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The article focuses on the aging and degradation of polymer foil sheets by analyzing weather impacts on light polymer foil used for additional roofing underlays in sloping roofs. The author relies on tests for specific material properties exposed to various weather conditions. Inspecting effects of different types of weather, he concludes that solar radiation is the most impactful factor on the overall state and degree of material degradation. [ABSTRACT FROM AUTHOR]

The ambition of this study is the development of innovative composite structures made of steel-fiber reinforced Ultra-High Performance Concrete (UHPC) and Fiber-Reinforced Polymers (FRP). The new composite construction method is characterized by low self-weight, high durability and simplicity, and could represent a robust alternative to prefabricated steel, timber or normal concrete elements. Within the study, two different types of composite structures are investigated: composite structures consisting of UHPC and structural profiles made of Glassfiber-Reinforced Polymers (GFRP), as well as UHPC structures with reinforcement made of Carbonfiber-Reinforced Polymer (CFRP) lamellae. For evaluation of feasibility, a comprehensive theoretical and experimental research into the bond and bending behavior of UHPC-FRP composites is carried out and several structural building applications like beams, shells and façade elements are investigated. [ABSTRACT FROM AUTHOR]

A test series of PVC windows with different configurations were carried out under laboratory conditions. Thickness of PVC profiles and design of an insulating glass unit were the variable parameters, while the hardware and overall specimen dimensions stay the same. Tests were performed in several stages: only under wind load (according to the standard method); only under temperature load and under the combination of wind and temperature loads (according to a specially developed method). During the tests a sag of window profile elements were measured using linear displacement sensors. The studies have revealed a number of factors and phenomena which are not currently considered in window structures design and strength analysis: a significant influence of PVC profile stiffness on a mullion deflection, the influence of insulating glass unit stiffness on casement window elements deformation, and the influence of hinge joints mobility on casement displacement. It was established, that not only a window mullion, but also a frame should be considered as the element under calculation in the case of wind and temperature loads simultaneous action. The seal failure is observed exactly in the place where the sash adjoins the window frame. These two elements have quite different stiffens, which leads to different deflections and, as consequents, to gaps formation, while the mullion deflection is commensurable with those of the sash and their joint stays airtight. The considered phenomenon must be taken into account when developing the design solution of window hardware (pitch and locations of fixing points). [ABSTRACT FROM AUTHOR]

Certain elements of the mechanisms behind the deflagration-to-detonation transition (DDT) of high explosives (HE) in weak confinement are still poorly understood. At Los Alamos National Laboratory, we have developed a piston-impact-ignited DDT experiment to promptly initiate the one-dimensional compressive burning of a column of weakly confined HE in order to explore and observe how the Type I DDT process in weak confinement varies from what has been well described when strong metal confinement is used. The experiment consists of a smokeless-powder-propellant gun and an HE-sample holder. The smokeless-powder gun is used to accelerate a right-circular-cylindrical projectile to impact and ignite a column of weakly confined HE held in the test-sample holder. The gun itself houses two diagnostics: a custom single/dual-channel optical encoder used to continuously track the position of the projectile during the informative majority of the test, and a piezoelectric pressure sensor used to observe the pressure of the propelling gas in the bore of the gun. Multiple other diagnostics can be successfully fielded on each test including high-speed video, streak imaging, and an in-house four-channel pyrometer. To study the DDT process, we completed a test series of more than 25 successful impact-ignited tests involving confined HE using this new experiment. The majority of the impact velocities observed in this series ranged from ∼120-160 meters per second, usually using a projectile mass of ∼19 grams. Results from the test series showed interesting behavior pertaining to Type 1 DDT of both pressed-pellet and hand-tamped-powder PETN samples. Among the most notable results from the test series was the recording of a Type 1 DDT of a column of PETN powder. The sample was hand-tamped to 75% theoretical maximum density (TMD) in an annealed-polycarbonate-confinement tube and impacted by a 19.8g projectile traveling 154 m/s. Two high-speed video cameras (Phantom v2512 color @ 271,000 images per second (ips), and Phantom v710 monochromatic @ 990,000 ips) captured all stages of the experiment including: impact, generation of compaction wave, initiation of a 1D compressive burn, and the transition from deflagration to detonation. [ABSTRACT FROM AUTHOR]

