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Additively manufactured parts are often created with cavities for weight reduction or other mechanical purposes. These cavities offer the optimal base for granular damping. Unfused raw material particles can be left inside the structure or another granular material can be filled in to increase structural damping. In this paper, a simple mechanical model is developed based on measurements of a basic experiment for granular damping with only a small amount of particles.

Reliable knowledge of a ship’s position and movement in relation to other traffic participants and obstacles is a fundamental requirement for navigation and avoiding collisions and groundings. Consequently, the onboard provision of resilient position, navigation and time data (PNT) is emphasized by the International Maritime Organization’s (IMO) e-navigation strategy, solution S3 “Improved reliability, resilience and integrity of bridge equipment and navigation information” and by the assigned risk control option RCO5 “Improved reliability and resilience of onboard PNT systems”. An initial step towards resilient PNT has been realized by the maritime community with the development of the performance standards for shipborne multi-system radionavigation receiver equipment (MRR). This MRR performance standard (PS) supports the full use of data coming from current and future radionavigation systems and services. Consequently, the combined use of several global navigation satellite systems (GNSS) and the additional use of space based augmentation systems (SBAS) as well as optional terrestrial radionavigation systems (e.g. eLoran or R-Mode) will be supported to increase the performance of positioning and timing. As a second step, the development of guidelines for an onboard PNT (data processing) unit has been identified as supplementary and necessary. The starting point is the onboard use of a combination of GNSS receivers and autarkic systems (e.g. radar, gyro, echosounders with bathymetric data) for a comprehensive provision of required PNT data. Redundancy in the available data enables the application of integrity monitoring functions to evaluate the current usability of safety-critical data and components. The aim of the guidelines is the specification of data processing rules towards the resilient provision of standardized PNT data and integrity information. For this purpose, a modular architecture for an onboard PNT system is introduced and scaled to the need for data input as well as the performance of data output.

A reliable knowledge of ship’s position and movement in relation to other traffic participants is necessary for safe navigation at sea. A prerequisite to avoid collisions and groundings is the resilient onboard provision of position, navigation, and time data. This is emphasized by e-navigation solution S3 “Improved reliability, resilience and integrity of bridge equipment and navigation information” and assigned risk control option RCO5 “Improved reliability and resilience of onboard PNT systems” (NCSR1/9). In recent years the modular and open concept of an integrated PNT system has been developed as framework for the coordinated enhancement of the maritime PNT system (NAV58/6/1, NAV58/INF5, NCSR1/9/2). The Performance Standard for multi-system shipborne radionavigation receiver equipment, highlighted in this concept and currently under development (NCSR1/10), provides the basis to enable the full use of data coming from current/future radionavigation systems/services (e.g. range measurements, system parameters and variables such as orbit, correction and augmentation data). Furthermore the concept recognises the demand of an onboard PNT Unit as a synonym for a shipborne data processing tool to facilitate the application of multi-system-/multi-sensor-based techniques for resilient provision of all PNT data and reliable monitoring of data and system integrity (NAV58/6/1, NAV58/INF5, NCSR1/9/2). The combined use of PVT relevant sensors (e.g. GNSS Receiver, DGNSS corrections, Multi-Radionavigation Receiver) and onboard systems (e.g. Radar, Gyro, Echosounder with bathymetric data) establishes the needed redundancy to enable the monitoring of data and system integrity and to improve the performance of provided PNT data. This enables the protection of the onboard process of PNT data generation (cybersecurity) against intrusions by malicious actors. Therefore the drafting of a Guideline for the PNT Unit is considered as a supplementary but necessary step in the overall PNT system development for e-navigation solution S3 and associated risk control option RCO5. Reliability, integrity and resilience are fundamental requirements on nautical onboard equipment/systems identified as user needs and addressed as high-priority solution in the frame of e-navigation. If the PNT data provision meets these fundamental requirements or not can only be evaluated with respect to specific sets of technical requirements. To determine the achieved degree of reliability it is necessary to specify the tasks/functions to be performed by the equipment/system, the nominal operating conditions incl. dependencies on external systems/services and the required interruption free period of time. To achieve standardized results for integrity evaluation it is necessary to specify the methods of integrity monitoring in an unambiguous manner. And to ensure resilience it is necessary to identify the demand on intrasystem error compensation in relation to specified tasks, functions and performance requirements. The development of a guideline for the onboard PNT Unit is an appropriate measure to point out and clarify the dependencies between available/usable system modules (e.g. sensors, services, data sources) the applicability/feasibility of system operation (tasks, functions) and the achievable quality of data products.