Influence of Freeze-Thaw Aging on the Impact Performance of Damped Carbon Fiber Reinforced Plastics for Automotive Applications

The increasing use of composite materials in the automotive field requires more attention with regards to the appearance of noise, vibration and harshness (NVH) study in cars construction. However, in car door panels production, impact characteristics need to be evaluated in sandwich laminates. Furthermore, it is important to consider the effect of prolonged environmental aging on crashworthiness properties. The innovative content of the work is the hygrothermal effects evaluation on impact performance for two damped CFRP sandwich laminates. In this paper, two damping materials, Kraibon HHZ9578/99 and SUT9609/24, were used as core between two skins of CFRP for sandwich composite production. Freeze-Thaw aging treatment according to IEC 60068, specific for Automotive, was performed to investigate environmental effects on components. Up to 750 h, it was demonstrated that water absorption is regulated by Fick’s Law. The low-velocity impact behavior of the damped sandwiches has been studied according to ASTM D7136 throughout drop dart test equipment. Both main peak forces and energy absorption characteristics are negatively affected by aging condition. The introduction of damping core inside the composite structure of vehicle components can satisfy NVH constrictions. By contrast, at least same operating conditions must be assured in relation to not-damped components

Band-Division vs. Space-Division Multiplexing: A Network Performance Statistical Assessment

We compare the networking merit of two possible multiplexing techniques on top of wavelength division multiplexing to enlarge transmission capacity: the band division multiplexing (BDM) that aims at using up to all the U-to-O low-loss transmission bands available on the G-652.D fiber and the spatial division multiplexing (SDM) implemented by activating additional fibers, used on the C-band only. We use the statistical network assessmemnt process (SNAP) to derive the networking performance as blocking probability vs. the total allocated traffic normalized with respect to the multiplexing cardinality. We analyze two network topologies: the German regional network and the US-NET continental network. In case dark fibers are available, SDM upgrades are always the best solution, enabling up to 12% and 17% of extra traffic at blocking probability equal to 10^{-3} on top of the multiplication by the multiplexing cardinality (N_{ ext{M}}) of 12, for the German and US-NET topology, respectively. BDM solutions present worse performance, but mixed BDM/SDM solutions display quite limited penalties with respect to the pure SDM solution, up to the use of 16 THz per fiber. So, mixed BDM/SDM implementation seems the most convenient solution in case of limited availability of dark fibers. Pure BDM solutions occupying a bandwidth larger than 16 THz display an increasingly and considerable gap in the allocated traffic with respect to the pure BDM, therefore, their use must be considered only in case of total absence of available dark fibers

QoT Computation for 100G Lightpaths Routed on 10G-loaded Dispersion-Managed Network Segments

The core and backbone optical network market segment is largely dominated by coherent transmission delivering 100Gbps and beyond thanks to the DSP-based coherent transceivers technology optical line systems without chromatic dispersion compensation. The metro and access segment instead is still often made of dispersion-compensated optical line systems operated with cheap 10G transceivers because of the still excessive CAPEX required to upgrade this segment to coherent technology. In the context of the gradual rise of SDN technology, aimed at dynamically, transparently and automatically managing and orchestrating optical networks, the ability to route 100G coherent channels through a section of dispersion managed network populated with legacy 10G channels enables more flexibility and CAPEX savings. In this work we propose a simple, fast and conservative quality-of-transmission estimator, tailored to the needs of a software module for optical path computation, able to estimate of the 10G-to-100G non-linear effects

Statistical assessment of open optical networks

In order to cope with the increase of the final user traffic, operators and vendors are pushing towards physical layer aware networking as a way to maximize the network capacity. To this aim, optical networks are becoming more and more open by exposing physical parameters enabling fast and reliable estimation of the lightpath quality of transmission. This comes in handy not only from the point of view of the planning and managing of the optical paths but also on a more general picture of the whole optical network performance. In this work, the Statistical Network Assessment Process (SNAP) is presented. SNAP is an algorithm allowing for estimating different network metrics such as blocking probability or link saturation, by generating traffic requests on a graph abstraction of the physical layer. Being aware of the physical layer parameters and transceiver technologies enables assessing their impact on high level network figures of merit. Together with a detailed description of the algorithm, we present a comprehensive review of several results on the networking impact of multirate transceivers, flex-grid spectral allocation as a means to finely exploit lightpath capacity and of different Space Division Multiplexing (SDM) solutions

