MMS 190 – MPMOB Methods for risk and reliability analysis#

Method for reliability and risk analysis

ORGANISATION OF THE COURSE: EXAMINER AND TEACHERS The course is given by the Division of Marine Technology on the Department of Mechanics and Maritime Sciences, Chalmers University of Technology in Gothenburg, Sweden.

  • Examiner and Lecturer: Wengang Mao

    Phone: 031–772 1483; E-mail: Wengang.Mao@chalmers.se

  • Tutorials, Tutorial-R and Assignments:

Wengang Mao Phone: 031–772 1483 E-mail: Wengang.Mao@chalmers.se

Eligibility#

General entry requirements for Master’s level (second cycle) Applicants enrolled in a programme at Chalmers where the course is included in the study programme are exempted from fulfilling the requirements above. Specific entry requirements English 6 (or by other approved means with the equivalent proficiency level) Applicants enrolled in a programme at Chalmers where the course is included in the study programme are exempted from fulfilling the requirements above. Course specific prerequisites Mathematics (including mathematical statistics, numerical analysis and multi-variable calculus), mechanics and strength of materials and engineering materials

Aim#

The course gives the student knowledge and tools how to design marine structures with regard to limit state based approaches by means of probability and risk analysis approaches. A variety of simplistic and advanced methodologies are compared with objective to demonstrate their advantages and limitations. Realistic and typical examples for marine structures are used throughout the course in order to introduce the student to real examples with their challenges of complexity which require solid and well-motivated assumptions.

Learning outcomes (after completion of the course the student should be able to)#

After finishing the course, students will have good knowledge and understanding of how to carry out risk and reliability analysis of mechanical systems. More specifically, the student should be able to:

  • use and interpret design rules and standards in order to analyze risk and reliability levels according to given design criteria and safety measures

  • carry out reliability analysis for specific mechanical system components

  • demonstrate which is the most appropriate methodology to use in a risk and reliability analysis for certain practical engineering problems with respect to mechanical system safety

  • understand and discuss the advantages and limitations using FORM, SORM and other simulation method for reliability analysis

  • and critically evaluate and compare various design concepts with respect to reliability and safety of engineering systems.

INTRODUCTION TO AND CONTENTS OF THE COURSE#

It is well recognised that limit state-based approaches for marine structures are much better methodologies for structural design and strength assessment than traditional working stress-based approaches, the latter typically being formulated as a fraction of material such as yield strength. This is the situation because it is not possible to determine the true margin of structural safety as long as limit states remain unknown. A limit state is defined as a condition under which a particular structural component or an entire structural system fails to perform its designated function. Four types of limit states are relevant: serviceability limit state (SLS), ultimate limit state (ULS), fatigue limit state (FLS) and accidental limit state (ALS).

The course focuses on the risk and reliability analysis of the FLS and ULS criteria for ships and offshore structures. These criteria include the failure of critical components of the structure caused by metal fatigue due to cyclic loading, exceeding the ultimate strength (in some cases reduced by repetitive actions) by any combination of buckling, yielding, rupture or fracture, or the transformation of the structure into a mechanism associated with buckling collapse or excessive deformation. The course is divided into four parts as follows:

  • Introduction to limit state approaches

Definition of limit states: definitions and stochastic variables Application of limit states in the design of marine structures: design criteria according to classification rules.

  • Statistics theory

Statistical distributions. Methods for uncertainty analysis.

  • Probabilistic methods

First order reliability methods (FORM). Second order reliability methods (SORM). Simulation methods (Monte Carlo).

  • Reliability and risk analysis in limit states design

Three mandatory computer assignments will be carried out where the student will practice gained knowledge during the course on realistic and typical examples for marine structures.

ASSIGNMENTS#

The course has three mandatory assignments where the student will practice gained knowledge during the course on realistic and typical examples for marine structures. Students should form groups of 3-4 students to solve each of the assignments. Reports on each of the assignments should be sent in by e-mail to both teachers (see dates below). The report should be written using a report template that can be downloaded from the course’s web page on Ping-Pong.

  • Assignment 1: Fitting distribution and linear regression analysis. Deadline: 17.00 on the 22nd of April

  • Assignment 2: Monte Carlo methods for reliability analysis. Deadline: 17.00 on the 12th of May

  • Assignment 3: Extreme prediction for limit state design. Deadline: 17.00 on the 26th of May

EXAMINATION#

A passed course gives the student 7.5 hp. The examination is performed by a mandatory written exam and through the three project assignments (report and presentation seminar). Note that all the three assignments (report and presentation) must have been approved before the written exam! The grading is performed solely by the written exam (Bonus points from the assignments will be added to the score of the written examination!).

The written examination takes place June 3, 2021.#

  • The student is allowed to bring the compendium to the exam. Some minor notes in the compendium are allowed, however, additional papers with notes are NOT allowed.

  • Any electronically calculator is allowed.

  • The written exam consists only the problem-solving part. Hence, the maximum number of points on the exam is 30 points.

  • The different grades given are (sum of points on the exam: grade): 0 – 14: Fail of exam; 15 – 19: 3; 20 – 25: 4; 26 – 30: 5.

COURSE SCHEDULE (Attention!!)#

Due to the current condition of Coronavirus spreading worldwide, we are advised to teach this course through the digital learning tool i.e., Zoom.

• Lecture & Tutorial (Zoom digital classroom): presentation of theory with reference to chapters in the compendium, and examples suitable for hand calculations. • Computer exercises (Zoom digital classroom): computer exercises. These occasions are “warm-ups” for the Assignments. Active participation and preparations in advance are strongly recommended! • Assignments (Zoom digital classroom): practical engineering projects.