Due to their favourable spectrum of properties, thermosets are becoming increasingly important in the course of growing electrification and increasing power density in automotive construction. As a result of the cross-linking, thermosets exhibit almost constant mechanical properties over a wide temperature range. The often used high filler content of approx. 80 wt.% also leads to an extremely low shrinkage level, which means that close tolerances can be achieved. Thermosets have a similar coefficient of thermal expansion to steel and no characteristic creep behaviour, so that thermosets are an ideal material for screwing. Up to now, there are no guidelines for the design of screw-in tubes and direct screw connections in thermoset moulding compounds. The design is currently based on the guidelines for thermoplastics, whose material behaviour cannot be completely transferred to thermosets. This leads to the fact that extensive validation test series are necessary in order to guarantee sufficient process reliability. The aim of a public research project is to develop a material-optimised screw-in tube geometry for direct screw connections in thermosets and to gain knowledge about the material and failure behaviour. For this purpose, the influence of characteristic process parameters and of the tube geometry on the fastening reliability is statistically analysed. The quality parameters used for this are the screw connection parameters, installation and stripping torque, as indicators for the screw ability and reproducibility of the screw connection. Furthermore, the time-dependent decrease of the pre-load force is investigated in order to evaluate the screw connection reliability. With a reduced processing temperature, the screwing security can be further optimised and the quality-determining preload relaxation can be further reduced. With regard to the geometry design, the choice of the core hole diameter and the screw-in length has the greatest influence on the screw connection reliability. Increasing the outer diameter can also improve pre-load relief and enable joint repair, thus extending the product life cycle. [ABSTRACT FROM AUTHOR]

Some recycled plastics would provide the mechanical, thermal, and optical properties to replace virgin materials in some applications, but they are not used because of their odor. The reason for the unpleasant odour of post-consumer recyclates is that they are containing volatile compounds from their former applications, which also may have undergone degradation in the recycling steps, like residues from food or drinks which were stored in the package. We found that a reduction of such emissions is possible in the melt processing step of the recycling in a previous work but saw a big influence of processing parameters as the material will also further degrade in this step [1]. Therefore, the aim of this work was to investigate the reduction of the emissions in a co-rotating twin screw extruder with vacuum degassing, with an emphasis on different temperature profiles and screw configurations. Previous tests have shown that the temperature is a major factor to reduce the emissions, but around 250°C degradation effects have a negative influence. Therefore, another test series was processed to validate this effect and to find the optimal temperature settings for the process. The untreated recyclate was processed with different screw configurations. The emissions of all the compounds were determined with gas chromatography according to VDA 277. Further, mechanical characterization with tensile and notched impact tests was carried out to investigate the effects of the different processing parameters on the materials behavior. In addition, also the Oxidation Induction Time was determined to check how much of the stabilizer is left in the material. The results were compared to find the best settings for the process. The first tests with different screws show that emissions can be reduced over 70% with the right screw configuration and process settings. [ABSTRACT FROM AUTHOR]

Currently, there are no series applications of thermoset and rubber manufactured by multicomponent injection molding. For the reasons that the material behavior of thermoset and rubber is suitable for technical applications, mainly for high temperatures and chemical aggressive surrounding, as well as that their curing behavior is very similar in injection molding, the processing of multicomponent injection molding using reactive materials (thermoset and rubber) were analyzed. In present study, factors determining compound properties, the adhesive strength of the compounds, were investigated. The results show the practicality to create thermoset-rubber compounds with multicomponent injection molding technology and reveal important influencing variables for the compound properties and in the special case of the adhesive strength of the compounds. [ABSTRACT FROM AUTHOR]

Reliability demands for products in power electronics have increased as the desired lifetime of high reliability products has been raised from ten to even thirty years. Increased lifetime and reliability demands along with decreasing time to market have also affected the reliability testing needed for such products. To achieve more accurate reliability results in less time, combined stress testing methods have attracted more attention in recent studies. In this paper, accelerated reliability testing using combined stress testing method was conducted on commercial motor drives. The motor drives were tested in high temperature and high humidity test combined with power cycling. Additionally, input power interruption was included in part of the tests. The aim of this research was to study the effect of input power interruptions on failure times and failure modes. The results from the tests show clear differences between tests conducted either with or without input power interruptions. Shorter failure times were achieved when input power interruptions were included in the test procedure. However, they also changed the failure modes between the tests. As a conclusion, the different test methods reported in this study accelerated different failure mechanisms. Consequently, if power interruptions are used in testing, power interruption parameters and the relevance of failure modes occurring in accelerated testing compared to those seen in actual use conditions should be considered carefully. [ABSTRACT FROM PUBLISHER]

