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LFB/CDT-2-2010: Intro to Plasticity for Analysts A background that includes vectors, matrix algebra, differential equations, basic numerical methods and basic engineering mechanics/physics is assumed. This is the second in a series of short courses by the author. The instructor’s first short course Lagrangian Hydrocodes is highly recommended as a prerequisite but not necessary for participants with related background. Participants should also be familiar with using some analysis code whether Lagrangian, Eulerian or ALE based, as well as a
desire to better understand the materials, physics, numeric and computational aspects that make up these fairly complex material/constitutive models in both explicit and implicit analysis codes.
The objective of this 3 day course is to focus on the plastic behavior of engineering materials as implemented in modern computational analysis codes, the basic assumptions made and their limitation, and specific
plasticity models pertinent to problems of interest. Plastic material behavior (constitutive) models are available and heavily used in both hydrocodes (explicit wave codes) as well as implicit structural dynamics
codes. Participants will learn: some of the pertinent aspects of metallurgy to better understand plastic behavior at the material level; calculation of the invariants and principal directions for the stress and strain tensors; a fairly detailed 1D and then a 2D/3D development of the governing plasticity incremental equations and their time integration; rate dependency and details of some very pertinent plasticity models for metals, concrete, rocks, ceramics and soils; a discussion of damage; a
discussion of shear bands; and finally a fairly complete development of an actual elastic-plastic material model that is being used in a commercial code. Modern plasticity modeling is a fairly complex subject with several important ingredients. There are few if any textbooks and short courses available that adequately cover this area, especially in the problem space
of highly transient and non-linear applications, that provide both a solid introduction (which includes basic material behavior) and a discussion of the important computational aspects. The critical importance of specialized materials testing to calibrate various plasticity models for different materials will also be discussed. An additional objective of this short course is to provide a brief materials background and answer basic questions relating to: what is important, why is it important, what
does it mean and especially how does it all fit together computationally.
The dynamic behavior of modern structures and materials subjected to very transient loadings can be quite complex, especially when some sort of failure is precipitated. The accurate modeling of the highly non-linear material behavior is a crucial ingredient to an accurate analysis. Metals, ceramics, concrete, rocks and many soils are routinely modeled using plasticity theory. Pertinent problem applications for such analysis software includes: impact of objects, design and analysis of structures,
as well as military applications such as the design and simulation of weapon systems and their effects on targets. In general, participants will gain a more basic understanding of plastic material behavior as modeled within modern analysis codes that will assist them in becoming more knowledgeable analysts.
Dr. Carl T. Dyka received his Ph.D. in Engineering Mechanics in 1978 from the University of Connecticut. He received his MS in Structural Engineering in 1974 and BS in Civil Engineering in 1973 both from the University of Massachusetts. He has been an analyst for the Naval Surface Warfare Center (NSWC) since 2000.
Currently he is a senior analyst in the Lethality and Effectiveness Branch at NSWC-Dahlgren, in Dahlgren, VA. During most of the 1990's, he was a researcher in computational mechanics at the Naval Research Laboratory in Washington, DC. In the 1980's, Dr. Dyka was an analyst and finite element developer/researcher for the Electric Boat Division of General Dynamics in Groton, CT. During the 1980's and into the early 1990's he was also an adjunct professor at the University of Connecticut and taught several different graduate courses. Dr. Dyka has wide experience in computational mechanics that includes: R&D in finite element and constitutive relations, boundary element, particle methods, structural acoustics, fluid-structure interaction; extensive analysis experience using several widely know analysis codes; teaching at the graduate course level as well as at the short course level; and a significant amount of commuter programming and code development. He is recognized by the both the DoD and DOE as a national level expert in Computational Structural Mechanics. Currently Dr. Dyka serves in an advisor capacity to High Performance Computing (HPC) as the Computational Technology Area (CTA) in Computational Structural Mechanics. HPC has a total of ten CTA's covering the computational and applications spectrum of interest for the DoD. The CTA's function as an advisory board to top level HPC management.
PREREQUISITES
COURSE OBJECTIVES AND SCOPE
