散斑制备工具 The VIC Speckle Pattern Application Kit

 

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数字图像相关技术(DIC)的测量依赖于制备在试件表面的随机的高对比度散斑,以获取最准确的测量结果。 在实践中,如果散斑太稀疏、太密集、或者散斑点过大,都将使测量的空间分辨率受损。 相反,如果斑点太小、混叠,则可能会导致数据嘈杂。 为了减少测量噪音和降低不确定度,需要制备符合视场(FOV)尺度和相机分辨率的理想散斑图案。 VIC散斑制备套件的作用即是帮助用户能够轻松将理想散斑制备于试件表面,而无需对试件区域有精确的了解。 该套件易用、灵活,适用于各种VIC-2DVIC-3D系统的应用场景。 该套件实际上消除了由于试件制备不当而导致的潜在测量偏差。

Digital Image Correlation (DIC) relies on a high-contrast random pattern applied to the specimen’s surface to produce the most accurate results. In practice, if the pattern is too sparse, too dense, or the speckles are too large, spatial resolution of the measurement will suffer. Conversely, if the speckles are too small, aliasing may result causing noisy data. To reduce noise and lower uncertainty, the ideal speckle pattern for the desired field of view (FOV) and camera resolution must be applied.  The VIC Speckle Pattern Application Kit enables the user to easily apply the ideal pattern to the surface of the specimen without any precise knowledge of sample area.  The kit is easy-to-use, flexible, and available for a wide range of applications suitable with your VIC-2D or VIC-3D system.  The kit virtually eliminates the potential bias that would result from poor sample preparation.

CSI公司提供的散斑制备套件包含一系列工具,以供新老DIC用户使用,来快速创建理想的散斑图案。 针对不同视场和图像采集器分辨率组合,还提供散斑点尺寸建议表。 以下列出了套件中所包含的物品。

The speckle application kit from Correlated Solutions provides an array of tools which can be used by new and experienced DIC users alike to quickly create the ideal speckle pattern. Speckle size suggestion tables for multiple fields-of-view and sensor resolution combinations are also provided. The items included in the kit are shown and listed below.

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  • 四个带自动上墨器的压印辊
  • 四个可互换的胶质转印片与一个压克力手柄
  • 三个丝网印刷铜网并配有一个模板框架
  • 一个墨水垫盒与一瓶额外补充装的墨水
  • 硬件可根据用户需求定制创建更大的散斑点
  • Four stamp rollers with self-inking inserts
  • Four interchangeable stamps with one acrylic rocker
  • Three perforated stencils with one stencil frame
  • One ink pad with an extra bottle of ink
  • Hardware to create larger dots available upon request
 

虽然市面已有很多散斑图案制备技术,但是其中很多提供的都是不一致或不规范的散斑点尺寸,这将导致不一致的结果。 当执行重复测试时,这可能尤其令人失望。而使用CSI公司的VIC散斑制备套件生成的散斑点尺寸是可重复一致的,从而能够快速创建精度可以预测和控制的散斑图案,从而实现最高水平的一致且准确的结果

There is a wide range of speckle pattern application techniques, but many provide inconsistent dot sizes from sample to sample, which also yield inconsistent results. This can be especially frustrating when recurring tests are performed. Producing repeatable dot sizes with the VIC Speckle Pattern Application Kit from Correlated Solutions provides the ability to quickly create predictable and controlled speckle patterns, which allows for the highest level of accurate and consistent results.

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为什么散斑图案质量对我们的测量很重要 Why Is Your Speckle Pattern Important?

理想的散斑图案是高对比度的、散斑点分布是随机的、散斑点尺寸大小是一致的、且试件表面上的黑白分布密度是等量的。 如果满足所有这些条件,则我们的测量关注区可将噪音控制在很低的水平,并且能够以非常高的误差确定度进行跟踪测量。

The ideal speckle pattern is high contrast, contains random speckles, consistent dot sizes, and equal amounts of black and white on the sample’s surface. If all of these conditions are met, the area of interest will produce low levels of noise and may be tracked with very high levels of certainty.

