Accession Number:

ADA411546

Title:

Phenomenology and Numerical Analysis of Relaxation Properties and Failure of Materials with Defects under Dynamic Loading

Descriptive Note:

Final rept. 23 May 23 Sep 2002

Corporate Author:

RUSSIAN ACADEMY OF SCIENCES PERM INST OF CONTINUOUS MEDIA MECHANICS

Personal Author(s):

• Naimark, Oleg

Report Date:

2002-09-01

Pagination or Media Count:

69.0

Abstract:

Statistically based phenomenology of materials with typical mesoscopic defects is developed with the aim to link the behavior of defect ensembles with relaxation ability and failure of materials under dynamic loading and the elaboration of numerical codes for the simulation of fracture and plasticity dynamically loaded materials. Statistical approach allowed the definition of nonlinearity of thermodynamic potential and the description of plastic instability and damage localization as the generation of collective modes in defects ensemble. Experimental study was carried out to confirm the responsibility of these modes for the plastic relaxation and damage localization in dynamically loaded materials. These experiments included the framing and high speed recording of dynamics of crack propagation in PMMA, the investigation of strain-rate sensitivity of copper in the Hopkinson-bar tests, the scaling analysis of failure surfaces with the usage of the high-resolution interferometer. Original finite element code was developed and applied for the simulation of plate impact tests. The applicability of proposed phenomenology was estimated in the course of comparative analysis of plane wave propagation in copper in the framework of developed model, Bodner-Partom and Follansbee models. The analysis revealed the principal limitation of last models for the description of dynamically loaded materials due to the subjective role of the variables responsible for the defect evolution to the stress-strain variables.

Descriptors:

• *COMPOSITE MATERIALS
• *NUMERICAL ANALYSIS
• *FRACTURE(MECHANICS)
• *DEFECTS(MATERIALS)
• *DYNAMIC LOADS
• *RELAXATION
• STRESS STRAIN RELATIONS
• COMPUTERIZED SIMULATION
• THERMODYNAMICS
• FINITE ELEMENT ANALYSIS
• POLYMETHYL METHACRYLATE
• SENSITIVITY
• HIGH RESOLUTION
• CRACK PROPAGATION
• NONLINEAR SYSTEMS
• WAVE PROPAGATION
• COPPER
• SCALING FACTOR
• PLASTIC PROPERTIES
• RUSSIA
• RECORDING SYSTEMS
• NUMERICAL METHODS AND PROCEDURES
• STATISTICAL PROCESSES
• INSTABILITY
• PLANE WAVES
• INTERFEROMETERS

Subject Categories:

• Polymer Chemistry
• Laminates and Composite Materials
• Numerical Mathematics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE