Qualification of the Properties of New Composite Materials

与传统材料相比，复合乐动娱乐官网材料为产品制造商提供了许多潜在优势。复合材料由两种或两种以上不同的材料制成，当它们结合在一起时，比单独使用的材料更坚固，因此，复合材料的设计通常考虑到特定的用途。其广泛的好处包括增加强度，减轻重量，优越的效率，耐用性和更大的设计灵活性。由于其不导电和耐腐蚀的特性，它们还能够很好地适应恶劣、有毒的环境。

通常，复合材料将由玻璃或碳等纤维材料与聚酯、环氧树脂或乙烯基酯等基体结合而成。碳纤维增强复合材料are predominantly used in more technically onerous applications and heavily regulated industries such as aerospace, while glass-reinforced polymer composites (GRPs) are more frequently used in less technical applications such as wind technology.

航空航天部门多年来一直在使用复合材料来提高其性能。Element现在越来越多地帮助其他行业的客户将复合材料用作新应用中的关键使能材料。例如，复合材料的超轻特性为低排放电动汽车提供了巨大的优势，而耐腐蚀、具有浮力的复合材料可以改造历来使用钢材设计的石油和天然气平台。乐动娱乐官网

Determining the properties of composite materials

When any new composite material is developed, it requires much more testing than a traditional material that has been in use for many years. The properties of the new composite need to be carefully determined through qualification testing in a variety of different environmental conditions involving multiple specimens.

When manufacturing a new part using a traditional material such as a metal, very little test result data is needed to prove all the required properties that design engineers require to show the part is fit for purpose. This is because the behavior of metals is very well understood over their many years of use.

While composite materials can offer significant advantages to designers and manufacturers, composites’ material properties are, unlike metals, non-isotropic, meaning the properties are not the same in all directions. They can exhibit very different responses to applied forces, which may vary significantly depending on the load and environmental conditions to which the composite material is exposed. Therefore, it is critical to have complete confidence in how the composite material will behave during its proposed use. The only way to achieve this is by testing extensively to build up the necessary bank of test data and provide all the test data required to manufacture a new part within the prescribed safety parameters.

The composite material will have to be extensively tested by the raw material manufacturer and, once it is purchased, by the product or parts manufacturer. A raw material inspection will need to take place on arrival at the manufacturing plant to ensure it has not been affected by transportation. As composites usually only have a six-month lifecycle, if the material has not been used in production within that timeframe, it will then need to be re-qualified. The certification process required before the new product or part using the composite material can be put into production will also demand extensive testing. Finally, testing for ongoing production control purposes will also be necessary.

复合材料试验

任何新复合材料的鉴定过程将包括一系列机械和物理试验方法，以评估其强度和耐久性，并确保其适合用途。

Mechanical testing

机械试验取决于所用试样的几何形状，分为三大类：拉伸、压缩或剪切。

拉伸和压缩试验包括用于生成纯加载模式数据的普通试验、裸孔（缺口）试验和填充孔试验，这些试验用于复制材料可能需要安装可能影响材料寿命的紧固件或螺栓的寿命行为。这些测试也可用于模拟材料组件中的缺陷。Flexural testscan be utilized as an alternate or supplementary testing procedure to consolidate the tensile and compressive mechanical properties further.

剪切试验包括面内和面外两种(interlaminar) shear tests.In-plane shear (IPS) tests utilize a tensile test set up to generate shear loading in fibers oriented at +/- 45° to the direction of the test. Interlaminar shear strength tests (ILSS) are used to determine the shear strength between the lamina and can also provide information on the degree of cure in relation to the fiber-matrix adhesion.

此外，元素的断裂韧性试验show how the development of cracks or delamination can influence material properties. Mode I tests show the behavior of cracks opening and extending, while mode II tests are used to generate data on crack shear behavior and mode III on crack tearing or twisting. Additionally,compression after impact (CAI)tests are able to show the degradation of the materials’ mechanical properties after a controlled impact.

