当用于材料测试时，延伸仪将用欧洲杯足球竞彩于准确测量对广泛工程设计至关重要的材料特性 - 飞机，能源系统，医疗设备和民用结构，仅举几例。通常，人类的生活取决于用延伸计进行的准确和一致的测量。
用于金属拉伸测试的延伸计
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Testing structural materials often requires extensometers to make accurate extension measurements of only a few microns or tens of microns (which are much too small to see without magnification), and sometimes while under dynamic conditions at 1200 °C, or submerged in corrosive liquids. Measuring the properties of extremely extensible materials such as latex rubber is also typical.
当在测试机中施加力时，伸展计测量材料样品的延伸，压缩或剪切变形。使用延伸计时，可以测量诸如弹性模量，偏移量和完全应力 - 应变曲线等临界特性。它们通常用于测量测试件的菌株，这是通过将测试样品长度的变化除以其原始量规长度来计算的。
This article’s discussion also applies to transverse/diametral extensometers used to measure Poisson’s ratio and r-values of sheet metal, crack opening displacement gages (COD gages) used for fatigue crack growth testing and fracture mechanics, and for deflectometers used to measure displacement in flexural testing. The term “extensometer” will be used to encompass all of these transducer types throughout this article.
鳕鱼量用于浸入盐水时的断裂韧性测试（上面显示的CAD模型）
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直接在测试样品上测量应变（或位移）。结果，与基于测试机的握把的运动相比，它们提供了更准确和可重复的测量值，其中包括测试机的合规性错误。它们具有多种形状，尺寸，测量能力和温度等级，并且可以直接与样品接触或在不接触样品的情况下进行光学测量。延伸计可重复使用，并且持续了多年，并且与粘合键合的应变量表或数字成像测量相比，它们非常具有成本效益。延伸计通常是为特定应用而设计的，例如在涡轮发动机中使用的合金的疲劳寿命，航空航天粘合剂的剪切模量或混凝土的压缩特性。
专业类型的延伸计用于岩土测量和钻孔钻孔，但本文着重于为材料测试设计的延伸仪。欧洲杯足球竞彩
校准，验证和可追溯性的重要性
With so much depending on measurements made using extensometers, how can you make sure that the measurements are accurate and comparable between different test labs? The answer: calibration and traceable verification.
校准
校准is the process of adjusting the testing machine’s electronics to make the extensometer and electronics’ output, as a pair, match a reference. The reference can be based on moving the extensometer to a known displacement using an extensometer calibrator or electrically changing the extensometer’s output using an electrical reference such as a分流校准。
通常，仅校准通常不能确保在测试开始后不久的临界应变测量是正确的。这是验证和可追溯性进来的地方。
延伸计Calibratorwith Extensometer Attached
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确认
一旦将延期计和材料测试机校准为系统，将延期计，电子和读数（或欧洲杯足球竞彩数据采集软件）作为系统也至关重要。
通过验证，目标是证明与参考相比，使用特定的延伸计，电子和读数（延长计测量系统）进行的测量是准确的。该参考通常是一种延长计校准器，已通过可追溯性对国际单位系统（SI）进行了校准。
During verification, the extensometer is attached to the extensometer calibrator, and the calibrator is moved to many positions between the extensometer’s zero and full-scale displacements. At each position, the extensometer measuring system’s output is compared to the calibrator’s output. Since the calibrator is the reference, differences between the extensometer and calibrator readings are errors in the extensometer measuring system. The errors are recorded and compared to allowable accuracy class limits for the errors.ISO 9513和ASTM E83指定过程和准确性类限制。
Without traceability and verification, you cannot be certain whether your measurements are comparable to other labs, such as your customer’s, or even if data from a different testing machine and extensometer in your own lab would agree. Just imagine what would happen if tests in your lab indicate that your product meets specifications, but your customer’s test lab shows that your product does not. Traceable verification will be one of the first things that both companies check.
延长计的量规长度和测量范围是多少？
What is Gauge Length?
延长计的仪表长度是测试样品上延伸计的初始测量点之间的距离。
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如果您使用的是测试标准（例如ISO或ASTM标准），请检查标准计的延长计规长度要求。许多测试标准指定了样品尺寸和匹配的延长计尺度长度。
什么是测量范围？
An extensometer’s Measuring Range is the extensometer’s measuring capacity in tension (+) or compression (-) in units of % strain, maximum extension, or maximum deflection. When the measuring range is specified in units of % strain, this refers to the maximum extension as a percentage of the initial gauge length. Maximum extension, displacement, or deflection will be in length units such as millimeters.
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在确定应用所需的测量范围时，估计您需要测量的最大应变或伸展值，例如骨折时的样品伸长或总应变时，当取消收益率后延期计时。接下来，为满足或超过这些要求的延长计选择一个测量范围。如果您使用的是测试标准，还可以检查标准是否有延长计要求。
伸展计如何与测试机连接？
Most extensometers have either a strain gage bridge or a “high-level” analog output (usually ±10V or 0-10V). Some extensometers use LVDTs, quadrature-output encoders, analog potentiometers, or digital processors that provide measurements as a serial data stream. In any case, the testing machine must have electronics that are suitable for the type of extensometer. For example, electronics for a “strain-gaged extensometer” will need to supply an excitation voltage to the extensometer’s strain gage bridge and will have to amplify its millivolt-level output.
延伸计带有圆金金属张力标本
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测试机构制造商通常会出售此类电子产品，因此，如果最初购买了没有任何扩展计的测试机，则可能必须添加电子产品。有时，对于较旧的测试机，不可能将必要的电子设备添加到测试机控制器中，并且需要外部，独立的电子设备。
如何指定延长计
First, determine what gauge length and measuring range are required for your applications. Often several gauge lengths are required for testing various specimens, and additional kits to adjust the gauge length or additional extensometers are necessary to meet all requirements.
此外，您的标本可能需要几个不同的测量范围，因此需要几个延伸仪。在大多数情况下，在应变或位移值进行关键测量值时，您将获得最佳的数据质量，以大于延期计测量范围的1％。例如，在使用具有100％应变范围的延伸计测量金属样品的0.2％偏移量时，您可能会获得差的数据质量。对于该应用程序，建议您使用速度计，其测量范围为50％或25％。
另外，确定要测试的样品温度范围。是否需要在测试温度处的延伸计位于环境室或低温露水中使用延伸计？
最后，确保测试机的电子设备可以与要使用的延伸计类型一起使用。例如，应变仪的延伸计需要该类型的传感器的电子设备。
Remember to determine how you will calibrate the extensometer and the testing machine in advance, and how you will verify the accuracy of the extensometer measuring system. Planning and budgeting for this final step are crucial.
概括
延伸计对于测量基本材料特性（例如弹性模量，屈服强度和应力应变曲线欧洲杯足球竞彩）的材料测试实验室至关重要。为了获得可以预期与其他测试实验室一致的测量结果，例如供应商的实验室和客户的实验室，可追溯验证至关重要。在Epsilon Technology的知识中心了解有关延伸仪的更多信息。