffness of FRP laminate. Andrew et al.31 investigated the effect of fiber volume fraction on the mechanical properties of specimens prepared by the fused deposition modeling (FDM) additive manufacturing process. The results showed that when the fiber volume fraction was 22.5%, the tensile strength efficiency reached its maximum, and a slight improvement in strength was observed as the fiber volume fraction reached 33%. Khalid et al.32 studied the mechanical properties of continuous carbon fiber (CF)-reinforced 3D-printed composites with diverse fiber volume fractions, and the results showed that both tensile strength and stiffness were improved with the rise in fiber content. Uzay et al.33 investigated the effects of three fabrication methods-hand lay-up, compression molding, and vacuum bagging-on the mechanical properties of carbon fiber-reinforced polymer (CFRP). The fiber volume fraction and void of the laminates were measured, tensile and bending tests were conducted. The experiments showed that the higher the fiber volume fraction, the better the mechanical properties.
Voids are one of the most common defects in FRP laminate. Voids reduce the mechanical properties of composite materials, such as strength, stiffness, and fatigue resistance34. The stress concentration generated around the voids promotes the propagation of micro-cracks and reduces the interface strength between reinforcement and matrix. Internal voids also accelerate the moisture absorption of FRP laminate, resulting in interface debonding and performance degradation. Therefore, the existence of internal voids affects the reliability of composite and restricts their wide application. Zhu et al.35 investigated the influence of void content on the static interlaminar shear strength properties of CFRP composite laminates, and found that a 1% increase in void content ranging from 0.4% to 4.6% led to a 2.4% deterioration in interlaminar shear strength. Scott et al.36 presented the effect of voids on damage mechanism in CFRP composite laminates under hydrostatic loading using computed tomography (CT), and found that the number of voids is 2.6-5 times the number of randomly distributed cracks.
High-quality and reliable FRP laminates can be manufactured by using an autoclave. Abraham et al.37 manufactured low-porosity, high-fiber content laminates by placing a WLVB assembly in an autoclave with a pressure of 1.2 MPa for curing. Nevertheless, the autoclave is a large and expensive piece of equipment, resulting in considerable manufacturing costs. Although the vacuum-assisted resin transfer process (VARTM) has been in use for a long time, it has a limit in terms of the time cost, a more complicated preparation process, and more disposable consumables such as diversion tubes and diversion media. Compared with the WL process, the WLVB process compensates for insufficient molding pressure through a low-cost vacuum bag, absorbing excess resin from the system to increase the fiber volume fraction and reduce the internal pore content, thereby greatly improving the mechanical properties of the laminate.
This study explores the differences between the WL process and the WLVB process, and details the meticulous process of the WLVB process. The fiber volume content of laminates was calculated by the formula method, and the results showed that the fiber volume content of WL laminates was 42.04%, while that of WLVB laminates was 57.82%, increasing by 15.78%. The mechanical properties of laminates were characterized by tensile and impact tests. The experimental results revealed that with the WLVB process, the strength and modulus of the laminates were enhanced by 17.4% and 16.35%, respectively, and the specific absorbed energy was increased by 19.48%.

Author Spotlight: Enhancing Fiber Composite Laminate Quality with the Wet Hand Lay-Up/Vacuum Bag Process 

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

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

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。

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。

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

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1.1K 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: Author Spotlight: Enhancing Fiber Composite Laminate Quality with the Wet Hand Lay-Up/Vacuum Bag Process 

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the forming pressure, the mass fraction of fiber is reduced and lots of air bubbles are trapped inside, resulting in low-quality laminates (low stiffness and strength). The wet hand lay-up/vacuum bag (WLVB) process for the fabrication of composite laminates is based on the traditional wet hand lay-up process, using a vacuum bag to remove air bubbles and provide pressure, and then carrying out the heating and curing process. 
Compared with the traditional hand lay-up process, laminates manufactured by the WLVB process show superior mechanical properties, including better strength and stiffness, higher fiber volume fraction, and lower void volume fraction, which are all benefits for composite laminates. This process is completely manual, and it is greatly influenced by the skills of the preparation personnel. Therefore, the products are prone to defects such as voids and uneven thickness, leading to unstable qualities and mechanical properties of the laminate. Hence, it is necessary to finely describe the WLVB process, finely control steps, and quantify material ratios, in order to ensure the mechanical properties of laminates. 
This paper describes the meticulous process of the WLVB process for preparing woven plain patterned glass fiber reinforcement composite laminates (GFRPs). The fiber volume content of laminates was calculated using the formula method, and the calculated results showed that the fiber volume content of WL laminates was 42.04%, while that of WLVB laminates was 57.82%, increasing by 15.78%. The mechanical properties of the laminates were characterized using tensile and impact tests. The experimental results revealed that with the WLVB process, the strength and modulus of the laminates were enhanced by 17.4% and 16.35%, respectively, and the specific absorbed energy was increased by 19.48%.

