Henry Tan's blog

Quiz: Heat Treatment - Quenching & Tempering

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Conventional heat treatment procedures for producing martensitic steels generally involve continuous and rapid cooling of an austenitized specimen in some type of quenching medium, such as water, oil, or air. The properties of a steel that has been quenched and then tempered depends largely on the rate of cooling and tempering times and temperatures. During the quenching heat treatment, the specimen can be converted to a variety of microstructures including soft and ductile spheroidite to hard and brittle martensite. The production of pearlitic and bainitic steels is lower in cost and suffices for most applications. Martensitic steels must be tempered prior to use due to their extreme brittleness. A range of heat treatments producing a variety of microstructures and mechanical properties will be investigated in this experiment beginning with a set of initially equivalent samples of SAE 1040 steel. Pearlite, Bainite and Martensite will all be produced through variations in the cooling rates of initially austenized samples.

This blog focuses on the micromechanics modeling of composite materials.

H. Tan, 2003
Chapter 12, Combined atomistic and continuum simulation for fracture and corrosion

Comprehensive Structural Integrity (http://www.sciencedirect.com/science/referenceworks/0080437494)
Volume 8: Interfacial and Nanoscale Failure

This blog focuses on viscoelasticity (http://en.wikipedia.org/wiki/Viscoelasticity)

Interetsed topics include:

• Material Point Method, eXtended Finite Element Method, and other mesh-free methods;
• Combined atomistic and continuum simulations;
• Multiscale homogenization.

Links to other blogs:

Lecture note 14: MPM Homework

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lecture note 13: Interpolating Shape Functions

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lecture note 12: Material Point Method: 2D problems

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Map from particles to grids
Interpolate from grid to particles
Constitutive models
Boundary conditions

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Material Point Method:
Grid Equations
Mass matrix
Lumped mass matrix

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Variational principle
Particle discretization
Grid interpolation

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Quiz: Precipitation Hardening of Aluminum Alloys

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The strength and hardness of some metal alloys may be enhanced by the formation of extremely small
uniformly dispersed particles of a second phase within the original phase matrix; this must be accomplished
by appropriate heat treatment.

Quiz: Mechanical Testing- Tensile Testing

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The mechanical properties of a material are directly related to the response of the material when it's subjected to mechanical stresses. Since characteristic phenomena or behavior occur at discrete engineering stress and strain levels, the basic mechanical properties of a material are found by determining the stresses and corresponding strains for various critical occurrences.

Quiz: Mechanical Testing- Impact & Hardness Testing

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The mechanical properties of materials are ascertained by performing carefully designed laboratory experiments that replicate, as nearly as practical, the service conditions.

The X-Ray diffraction technique is used to determine the crystal structure and interatomic spacing of crystallinesamples through constructive interference of reflected x-ray beams.

Bragg's Law and X-Ray diffraction data, in combination with the expressions for interatomic spacing in terms of the lattice parameter and Miller indices for acrystal, can be utilized to identify crystal structures, determine lattice constants, and locate defects within astructure.

In the spring semester of 2002, Dr. Woldesenbet and I gave a hand-on laboratory course:Materials of Engineering Laboratory, to the junior undergraduate students at the Louisiana State University. In this Blog, I am also adding some state-of-the-art techniques for materials laboratory.

Class schedule:

Granular materials deserve being investigated as this has been the case with liquids, gases and elastic materials.

cellular metal: space is divided into distinct cells. The boundaries of these cells are made of solid metal, the interior are voids. Ideally, the individual cells are all separated from each other by metal but often this restriction is relaxed

塑料粘结炸药are composites containing energetic grains, ranging in size from less than one to a few hundred micrometers, embedded in a matrix of high-polymer binder.

Experimentally, loading to a mechanical system can be applied either through the displacement control or the force control.

However, the responses of the system can only be measured in displacements, and hence strains.