Zoltan Major

Squeeze-flow testing is a commonly used experimental method for characterising the flow behaviour of high-performance C-SMCs under typical compression moulding conditions. A European benchmark exercise involving 14 research institutes is currently being conducted to identify the sources of variability in squeeze flow testing results and to support the development of a standardised testing methodology. Experimental testing of five C-SMC materials has been completed using a well-defined testing procedure.This paper focuses on the data processing stage of the benchmark exercise, in which experimental data collected from all participants are processed and analysed to extract information on raw material variability, force–gap height relationships, and flow-front profiles. Qualitative assessment of these results is used to identify the critical sources of variability, which subsequently informs a more detailed statistical analysis.

This study introduces a methodology for characterizing and modeling the viscosity and specific volume–pressure–temperature (pvT) behavior of sheet molding compound (SMC) materials, based on the use of specialized testing equipment. Conventional rheometers are inadequate for such materials due to the presence of long fibers, necessitating the use of specialized equipment like squeeze flow rheometers and pvT dilatometers. Our findings demonstrate that traditional oscillatoric rheometer measurements underestimate the viscosity of CF-SMCs, highlighting the need for advanced, albeit non-standardized, testing methods. Additionally, we found that standard Tait models failed to capture the temperature-dependent porosity of CF-SMCs at low pressures, whereas models based on thermodynamic state variables (TSVs) provided accurate predictions across a broader range of conditions. The study also addressed the complexities introduced by fiber–flow coupling and the fiber orientation in measuring the viscosity, revealing limitations in conventional modeling approaches. The numerical analysis showed that a power law-based anisotropic viscosity model (PL-IISO) combined with a TSV model offered the best predictive performance in finite volume flow simulations, especially for thick-walled regions. However, the current modeling approaches have limited predictive capabilities for the fiber orientation in thin-walled regions. This research underscores the challenges in accurately modeling CF-SMC materials in terms of the fiber orientation, whereas the compression forces needed from the pressing machine could be predicted accurately within an average error of 6.5% in the squeeze flow experiments.

This study investigates the mechanical and dynamic thermomechanical properties of thermoplastic sheet molding compounds (TP‐SMC) combined with thermoplastic polyurethane (TPU) to enhance damping while maintaining structural integrity. The methodology uses SMC, a residual material from UD tape processing, to further enhance sustainability. By combining SMC with TPU, a hybrid material is created that merges the high stiffness of the composite with improved damping capabilities. The research explores the effect of varying TPU content (0%, 20%, 40%, and 60%) on composite properties. Results show that TPU incorporation significantly improves damping properties, with diminishing improvements observed beyond 40% TPU content. The glass transition temperature of the TPU defines the lower application limit of the composites, while lofting behavior, also influenced by the TPU content, defines the upper application limit. These SMC‐TPU composites have potential in automotive and aerospace applications requiring vibration damping and robust performance. Future research should focus on optimizing manufacturing processes and exploring other thermoplastic matrices.

A magyar vasúti hálózat európai törzshálózatba (TEN-T) tartozó elemeinek teljes körű felújítása, modernizációja fokozott ütemben kezdődött meg a 2009-2016 közötti KÖZOP finanszírozási program keretében. A korszerű technológiák bevezetése kézenfekvő megoldás volt a vasúti alépítmény rehabilitációjának elvégzéséhez is tekintve a program során munkáltatás alá vett jelentős vágányhosszakat. A Magyarországon új technológia honosításához azonban a tervezési, műszaki ellenőrzési és kivitelezési folyamatokat szabályozó előírásrendszereket is meg kellett újítani. A kivitelezési munkák megkezdése előtt a vasúti nagygépes alépítményjavítási technológiához nélkülözhetetlen törtszemcsés kiegészítő réteg anyagának hazai körülmények között elérhető kőbányákból származó keverékét is ki kellett kísérletezni. A honosítási folyamat során a tervezési és műszaki ellenőrzési metódusok eleinte párhuzamosan folytak a korábban alkalmazott eljárásokkal míg az egyenértékűség igazolásra került. Laboratóriumi tesztek és próbaszakaszok építésével történt a kőanyag keverékterv és a technológia véglegesítése. Az alkalmazott új építési módszer a magas műszaki színvonal és a konvencionális technológiához képest igen gyors kivitelezési idő miatt jelentős vágányzári idő csökkenést eredményezett és több fontos környezetvédelmi szempontból is előnyös folyamat alkalmazását is lehetővé tette. A gépláncok a teljes zúzottkő recycling technológiával a be és kiszállítandó kőanyagok mennyiségét csökkentették, mint az alépítményi kiegészítőréteg, mint az ágyazati kőanyag tekintetében. A korszerű vasúti nagygépes alépítményjavítási technológia alkalmazásának köszönhetően az elért magas műszaki színvonal mellett az átépítési munkák CO2 kibocsátása és ezzel párhuzamosan a vasútvonalak ökológiai lábnyoma is csökkent.

