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Probabilistic Mechanic and Reliability Engineering

 

PULSTR and PROBSTRA

Under the sponsorship of NSWCCD, GEM’s personnel have developed various probabilistic analysis and reliability-based design tools for naval ship structures. The PULSTR tool is developed by integrating the ultimate hull strength assessment module with a probabilistic analysis framework. The GUI version of PULSTR (VBPULSTR) is developed to streamline and standardize input and execution processes. VBPULSTR can perform both the ultimate strength and the 1st failure based reliability assessment of a ship hull subjected to either hogging and sagging. The key features of PULSTR and VBPULSTR are demonstrated below.  
 
 
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Figure 1: Integration of the ULTSTR Deterministic Solver with a Probabilistic Analysis Framework



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Figure 2: Overview of PULSTRA Tool for Probabilistic Assessment of Ultimate Hull Strength



In addition to the development of the probabilistic version of ULTSTR code, GEM’s personnel have developed PROBSTRA which is a probabilistic version of SPECTRA. The PROBSTRA tool allows designers to perform uncertainty assessments of the combined wave and whipping induced bending moment (MWD) for a given probability of exceedance. The uncertainties associated with general hull parameters, response amplitude operators (RAOs), and whipping parameters are propagated through the SPECTRA deterministic solver. The statistical model of MWD generated from PROBSTRA’s Monte Carlo simulation module can be used in PULSTR for the reliability assessment of a hull girder under longitudinal bending. 
 
 
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Figure 3: Failure Location and Failure Mechanism of a Single Hull Subjected to Sagging



Reliability-Based Design of Surface Ships

Under the sponsorship of ONR, GEM’s personnel have implemented a reliability based design methodology for surface ships subjected to random seaway and extreme dynamic loading. A project overview is illustrated below. 
 
 
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Figure 4: Overview of Probabilistic Ship Analysis and Vulnerability Assessment Tool



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Figure 5: Illustration of Solution Modules for Reliability-Based Analysis and Design of Single and Double Hulls




GEM Capabilities


Computational Mechanics

Composite Mechanics

Fatigue and Fracture

Probabilistic Mechanics and Reliability Engineering

Stochastic Mechanics


 

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