以下是各种散斑图案如何影响测量噪声的例子。 中间区域的图案是使用VIC散斑制备套件中的滚筒创建的,而另外两外侧区域上的图案均使用喷漆创建。 正如您所看到的那样,来自散斑制备套件的滚筒产生了高对比度图案,黑色和白色覆盖率约为50%,而喷漆创建的图案只具有较低的对比度以及尺寸不一致的散斑点。

Below is an example of how various speckle patterns can effect measurement noise.  The middle pattern was created using a roller from the VIC Speckle Pattern Application Kit, while the patterns on either side were created using spray paint.  As you can see, the roller from the speckle pattern kit produces a high contrast pattern with approximately 50% black and white coverage, while the painted pattern produces a lower contrast pattern with inconsistent dot sizes.

fig1

图示1: 具有三种不同散斑图案的平板的Z值置信度分析

Figure 1:A relatively flat plate with three different speckle patterns analyzed to show the variable Sigma_Z

图1显示了变量Sigma_Z的二维数据叠加,它是在Z方向上进行测量(离面形状测量)的可置信度。 Sigma值越接近零,所显示的数值就越可能是正确的值。左侧区域图案的对比度低,而且过度细腻,导致Sigma_Z值较大,表明置信度较低。 中间区域显示了较低的Sigma_Z值,这表明对测量具有高置信度。 图中其结果显而易见。

Figure 1 shows a 2D data overlay of the variable Sigma_Z, which is the confidence margin of the measurements taken in the Z direction (out-of-plane shape measurement).  The closer Sigma is to zero, the more statistically likely the value shown is indeed the correct value.  The outside patterns are low in contrast and overly fine which result in larger Sigma_Z values, which indicates less confidence.  The middle pattern shows lower Sigma_Z values, which indicates high confidence in the measurement.  The results speak for themselves.

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图示2: Sigma_Z的3D图显示了差的散斑导致产生了低置信区间和嘈杂的形状测量结果

Figure 2:The 3D plot of Sigma_Z displays how poor patterns create low confidence margins and noisy shape measurements.

为什么置信度Sigma值很重要 Why Is Sigma Important?

VIC-2D和VIC-3D中的高Sigma值表明较高的测量不确定度,这可能导致形状,位移和应变数据中的测量噪声增加。 如图2所示,两侧区域显示比平整的样本的Z值范围较大,而中心区域显示的偏差较小。

High Sigma values in VIC-2D and VIC-3D indicate higher measurement uncertainty, which can result in an increase in measurement noise in the shape, displacement, and strain data.  As Figure 2 shows, the outside patterns show a larger range of Z values of a relatively flat sample, while the center pattern shows much smaller bias.

在下面的图示3中,显示了在刚体转动后变量exx的数据(在X方向上的横向应变),其结果应该是0应变。 而应变云图中显示的应变值范围在两侧外部区域的结果比中心区域高得多,表明两侧局部区域的测量产生了不该存在的应变噪音结果,这会导致不准确的数据。 这可以很好地说明差的散斑图案如何导致噪声影响测量,而好的散斑图案(应用散斑套件)则会产生更好的结果。

In Figure 3 below data for the variable exx (transverse strain in the X direction) is shown for the same plate after a rigid body translation, where there should be zero strain.  The range of strain values shown in the contour plot are much higher on the outside patterns than the center pattern.  The result shows that the local strain measurements on the outside patterns are more noisy and will produce data that is less accurate.  This is a good illustration of how poor speckle patterns can result in noisy measurements, while favorable patterns (applied with the speckle kit) will produce much better results.

通过使用VIC散斑制备套件可帮助用户获得最佳散斑图案,使您的结果噪声更少,数据更准确。

By applying the optimal speckle pattern using the VIC Speckle Pattern Application Kit your results will be less noisy and more accurate.

fig3

图示3:在刚体偏转后显示的横向应变信息。 由于外侧的散斑质量不佳,板的外侧显示出比板中部高得多的噪声。

Figure 3: Transverse strain is shown after a rigid body translation. The outsides of the plate display a much higher level of noise than the middle of the plate due to the poor speckle patterns.

 

 

 

VIC散斑制备套件将提升您的测量结果 The VIC Speckle Pattern Application Kit Will Improve Your Results:

Correlated Solutions,Inc.公司的VIC散斑制备套件可以帮助测量结果保持非常低的噪声和非常高的DIC测量结果的置信度。 散斑制备套件给予新用户和有经验的DIC用户同等的能力,可以为几乎任何镜头和图像采集器组合的不同尺寸视场创建理想的、可重复的散斑图案。 拥有此功能可以简化试件制备过程,确保重复测试结果的一致性,并配合VIC-2D或VIC-3D系统为所有测量获得始终如一的低应变噪声结果

The VIC Speckle Pattern Application Kit from Correlated Solutions, Inc. can help produce very low noise and very high confidence results for DIC measurements.  The speckle kit allows both new and experienced DIC users to create ideal and repeatable patterns for many fields of view for nearly any lens and sensor size combination.  Having this capability can streamline the sample preparation process, ensure consistent patterns for recurring tests, and provide a means to obtain a consistently low strain noise floor for all measurements acquired with your VIC-2D or VIC-3D system.