Background: Hemodynamics during the growth process of cerebral aneurysms are incompletely understood. We developed a novel fluid–structure interaction analysis method for the identification of relevant scenarios of aneurysm onset. Method: This method integrates both fluid dynamics and structural mechanics, as well as their mutual interaction, for a comprehensive analysis. Patients with a single unruptured cerebral aneurysm were included. Results: Overall, three scenarios were identified. In scenario A, wall shear stress (WSS) was low, and the oscillatory shear index (OSI) was high in large areas within the region of aneurysm onset (RAO). In scenario B, the quantities indicated a reversed behavior, where WSS was high and OSI was low. In the last scenario C, a behavior in-between was found, with scenarios A and B coexisting simultaneously in the RAO. Structural mechanics demonstrated a similar but independent trend. Further, we analyzed the change in hemodynamics between the onset and a fully developed aneurysm. While scenarios A and C remained unchanged during aneurysm growth, 47% of aneurysms in scenario B changed into scenario A and 20% into scenario C. Conclusions: In conclusion, these findings suggest that WSS and the OSI are reciprocally regulated, and both low and high WSS/OSI conditions can lead to aneurysm onset.

Asphalt pavements are fundamental to modern transportation infrastructure, requiring elasticity, firmness, and longevity. However, traditional asphalt, based on bitumen, faces several limitations. To improve pavement performance, polymer resins are being used to substitute bitumen and improve requirements. Therefore, a deep understanding of the material behavior is required. This study presents the analysis of the relaxation behavior of a poly(methyl methacrylate)-based pavement and the influence of mineral fillers. An approach using a linear elastic–viscoelastic material model was selected based on evidence and validated across the linear and nonlinear deformation range. The results reveal no influence of the mineral fillers on the relaxation behavior. The presented modification of the linear elastic and viscoelastic modeling reveals accurate results to predict long-term pavement performance. This approach offers a practical method for forecasting asphalt behavior. Further research is needed to incorporate deformation behavior into the model.

The track system traditionally used in tramway track design is 59Ri2. Due to technical progress, the rigidity of modern flexible track structures has become sufficiently rigid and durable, and as a result, track systems with much lower inertia, such as Ts52, have also appeared. The use of the 59Ri2 rail system continues to dominate in embedded rail structures, which is not only statically oversized, but also significantly increases the amount of pouring material used, considering that both rail systems are suitable to carry road rail loads and their service life is considered similar (same wear allowed). This is not only an economic issue, but also a manufacturing and logistical one. Due to the scarcity of resources, a greater length of track can be built at unit cost by minimising the use of materials, and the amount of pouring material available on the market has been periodically limited in recent years. In this article, we use the side results of our previous finite element models to show the impact of track system dimensions on the amount of pouring material, and also detail the extent of material savings with PVC pipes and concrete material saving blocks.

The revenues of the railway infrastructure managers are proportional to the volume of the traffic on the railway lines, supplemented by other revenues and subsidies. To maximise their revenues in a changing economic environment (where there is a tendency for the state to withdraw from funding), it is important to have and operate an infrastructure with sufficient capacity. In the event of inadequate track conditions, they will not only face a loss of revenue from network charges, but also additional penalty costs. One of the key elements in achieving stable, good track condition is to ensure that the formation conditions are adequate. In practice, the use of large-scale mechanised subgrade rehabilitation is becoming increasingly common, ensuring a sufficiently fast job and consistent quality. Another advantage of its technology is that it allows 100% of the logistical tasks of renewal to be carried out on the track and reduces the amount of new raw materials to be installed. In this article, we will present the application possibilities of large-scale mechanised subgrade rehabilitation and highlight the savings in newly installed raw materials. With this thought-provoking article, we aim to raise the interest of the professional audience to learn more about this technology.