960 resultados para Materials Testing


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Experimental research on a 150 kW arc-heated plasma testing facility was conducted. Stable plasma jets with different gas compositions, temperatures and velocities were obtained at chamber pressure between 400 Pa – 100 kPa. Stagnation ablation experiments were conducted on samples of typical super alloys used for thermal protection systems. The microstructure and hardness of alloys before and after ablation were compared.

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The motivatitni for" the present work is from .a project sanctioned by TSRO. The work involved the development of a quick and reliable test procedure using microwaves, for tflue inspection of cured propellant samples and a method to monitor the curing conditions of propellant mix undergoing the curing process.Normal testing CHE the propellant samples involvecuttimg a piece from each carton and testing it for their tensile strength. The values are then compared with standard ones and based on this result the sample isaccepted or rejected. The tensile strength is a measure ofdegree of cure of the propellant mix. But this measurementis a destructive procedure as it involves cutting of the sample. Moreover, it does not guarantee against nonuniform curing due to power failure, hot air-line failure,operator error etc. This necessitated the need for the development of a quick and reliable non-destructive test procedure.

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Glycopolymer hydrogels capable of mimicking mucosal tissue in mucoadhesion testing have been designed. Liquid formulations containing mucoadhesive polymers were found to be retained on these tissues to the same extent as ex vivo gastric mucosa, when using a dynamic method of assessing mucoadhesion.

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Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

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In the framework of an international collaboration with South Africa CSIR, the structural design, manufacturing and testing of the new wing for the Modular UAS in composite materials has been performed.

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In areas of seasonal frost, frost susceptibility composed by frost heaving during the winter and thaw softening during the spring is one of the most dangerous phenomenon for transportation, road and railway infrastructure. Therefore, the need for frost protection layer becomes imperative. The purpose of frost protection layer is to prevent frost from penetrating down through the pavement and into the sub-soils. Frost susceptible soils under the road can be cause damages on the roads or other structures due to frost heave or reduced capacity characteristics thaw period. "Frost heave" is the term given to the upwards displacement of the ground surface caused by the formation of ice within soils or aggregates (Rempel et al., 2004). Nowadays in Scandinavia the most common material used in frost protection layer in the pavement structure of roads and in the ballast of the railway tracks are coarse-grain crushed rocks aggregates. Based on the capillary rise, the mechanics of frost heave phenomenon is based on the interaction between aggregates and water, as suggested by Konrad and Lemieux in 2005 that said that the fraction of material below the 0.063 mm sieve for coarse-grained soils must be controlled so as to reduce the sensitivity to frost heave. The study conducted in this thesis project is divided in two parts: - the analysis of the coarse grained aggregates used in frost protection layer in Norway; - the analysis of the frost heave phenomenon in the laboratory under known boundary conditions, through the use of the most widely used method, the frost heave test, in” closed system” (without access of water).

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The first part of this three-part review on the relevance of laboratory testing of composites and adhesives deals with approval requirements for composite materials. We compare the in vivo and in vitro literature data and discuss the relevance of in vitro analyses. The standardized ISO protocols are presented, with a focus on the evaluation of physical parameters. These tests all have a standardized protocol that describes the entire test set-up. The tests analyse flexural strength, depth of cure, susceptibility to ambient light, color stability, water sorption and solubility, and radiopacity. Some tests have a clinical correlation. A high flexural strength, for instance, decreases the risk of fractures of the marginal ridge in posterior restorations and incisal edge build-ups of restored anterior teeth. Other tests do not have a clinical correlation or the threshold values are too low, which results in an approval of materials that show inferior clinical properties (e.g., radiopacity). It is advantageous to know the test set-ups and the ideal threshold values to correctly interpret the material data. Overall, however, laboratory assessment alone cannot ensure the clinical success of a product.

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Based on two research projects, a device for testing the response to-impact of fruits and related materials has been designed and tested during the last three years. As it is not related directly to potatoes, this contribution focuses mainly on the principles of impact and static loading and on the description of the device, and the type of results obtained up to now in different fruits.

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Padding materials are commonly used in fruit packing lines with the objective of diminishing impact damage in postharvest handling. Two sensors, instrumented sphere IS 100 and impact tester, have been compared to analyze the performance of six different padding materials used in Spanish fruit packing lines. Padding materials tested have been classified according to their capability to decrease impact intensities inflicted to fruit in packing lines. A procedure to test padding materials has been developed for "Golden" apples. Its basis is a logistic regression to predict bruise probability in fruit. The model combines two kinds of parameters: padding material parameters measured with IS, and fruit properties.

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Mode of access: Internet.

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Mode of access: Internet.

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Mode of access: Internet.