Successful development of space fission systems will require an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. Testing can be divided into two categories, non-nuclear tests and nuclear tests. Full power nuclear tests of space fission systems are expensive, time consuming, and of limited use, even in the best of programmatic environments. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. Non-nuclear tests are affordable and timely, and the cause of component and system failures can be quickly and accurately identified. MSFC is leading a Safe Affordable Fission Engine (SAFE) test series whose ultimate goal is the demonstration of a 300 kW flight configuration system using non-nuclear testing. This test series is carried out in collaboration with other NASA centers, other government agencies, industry, and universities. If SAFE-related nuclear tests are desired, they will have a high probability of success and can be performed at existing nuclear facilities. The paper describes the SAFE non-nuclear test series, which includes test article descriptions, test results and conclusions, and future test plans. [ABSTRACT FROM AUTHOR]

Due to their ability to form fusion bonds, composites with thermoplastic matrix offer new opportunities to assemble complex structures with a multitude of single components. By combining the laser-assisted Thermoplastic Automated Fiber Placement process (TP-AFP) with the thermoforming technology, a time-efficient process chain for producing hollow skin-stiffener structures was developed. Removable core systems are inserted into the cavity of thermoformed omega profiles for subsequent TP-AFP processing of skin layers to the top of the flanges. This enables in-situ joining between the flanges of the thermoformed profile and the skin layers without the need for other joining technologies or supplementary bonding materials. Mode I interlaminar fracture toughness tests were conducted to evaluate the performance of this joining strategy. Partially fiber-placed and thermoformed test specimen were produced by the combined TP-AFP/thermoforming process transferring the developed joining strategy to coupon level. In addition, fiber-placed specimens were manufactured with and without additional processing in a press to act as a reference. The effects of different cooling rates during production of the test panels on the crystallinity were determined by Differential Scanning Calorimetry (DSC). The mode I interlaminar fracture toughness test results show that partially fiber-placed and thermoformed test specimen have a comparable level of resistance against delamination as entirely fiber-placed or thermoformed test specimen. The similar amount of crystallinity of these test panels, determined by an introduced crystallinity ratio (CR), correlates with the mode I interlaminar fracture toughness test results and indicates a low influence of the developed joining strategy on the crystallinity amount at the joint zone. [ABSTRACT FROM AUTHOR]

This paper presents the results of a series of exploratory tests of the developed recurrent neural networks (RNN) architecture xMANN (external memory memory-augmented neural network). The performance of RNN architecture xMANN was evaluated by comparing the results of the test series with the results obtained using RNN control architecture LSTM (long short-term memory) Tests were conducted with different initial conditions: composition of input data; option of educational trajectory sampling; size of embedding vector for events; size of 'window' in embedding layer training; number of iterations in embedding layer training; number of batches in RNN training; number of epochs in RNN training; Percentage of training examples; Fraction of trajectories used for cross-validation of RNN training epoch results. The result was a configuration of the raw data and hyperparameters of recurrent neural networks training and features of its architecture such that they enabled the prediction of the optimal learning trajectory with the maximum value of the accuracy function and the minimum value of the loss function. The xMANN architecture showed an advantage over the LSTM architecture in predicting the optimal educational trajectory accuracy for all series of experiments. On average, the loss function value for xMANN is 0.34 lower than LSTM for all series of trials, the 'area under curve' indicator is on average 0.07 higher than LSTM. [ABSTRACT FROM AUTHOR]

Since the out-of-pile semi-integral tests performed at Studsvik in 2011 for the NRC [1] and the Halden Loss-Of-Coolant Accident (LOCA) test series IFA-650 [2], a major safety interest has raised for Fuel Fragmentation, Relocation and Dispersal (FFRD) during a LOCA sequence. In addition to the characteristics of the fuel ejected from the rod after the clad failure, the fuel behaviour before the clad failure is still to be investigated, especially its fragmentation and its possible relocation within the rod during the clad ballooning phase. Furthermore, the chronology and the sequencing of these phenomena is of particular interest. For this purpose, the VINON-LOCA program, lying in the framework of a trilateral agreement between EDF, Framatome and CEA, is aimed at performing Out-Of-Pile heating tests on irradiated repressurized fuel rods, reproducing a typical Loss Of Coolant Accident thermal sequence. The VINON-LOCA experimental set-up is located in the so-called VERDON lab of the LECA-STAR hot cell complex. This lab was dedicated to the VERDON-ISTP program [3]. The VINON-LOCA set-up is thus largely instrumented for addressing not only these FFRD topics, but also Fission Gas Release (FGR), combining both online measurement (gamma stations, gamma camera, acoustic sensor, pressure, temperatures, flow meters, microGC...), and preand post-test characterization (gamma scanning, tomography, metrology, fuel fragments weighing and sieving, gas analyses...). An extensive and substantial qualification campaign has been performed to validate the furnace design regarding the desired test conditions, and to qualify the instrumentation. Following some preliminary modelling and calculations, it has included tests on an out-of-cell twin mockup and tests on dummy inactive rods in the hot cell. This allowed achieving successfully the first experimental qualification test of the program end of 2019 on an irradiated UO2 fuel rodlet. A second irradiated experiment is planned with increased instrumentation capabilities, notably a 2D gamma camera for online fuel motion detection. [ABSTRACT FROM AUTHOR]