This paper describes a fabrication process for fiber-reinforced polymer matrix composite laminates obtained using the wet hand lay-up/vacuum bag method.

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﻿Fabrication of Glass Fiber-Reinforced Polymer (GFRP) Composite Laminates by Wet Hand Lay-Up/Vacuum Bag (WLVB) Method

Fabrication of Glass Fiber-Reinforced Polymer (GFRP) Composite Laminates by Wet Hand Lay-Up/Vacuum Bag (WLVB) Method  

Begin by heating the glass fiber fabric at 60 degrees Celsius for eight hours. Then, paste an isolation film on the acrylic sheet to prevent the resin from bonding. Position the mold in the laying area.Gently mix the resin and hardener for five minutes before placing it in a vacuum chamber to remove air bubbles. Place a non-porous release film on the mold and secure it with tape. Then, lay one Peel Ply on the non-porous release film.Pour epoxy resin on the film and evenly distribute it throughout using a scraper. Next, ply the first fiber fabric on the resin. Roll the fabric with a naked roller to ensure bubble removal and complete resin infiltration into the fabric.Again, pour and evenly spread the resin on the fabric using a scraper and continue till all the fabric has been used. Place a Peel Ply on the fabric and manually remove air bubbles by scraping in one direction. Lay a perforated release film followed by a breather fabric.Position the suction channel and breathable pad to one side. Secure a circular heat-resistant tape with an acrylic sheet outside the mold and attach the vacuum bag at the top of the device to create a closed space. Apply vacuum for 10 hours at room temperature, then switch off the vacuum pump and maintain quiescence for 14 hours.Cure the laminates completely at 80 degrees Celsius for 16 hours before measuring the fiber volume fraction. Comparison of laminates fabricated by the wet hand layup method with and without the vacuum bag process revealed that the vacuum bag assistance, the fiber volume fraction of the laminates increased by 15.78%and their average thickness reduced to 2.11 millimeters.

湿手糊/真空袋（WLVB）法制备玻璃纤维增强聚合物（GFRP）复合层合板

Impact Property Characterization of Glass Fiber-Reinforced Polymer (GFRP) Composite Laminates

To begin the impact test of glass fiber reinforced polymer or GFRP composite laminates. Cut a set of 150 millimeter by 100 millimeter GFRP samples using a high precision cutting machine. Record the weight and size of each sample.Then mark the positions of the samples using positioning nails in their centers that the impactor can contact for every test. Fix the sample onto the impact support fixture using four rubber tips. Power on the drop hammer testing machine to conduct the impact test using a drop weight impact tower.After connecting it to the controller click home to do the beam reset and then click before test. Input the measurement thickness as 2.1 or 2.5 millimeters for WLVB or WL samples respectively. Set the additional mass to two kilograms and the impact energy to 10 joules.Click start to initiate the experiment. Record the impact response data such as force, deflection, and energy history. Remove the sample and document its morphology after the impact.Finally, calculate and compare the data of each sample. Great repeatability of the impact test was evident from the obtained force and absorbed energy curves of samples fabricated by WLVB and WL methods. The force time curve represented a typical non-piercing curve having a sine wave-like shape.The absorbed energy value increased first with the laminate absorbing and converting the impactor's kinetic energy into its internal energy. And then the value decreased over time as the laminate released elastic energy to rebound the impactor. The specific absorbed energy of the WLVB sample was larger than that of the WL sample.The WLVB laminates absorbed 19.48%more specific energy compared to the WL ones. Further, the higher impact energy absorption capacity of WLVB samples was confirmed by their relatively smaller damaged area.