Network Performance Assessment with Uniform and Non-Uniform Nodes Distribution in C+L Upgrades vs. Fiber Doubling SDM Solutions

Both spatial-division multiplexing (SDM) and band-division multiplexing (BDM) have been proposed to increase the traffic allocation in transparent optical networks. If available, SDM may take advantage of the already deployed dark fibers, otherwise BDM is a viable and cost-efficient solution by exploiting multiple bands on the deployed fibers just upgrading the required equipment. We assess the network capacity upgrades enabled by C+L BDM and fiber doubling SDM solutions as realistic upgrade scenario from a C-band only case, using the statistical network assessment process (SNAP). SNAP has been applied to the German, the US-NET and the COST networks by generating any-to-any traffic according to both an uniform or population-based joint probability density function. We show that both SDM and BDM upgrades double the network capacity, making the performances of the two solutions comparable

Testing TIP Open Source Solutions in Deployed Optical Networks

Standardization in optical networking enables operators to benefit from using open source components. We investigate quality of transmission of open source hard- and software in the Deutsche Telekom RandD SASER network and optimize the working point

Failure mode analysis on compression of lattice structures with internal cooling channels produced by laser powder bed fusion

Conformal cooling coils have been developed during the last decades through the use of additive manufacturing (AM) technologies. The main goal of this study was to analyze how the presence of an internal channel that could act as a conformal cooling coil could affect compressive strength and quasi-elastic gradient of AlSi10Mg lattice structures produced by laser powder bed fusion (LPBF). Three different configurations of samples were tested in compression at 25 °C and 200 °C. The reference structures were body centered cubic (BBC) in the core of the samples with vertical struts along Z (BCCZ) lattices in the outer perimeter, labelled as NC samples. The main novelty consisted in inserting a straight elliptical channel and a 45° elliptical channel inside the BCCZ lattice structures, labelled as SC and 45C samples respectively. All the samples were then tested in as-built (AB) condition, and after two post process heat treatments, commonly used for AlSi10Mg LPBF industrial components, a stress relieving (SR) and a T6 treatment. NC lattice structures AB exhibited an overall fragile fracture and therefore the SC and 45C configuration samples were tested only after thermal treatments. The test at 25 °C showed that all types of samples were characterized by negligible variations in their quasi-elastic gradients and yield strength. On the contrary, the general trend of stress-strain curves was influenced by the presence of the channel and its position. The test at 200 °C showed that NC, SC and 45C samples after SR and T6 treatments exhibited a metal-foam like deformation

Multi Bands Network Performance Assessment for Different System Upgrades

We investigate the capacity of a reference German network when employing band-division multiplexing (BDM) using C+L+S-bands and spatial-division multiplexing (SDM) in case of different nodes distribution scenarios. We show that BDM enables increasing the network capacity by up to almost 3 x with respect to C-band transmission only

Power control strategies and network performance assessment for C+L+S multiband optical transport

Spatial-division multiplexing (SDM) and band-division multiplexing (BDM) have emerged as solutions to expand the capacity of existing C-band wavelength-division multiplexing (WDM) optical systems and to deal with increasing traffic demands. An important difference between these two approaches is that BDM solutions enable data transmission over unused spectral bands of already-deployed optical fibers, whereas SDM solutions require the availability of additional fibers to replicate C-band WDM transmission. On the other hand, to properly design a multiband optical line system (OLS), the following fiber propagation effects have been taken into account in the analysis: (i) stimulated Raman scattering (SRS), which induces considerable power transfer among bands; (ii) frequency dependence of fiber parameters such as attenuation, dispersion, and nonlinear coefficients; and (iii) utilization of optical amplifiers with different doping materials, thus leading to different characteristics, e.g., in terms of noise figures. This work follows a two-step approach: First, we aim at maximizing and flattening the quality of transmission (QoT) when adding L-and rm L +rm S-bands to a traditional WDM OLS where only the C-band is deployed. This is achieved by applying a multiband optimized optical power control for BDM upgrades, which consists of setting a pre-tilt and power offset in the line amplifiers, thus achieving a considerable increase in QoT, both in average value and flatness. Second, the SDM approach is used as a benchmark for the BDM approach by assessing network performance on three network topologies with different geographical footprints. We show that, with optical power properly optimized, BDM may enable an increase in network traffic, slightly less than an SDM upgrade but still comparable, without requiring additional fiber cables