No description available.

Free form surface measurement and its subsequent analysis is becoming a subject of considerable interest, not only within the engineering field, but also in bioengineering, medical and dental research. In particular, within the field of dental research, the oral structures comprise a variety of complex free form surfaces, which are often recorded by elastomeric impression materials. In this study, an optical triangulation-based, noncontact probe fitted onto a Co-ordinate Measuring Machine was used to acquire three-dimensional co-ordinate data from such complex free form surfaces. When using an optical probe to digitise a complex free form surface represented by impressions, an optimal digitisation strategy is critical to limit the uncertainty of the data acquisition procedure, because the raw data are the basis for later surface measurement and analysis. This study attempted to optimise a method for three dimensional free form surface data acquisition, measurement and analysis. A theoretical and systematic analysis of error distribution was carried out using standard objects and optimal digitisation strategies were proposed in relation to specified models. Two simulation models of two typical human tooth surfaces were extensively analysed and evaluated. Three reference systems were developed for comparative measurements of those surfaces that have fewer geometrical features. An integrated automatic data acquisition procedure was also developed to scan a large number of impressions. Several successful research applications have been carried out using the methodology developed in this study.

New optical designs strive to achieve extreme performance, and continually increase the complexity of prescribed optical shapes, which often require wide dynamic range and high resolution. SCOTS, or the Software Configurable Optical Test System, can measure a wide range of optical surfaces with high sensitivity using surface slope. This dissertation introduces a high resolution version of SCOTS called SPOTS, or the Slope measuring Portable Optical Test System. SPOTS improves the metrology of surface features on the order of sub-millimeter to decimeter spatial scales and nanometer to micrometer level height scales. Currently there is no optical surface metrology instrument with the same utility. SCOTS uses a computer controlled display (such as an LCD monitor) and camera to measure surface slopes over the entire surface of a mirror. SPOTS differs in that an additional lens is placed near the surface under test. A small prototype system is discussed in general, providing the support for the design of future SPOTS devices. Then the SCOTS instrument transfer function is addressed, which defines the way the system filters surface heights. Lastly, the calibration and performance of larger SPOTS device is analyzed with example measurements of the 8.4-m diameter aspheric Large Synoptic Survey Telescope's (LSST) primary mirror. In general optical systems have a transfer function, which filters data. In the case of optical imaging systems the instrument transfer function (ITF) follows the modulation transfer function (MTF), which causes a reduction of contrast as a function of increasing spatial frequency due to diffraction. In SCOTS, ITF is shown to decrease the measured height of surface features as their spatial frequency increases, and thus the SCOTS and SPOTS ITF is proportional to their camera system's MTF. Theory and simulations are supported by a SCOTS measurement of a test piece with a set of lithographically written sinusoidal surface topographies. In addition, an example of a simple inverse filtering technique is provided. The success of a small SPOTS proof of concept instrument paved the way for a new larger prototype system, which is intended to measure subaperture regions on large optical mirrors. On large optics, the prototype SPOTS is light weight and it rests on the surface being tested. One advantage of this SPOTS is stability over time in maintaining its calibration. Thus the optician can simply place SPOTS on the mirror, perform a simple alignment, collect measurement data, then pick the system up and repeat at a new location. The entire process takes approximately 5 to 10 minutes, of which 3 minutes is spent collecting data. SPOTS' simplicity of design, light weight, robustness, wide dynamic range, and high sensitivity make it a useful tool for optical shop use during the fabrication and testing process of large and small optics.