Element also provides an extensive range of other mechanical tests, including lap shear testing; climbing drum peel (CDP) testing; bearing testing; corner bend testing; and fastener pull-through testing to identify the weakest parts of a composite’s structure.

物理测试

Physical tests are critical to fully characterize a new composite material’s behavior and, unlike mechanical testing, are not dependent on the geometry of the material. Element offers the full range of physical testing required for material qualification and certification, including:

• Constituent content testing量化纤维和树脂的比例最高ss the new material. This can be determined, as well as the void content, using acid digestion or a burn off test, depending on the material to be tested.
• 动态力学分析（DMA）测试to determine the glass transition temperature using DMA (dynamic mechanical analysis) provides information on the safe upper working temperature of the part.
• Differential Scanning Calorimetry (DSC) testing以及其他热转变，用DSC表征聚合物固化程度，以及其他重要的热转变，如Tm（熔融温度）或Tc（结晶温度），如果存在的话。
• 傅里叶变换红外分析（FTIR）, a technique that uses infrared light to scan test samples and observe chemical properties.
• High Performance Liquid Chromatography (HPLC) testing识别、量化和分离复合材料的不同成分。

检查复合材料的微观结构

在鉴定新的复合材料零件时，分析材料的宏观和微观性能是很重要的。这使得识别问题，如不必要的皱纹，树脂丰富的地区，层下降，裂缝，或分层。使用这项技术，还可以量化孔隙度的百分比，也称为孔隙含量。这是关键，因为严格限制了样品的多孔性。显微镜也可以用来进一步检查一些更复杂的机械试验故障的故障模式。

Establishing the effects of long-term physical aging

In conjunction with the physical and mechanical tests, it is also essential to fully understand the effects of long-term physical aging of the composite parts when in service. Over time the material could be exposed to a variety of environmental factors, such as continuous hot/wet conditions, which could plasticize the material and cause a decrease in the composite strength and fiber/matrix interface. Element can help accelerate this aging process in a controlled environment, and the resultant testing of the post-conditioned samples can be used to show the ‘worst case’ test results.

当该测试与原始的室温测试样品以及在亚环境温度下测试的一系列样品的测试相结合时，就可以全面了解材料在所有条件下的性能，确保制造商拥有签署零件以供使用所需的一切。元素还可以帮助制造商了解暴露于其他调节环境（包括清洗液、液压液和燃料）的材料影响。

Taking a complete lifecycle approach to composite testing

Element为复合材料测试提供了一种全生命周期的方法，从项目开始到复合材料制造过程的早期设计和研发（R&D）阶段，一直到保持质量和一致性、故障分析和最终完成提供指导。这包括导航和解释各种测试标准的微妙复杂性所需的关键支持。

Working out of our ISO 17025 accredited state-of-the-art composite testing laboratories, Element provides the full range of mechanical and physical testing needed to prove that a part is fit for purpose. This includes capabilities to physically age specimens to compare ‘best case’ and ‘worst case’ test results and non-destructive testing (NDT) to gather information on any manufactured or accidental defects.

Our team’s wealth of experience working on R&D projects, first part qualification (FPQ) projects, raw material qualifications, and bespoke test projects ensure Element can provide expert advice on the most suitable way to perform a proposed test schedule and ensure accurate, reliable results.

Taking expert advice in the early stage of the test campaign’s definition can be hugely beneficial, saving time and money. Our composite experts work closely with the manufacturer in preparing to test, helping to clarify issues such as which test standard could best prove the properties of interest to whether all the necessary test types have been sufficiently covered in order to prove the part.

确保样品制备过程的顺利进行

样品制备过程的一部分,元素helps to ensure that the proposed test samples being used are of the most suitable geometry and are being taken from the most appropriate locations and directions as well as being sampled at the best frequency. Our team will also help establish the best way to machine and prepare these samples prior to the test. Element’s access to an accredited machine shop enables the extraction, machining, and preparation of test samples in line with the requirements of the relevant test standards, including the ability to apply end tabs and strain gauges if required. We also manufacture and repair composite test panels in line with the customer’s instructions.

For more information on composite qualification testing,please contact us.