Committee V.1: Accidental Limit States

Concern for accidental scenarios for ships and offshore structures and for their structural components leading to limit states. Types of accidental scenarios shall include collision, grounding, dropped objects, explosion, and fire. Attention shall be given to hazard identification, accidental loads and nonlinear structural consequences including strength reduction, affecting the probability of failure and related risks. Uncertainties in the use of accidental scenarios for design and analysis shall be highlighted. Consideration shall be given to the practical application of methods and to the development of ISSC guidance for quantitative assessment and management of accidental risks

The Sandia Fracture Challenge: blind round robin predictions of ductile tearing

Existing and emerging methods in computational mechanics are rarely validated against problems with an unknown outcome. For this reason, Sandia National Laboratories, in partnership with US National Science Foundation and Naval Surface Warfare Center Carderock Division, launched a computational challenge in mid-summer, 2012. Researchers and engineers were invited to predict crack initiation and propagation in a simple but novel geometry fabricated from a common off-the-shelf commercial engineering alloy. The goal of this international Sandia Fracture Challenge was to benchmark the capabilities for the prediction of deformation and damage evolution associated with ductile tearing in structural metals, including physics models, computational methods, and numerical implementations currently available in the computational fracture community. Thirteen teams participated, reporting blind predictions for the outcome of the Challenge. The simulations and experiments were performed independently and kept confidential. The methods for fracture prediction taken by the thirteen teams ranged from very simple engineering calculations to complicated multiscale simulations. The wide variation in modeling results showed a striking lack of consistency across research groups in addressing problems of ductile fracture. While some methods were more successful than others, it is clear that the problem of ductile fracture prediction continues to be challenging. Specific areas of deficiency have been identified through this effort. Also, the effort has underscored the need for additional blind prediction-based assessments

Investigation of the effect of forming parameters in incremental sheet forming using a micromechanics based damage model

The incremental sheet forming (ISF) process is considered as a feasible solution for forming a variety of small batch and even customised sheet components. The quality of an ISF product is affected by various process parameters, e.g. sheet material, step-down, feed rate, tool diameter and lubricant. To produce an ISF part of sufficient quality and accuracy without defects, optimal parameters of the ISF process should be selected. In the present work, experiments and FE analyses were conducted to evaluate the influence of the main ISF process parameters including the step-down, feed rate and tool diameter on the formability and fracture of two types of pure Ti (grade 1 and 2). The Gurson–Tvergaard-Needleman (GTN) damage constitutive model with consideration of stress triaxiality was developed to predict ductile fracture in the ISF process due to void nucleation, growth and coalescence. It was found that the ISF parameters have varying degrees of effect on the formability and fracture occurrence of the two types of pure Ti, and grade 2 pure Ti sheet is more sensitive than grade 1 Ti sheet to the forming parameters due to low ductility

ISSC 2022 Committee III.1-Ultimate Strength Benchmark Data

Overview This page provides a zip file for a benchmark study by the 21st International Ship and Offshore Structures Congress (ISSC) Committee III.1-Ultimate Strength. The files include test details, drawings, material data, geospatial measurements, and results for ultimate strength tests on a newly built grillage, ATC-1 that have been generated by Naval Surface Warfare Center Carderock Division under funding from the US Navy's Office of Naval Research (ONR) Advanced Naval Platforms Division under the direction of Dr. Paul Hess. The folder “General Information” contains a detailed description of the study as well as a presentation on the experimental setup. Folder Structure General Information: Contains the study description, experimental setup, fabrication drawings Phase 1: Files distributed under Phase 1 of the study, namely a CAD model (IGES and STEP) and nominal data on the grillage properties Phase 2: Files distributed under Phase 2 of the study, namely data on measured (actual) structural properties as well as metrological data (point clouds) describing the as-constructed grillage shape Phase 3: Files distributed under Phase 1 of the study, namely precise thickness measurements, material acceptance certificates, and tensile test results Result: Load-shortening data for the ATC-1 grillage as well as test video Photos: Photos of the ATC-1 grillage at various phases in the testing cycle Release and Distribution of Data The information is approved for public release with unlimited distribution per DoDI 5230.24. Usage of this data is unlimited. Unless required by applicable law or agreed to in writing, the data is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied and the US Government shall not be held liable for its use or misuse. Support Questions regarding this data should be forwarded to either: Paul Hess, // [email protected] Office of Naval Research Ken Nahshon // [email protected] Naval Surface Warfare Center Carderock Divisio