Successful development of space fission systems requires an extensive program of affordable and realistic testing. In addition to tests related to design/development of the fission system, realistic testing of the actual flight unit must also be performed. If the system is designed to operate within established radiation damage and fuel burn up limits while simultaneously being designed to allow close simulation of heat from fission using resistance heaters, high confidence in fission system performance and lifetime can be attained through a series of non-nuclear tests. The Safe Affordable Fission Engine (SAFE) test series, whose ultimate goal is the demonstration of a 300 kW flight configuration system, has demonstrated that realistic testing can be performed using non-nuclear methods. This test series, carried out in collaboration with other NASA centers, other government agencies, industry, and universities, successfully completed a testing program with a 30 kWt core, Stirling engine, and ion engine configuration. Additionally, a 100 kWt core is in fabrication and appropriate test facilities are being reconfigured. This paper describes the current SAFE non-nuclear tests, which includes test article descriptions, test results and conclusions, and future test plans. [ABSTRACT FROM AUTHOR]

Keeping the reflector component clean is a big challenge in the solar energy industry. In order to optimize cleaning strategies, a precise and repeatable experimental procedure, which is capable of replicating a sequential soiling process under laboratory condition is required. An artificial soiling method and a test-rig with a glass drop-tube were designed and its performance was tested. The test-rig provides soiled samples, which are up to 16.3 % "under-soiled". Specular reflectivity differences on soiled samples are smaller than 5% reflectance. Sequential soiling tests, with a target MDD∼0.25 g/m2 were repeated up to 10 times. This represents an average daily soiling load globally. The current method can be further optimized. [ABSTRACT FROM AUTHOR]

One of the ways to save raw materials and energy resources is the introduction of non-destructive testing at precast concrete factories as an integral part of comprehensive quality control. This article discusses non-destructive methods for determining the strength of concrete, describes and presents the results and analysis of studies. Two main test methods were identified and compared - drilling and ultrasonic methods. Including used a comprehensive test method. The procedure involved a random selection of cubes for each test series. Each type of test was subjected to 10 cubes. Impact, indentation and ultrasonic tests were carried out in accordance with the existing Code. The drilling method was defined as new. According to the test results, graphs are built. Analysis of the graphs obtained gives a more complete picture of the strength properties of materials and structures. Complex tests allow us to assume the further nature of the behavior of materials and structures under the influence of loads in comparison with the case when only one test method is used. One of the ways to save raw materials and energy resources is the introduction of non-destructive testing at precast concrete factories as an integral part of comprehensive quality control. [ABSTRACT FROM AUTHOR]

The Thinking methods methodology searches to develop, activate and boost human intelligence. The conscientious use of thinking methods allows individuals and teams to better deploy brainwork and "wire" individuals into a collective thinking process, increasing agility and quality of collective sensemaking and collective intelligence. This methodology can be included into innovation methods as well as in strategy development processes. It allows to increase the quality of those methods and processes. First results (research in progress) show that this fosters sustainable and systemic innovation. Also this methodology can be taught in combination with teaching content like innovation or marketing, with the objective that students acquire not only the content but also learn to implement it, using the most efficient thinking methods. To harden the methodology, further test series shall be conducted in a neuroscientific setup. VR should be considered for such a setup. [ABSTRACT FROM AUTHOR]

The paper describes the application concept of additive manufactured dies to support the robot-based incremental sheet metal forming process ('Roboforming') for the production of sheet metal components in small batch sizes. Compared to the dieless kinematic-based generation of a shape by means of two cooperating industrial robots, the supporting robot models a die on the back of the metal sheet by using the robot-based fused layer manufacturing process (FLM). This tool chain is software-defined and preserves the high geometrical form flexibility of Roboforming while flexibly generating support structures adapted to the final part's geometry. Test series serve to confirm the feasibility of the concept by investigating the process challenges of the adhesion to the sheet surface and the general stability as well as the influence on the geometric accuracy compared to the well-known forming strategies. [ABSTRACT FROM AUTHOR]

Timber buildings do not have a high acoustic performance regarding vibration transmission through the structure. To find out the peculiarity of timber sound conduction, an acoustic lab test with CLT was set up. Several measurement configurations were built and airborne sound measurements according to EN ISO 16283-1 and impact sound measurements according to EN ISO 16283-2 were carried out. The test results were set in relation to reference measurements on the bare CLT slab and on a floor assembly, with and without decoupling bearing stripes and with and without connectors. In addition to the standard sound measurements, the sound transmissions through the ceiling element and through the flank components (walls) were also measured with accelerometers. The results showed in an experimental evaluation method a reduction of the apparent sound reduction index R' and normalized impact sound pressure level L'n. All tests were carried out with the same load of 17 kN/m on the decoupling bearing stripes and the ceiling element. The load was applied by means of threaded rods and secured by strain gauges. The influence of decoupling bearings stripes, types of fastening systems and floor structures on sound transmission through the flanking components on a real scale mock-up could therefore be investigated. [ABSTRACT FROM AUTHOR]

Direct tensile test were conducted under various loading rates in order to study the time dependence of tensile strength of concrete. The loading rates applied vary to such an extent that failure of the concrete specimens in tension occurs after time periods ranging from 3-5 seconds to 3-4 days. Concrete in strength classes C28/35 and C53/65 which hardened under various curing conditions were tested. The influence of the loading rate on the tensile strength and the appropriateness of a sustained loading factor are discussed. In this paper, test results for the strength class C28/35 are introduced. [ABSTRACT FROM AUTHOR]

One issue with the use of crosslinked polyethylene (XLPE) insulation in high voltage power cables is the presence of oxidized particles. Oxidation may occur during production of polyethylene, during the extrusion and curing process used to produce XLPE cables, or in subsequent processes/operation of the cables. Oxidized particles are here referred to as organic contaminants. In the present study artificial organic contaminants were introduced in XLPE samples made for electrical treeing measurements. Instead of using the common needle-needle or needle-plane configuration, a wire-plane configuration was used. Organic contaminants have an increasing conductivity and permittivity as function of increasing degree of oxidation. These properties most probably give rise to local electric field enhancements in the material. The morphology of organic contaminants also differs from virgin XLPE, which probably cause bad adhesion between the XLPE matrix and the contaminants. A combination of these factors was found to affect the electrical performance of the insulation. Several different parameters, such as dry and wet ageing, as well as AC voltage and DC voltage stress, were included in the study. [ABSTRACT FROM PUBLISHER]

Cast polyamides, which are synthesized through anionical polymerization in a forming mold, have a high molecular weight compared to polyamides synthesized through polycondensation. However, high amounts of wastes (e.g. unusable sprues, post-processing wastes) occur with this production method. Because of this and due to the high molecular weight of the cast polyamide, compounding of the wastes and a further processing via methods like thermoforming is a potential approach for the recycling of polyamide wastes. However, when the polyamide wastes are recycled in a twinscrew extruder, the remaining catalyst, which is embedded within the wastes, can lead to a degradation of the polyamide chains. This degradation results in molecular weights respectively melt viscosities, which are suitable for processing via injection molding but not suitable for methods like thermoforming, for which high viscosities are necessary. In this work, cast polyamide wastes were compounded in a twin-screw extruder with additives to obtain maximum viscosities. We considered (mono- and di-)carboxylic acids, which act as catalyst catchers, as well as different additives, which increase the molecular weight, (linear chain extenders and multifunctional polymeric backbones). After the compounding, rheological measurements were conducted to examine the degree of the viscosity increase and thermal measurements to estimate a processing window for thermoforming. The rheological measurements showed that the increase is strongly dependent on the waste batches, which were used for the respective test series. However, the thermal properties were not influenced through the polymer modification. Overall, viscosities could be reached, which were high enough to produce semi-finished parts out of the compounds. Additionally, thermoformed polyamide parts with exact forming shape as well as constant wall thicknesses were realized. [ABSTRACT FROM AUTHOR]