Aspherical optics are increasingly used these days. The application of aspherical surfaces on large, astronomical telescope mirrors brings challenge to the fabrication. Since the surface radius of curvature varies across the surface, the grinding/polishing tool needs to change its shape when working on different parts of the surface, making surface error more easily embedded into the surface. Therefore, a tighter test-fab loop is needed to guide the fabrication process. To maximize the accuracy during the grinding of the surface and to minimize the working time in the polishing stage, a better metrology device that can measure rough surface is needed to guide the grinding process. Scanning long-wave optical test system (SLOTS) is designed to meet this demand by providing accurate, fast, large dynamic range, and high spatial resolution measurements on rough optical surfaces (surface rms roughness<1.7 µm).SLOTS is a slope measuring deflectometry system that works like a reversed wire test. It measures the reflection of the infrared light off the test surface, and calculates the local slope of the test surface. The surface sag/height is obtained through integration. During the test, a heated metal ribbon radiates long-wave infrared light that is reflected by the test surface. A thermal imaging camera records the reflected light. The ribbon is scanned in two orthogonal directions. From the variation of the irradiance recorded by the camera, slope maps of the test surface can be retrieved in the two orthogonal directions. SLOTS is a combination of tradition slope measurement and modern technology, processing advantages from both parts. It measures surface slope, so there is no need for null optics. It uses an uncooled thermal imaging camera that is made with high resolution and high sensitivity. The linear stage used to scan the hot ribbon has long travel, small resolution, and high accuracy. Both the camera and stage enable SLOTS a large dynamic range and high sensitivity. SLOTS has successfully guided the grinding process of the primary mirror of Daniel K. Inouye Solar Telescope. This mirror is a 4-meter diameter off-axis parabola (OAP). Its largest aspherical departure is 8 mm. SLOTS is able to measure it without any null optics. Under the guidance of SLOTS, the surface shape was controlled to be 1 µm rms within designed shape (with astigmatism removed) at 0.7 µm rms surface roughness (12 µm loose abrasive grits).

No description available.

Self-compacting concrete has soon been around for a decade. Recently the prefabrication industry has started to use this fairly new concrete type in larger scales, mainly because of its distinctive properties.  There are still certain areas that need to be thoroughly examined, such as bond capacity. There have been very few studies regarding shear capacity due to the fact that the procedure is complicated. This report will highlight a method to examine the shear capacity of different surfaces that have been prewetted as well as non-prewetted surfaces. The surface areas follow BBK 04’s and Eurocode 2’s demand for surface roughness.  A smooth surface will be completed in order to confirm if the different shapes influence the bond strength by shear stress or not.                        The purpose of this essay is to measure the bond strength within the shear capacity as well as examine the impact it has on surface roughness and treatment for shear bond. The method used to identify the shear capacity is called L-shaped Push-Off Test. The dimension of the object was selected with the help of a previous research paper. The Sand-Patch method is predominantly used to measure the surface roughness.  The results showed no difference between the demands of surfaces of BBK04 and Eurocode 2 considering the shear capacity. However the non-prewetted surface was measured with the highest shear capacity value. Apart from the shear strength, deformation was measured in both vertical and horizontal direction and it was clearly shown that the vertical deformation was measured to be ten times higher than the horizontal deformation.  There was no difference between the BBK 04 and Eurocode 2 considering the vertical deformation. However the difference occurred on the horizontal direction between BBK 04 and Eurocode 2 where the specimens of Eurocode 2 received three times higher deformation compared to BBK 04. The conclusion can be drawn that the surface roughness of BBK 04 would be more suitable than eurocode2 considering deformation.      The overall result was that the surface treatment with the demands of BBK 04 and Eurocode 2 showed minor difference after being measured with the Push-Off Test method. This has been confirmed with the estimated shear capacity (1.2 MPa). The results revealed that the treatment of surface could be made in either way, brush or rake. As a conclusion the assessment of the shear strength showed that Eurocode 2's demand is too strict comparing demands of BBK 04. / Att bestämma vidhäftningen mellan prefabricerade element och senare pågjutning på arbetsplats är viktigt. Självkompakterande betong är en betongtyp som flera prefabricerade företag börjat använda på grund av dess goda egenskaper. Dock finns några oklarheter som behöver utredas vidare, exempelvis vidhäftningskapaciteten vid pågjutning. I och med införandet av Eurokod blev det större krav på skrovligheten jämfört med tidigare krav i BBK 04. För självkompakterande betong kan det vara svårt att få till en skrovlighet enligt både BBK och speciellt Eurokod. För undersökning av vidhäftningskapacitet kopplat till draghållfastheten finns beprövade metoder som följer svensk standard. Dock finns ingen svensk standard för vidhäftningsprov för skjuvhållfastheten, bland annat på grund av att för få undersökningar har utförts och att provnings-utförandet är mer komplext. Syftet med denna undersökning är att jämföra olika mätmetoder för att mäta skjuvspänningar för vidhäftningen mellan prefabelement och pågjutningsbetong samt att också undersöka olika metoder för att mäta ytjämnheten. Målet är att identifiera skjuvkapaciteten i vidhäftningen samt få reda på vilken påverkan ytjämnhet och ytbehandling har för vidhäftningen. Detta för att utvärdera om Eurokod 2:s hårdare krav på skrovlig yta är nödvändig jämfört med BBK 04 med avseende på skjuvning. Ytor som ska jämföras är avdragen yta och yta som uppfyller BBK 04:s samt Eurokod 2:s  krav på skrovlig yta. Mätmetoder för skrovlighet ska undersökas för att senare utvärderas och användas i undersökningen.  Förutom dessa ytor som normalt förvattnas ska även en yta som följer BBK 04:s krav på skrovlig yta utan förvattning undersökas om förvattning har någon positiv inverkan på vidhäftningen. Den mätmetod som valdes för att identifiera skjuvhållfastheten var L-formad Push-Off-metod, vilket dimensionerades med hjälp av en referensundersökning. Provkroppen tillverkades i Strängbetongs fabrik i Kungsör och innan pågjutningen utfördes mättes ytjämnheten på vidhäftningsytan med hjälp av Sand-Patch-metoden. För att bekräfta validiteten hos Sand-Patch-metoden användes också en annan mätmetod, så kallad Profilmall. Efter att ytorna var uppmätta och pågjutningen hårdnat skickades provkropparna till CBI Betonginstitut för skjuvhållfasthetsprovning samt tryckprovning. Resultaten från undersökningen visade att inga större skillnader i skjuvhållfasthet mättes mellan Eurokods och BBKs krav på ytjämnhet, men det visade sig att den obehandlade ytan klarade av högst skjuvhållfasthet. Alla värden var betydligt högre än vad både Eurokod och BBK 04 anger för hållfasthetsklassen C45/55. Under provningstillfället upptäcktes sprickbildning vid 85 kN både i den befintliga betongen samt vid pågjutningen på de tunnaste delarna, för samtliga provförsök. Utöver skjuvhållfastheten mättes även deformationer såväl vertikalt som horisontellt och det framgick tydligt i resultatet att vertikala deformationerna var mer än tio gånger större än de horisontella. Ingen skillnad mellan BBK och Eurokod kunde tydas vid vertikala deformationer, dock vid horisontella deformationer mättes Eurokod till tre gånger större horisontella deformationer jämfört med BBK. Detta tyder på att BBKs krav på skrovlighet är bättre än Eurokod ur deformationssynvinkel Med denna undersökning som grund kan tillverkarna välja att avstå från Eurokod 2:s hårdare krav på skrovlig yta och fortsätta att behandla ytan enligt BBK 04. I och med detta menar författarna att Eurokod 2:s hårdare krav på skrovlig yta inte är nödvändig jämfört med BBK 04 med avseende på skjuvning (vidhäftning), vilket var det primära målet för undersökningen.

In Electrochemical Machining (ECM), where the material removal takes place based on the anodic dissolution of the workpiece material, the working distance is one of the most important parameters. Especially in Jet Electrochemical Machining (Jet-ECM), where a micro nozzle is moved over the initial surface of the workpiece in order to apply an electrolytic free jet to produce the desired shapes, the distance between the nozzle and the workpiece becomes even more important. On the one hand a small working distance is aspired to achieve high current densities resulting in a high efficiency of the process. On the other hand the working distance needs to be large enough to avoid damages on the micro nozzle caused by electrical discharges or mechanical contact. Hence, the adjustment of the working gap is essential to realize a precise, effective and secure Jet-ECM process. The control of the gap size is done based on the data gathered before machining by surface measurement. Until now, the initial surface has been detected by electrostatic probing through moving the nozzle stepwise to the work piece surface and detect the voltage drop between the nozzle and the work piece. With this strategy, only a limited number of points can be detected within adequate time. Hence, in most cases only three points of the initial surface are detected in order to adjust the working distance according to the planar inclination of the workpiece. The coordinates of the three detected points are used to calculate the normal vector of the initial surface. In recent studies, another strategy was analysed, which is realized by dividing the surface into smaller areas and respectively calculating the normal vector of each area in order to obtain more accurate data of the initial surface. A further strategy is to use probing along the machining path of the tool and to gather the coordinates of a number of points along the path. The above mentioned methods usually do not ensure the precise control of the gap size especially for the surfaces with complex geometry with locally confined convex and concave shapes and are highly affected by the size of the probe. In this study, the application of a laser scanner is investigated for the measurement of the workpiece surface before machining to gather the required data for the adjustment of the working distance during Jet-EC machining of complicated surfaces.

Content: Finished leather is a material purchased by surface measurement. Compared to other goods, which value is defined by a measure, for leather there is no certified reference material able to represent the numerous types of articles present on the market. Moreover, there is not a single type of machine, with the consequent difficulties in comparison of data obtained by different devices on different kind of leather. As far as the devices available are concerned, the pin-wheels machine was the most used device until the sixties, period after which the increasingly massive diffusion of electronic machines began. With regard to the tolerance allowed, in late nineties an agreement between the ICT and ICHSLTA was reached (International Contract N. 7): 2% and 3% for soft and elastic leathers. These limits were fixed without considering the possible deviation of results using different devices and without considering the reproducibility of measures in function of the effective flexibility and physical characteristics of leathers. Over the years, however, the pin-wheel machines have been completely substituted and, due to the high costs of maintenance and management of the pin-wheel machines, only a few of the institutes recognized by ICT, including the SSIP, are equipped with a fully functional pin-wheel machine. Despite this evidence, the Contract continues to consider pin-wheel machine as the reference one for disputes. For the above, an extensive data collection campaign has been carried out involving all the industrial chain of leather: tanneries, brands, users, laboratories, research institutes and devices manufacturers. 16 different kind of leather articles, representative different leather uses (gloves, apparel, footwear, leather goods, furniture, automotive), were measured using all the machines currently available on the market (roller, conveyor, scanner and digital image acquisition devices) and considering ISO 19076 and ISO 11646 measurement procedures as the reference ones. Thousands of data are now available to qualify the behaviour of the leather for each type of machine with its specific characteristics. This was done by statistical robust analysis of the data and by the comparison of the values obtained with the pin machine. The leather used were also mechanically characterized in order to be able to identify any correlations with the reproducibility of the measurements and with the imposed tolerances. Take-Away: The purpose is the possibility to overcome all the restrictions connected with the pin-wheel machine, the improvement of actual EN ISO methods of leather measurement and a better instrument to define tolerances considering the couple leather-machine.

In Electrochemical Machining (ECM), where the material removal takes place based on the anodic dissolution of the workpiece material, the working distance is one of the most important parameters. Especially in Jet Electrochemical Machining (Jet-ECM), where a micro nozzle is moved over the initial surface of the workpiece in order to apply an electrolytic free jet to produce the desired shapes, the distance between the nozzle and the workpiece becomes even more important. On the one hand a small working distance is aspired to achieve high current densities resulting in a high efficiency of the process. On the other hand the working distance needs to be large enough to avoid damages on the micro nozzle caused by electrical discharges or mechanical contact. Hence, the adjustment of the working gap is essential to realize a precise, effective and secure Jet-ECM process. The control of the gap size is done based on the data gathered before machining by surface measurement. Until now, the initial surface has been detected by electrostatic probing through moving the nozzle stepwise to the work piece surface and detect the voltage drop between the nozzle and the work piece. With this strategy, only a limited number of points can be detected within adequate time. Hence, in most cases only three points of the initial surface are detected in order to adjust the working distance according to the planar inclination of the workpiece. The coordinates of the three detected points are used to calculate the normal vector of the initial surface. In recent studies, another strategy was analysed, which is realized by dividing the surface into smaller areas and respectively calculating the normal vector of each area in order to obtain more accurate data of the initial surface. A further strategy is to use probing along the machining path of the tool and to gather the coordinates of a number of points along the path. The above mentioned methods usually do not ensure the precise control of the gap size especially for the surfaces with complex geometry with locally confined convex and concave shapes and are highly affected by the size of the probe. In this study, the application of a laser scanner is investigated for the measurement of the workpiece surface before machining to gather the required data for the adjustment of the working distance during Jet-EC machining of complicated surfaces.