On the material characterization of a composite using micro CT image based finite element modeling

Abstract

Novel techniques for generating robust and accurate meshes based on 3-D imaging data have recently been developed which make the prediction of macro-structural properties of composite structures based on micro-structural composition straightforward. The accuracy of reconstructions is a particular strong point of these new techniques with geometric accuracy only contingent on image quality. Algorithms developed and used are topology preserving, volume preserving and multi-part geometric models can be handled straightforwardly. In addition to modeling different constituent materials as separate mesh domains, material properties can be assigned based on signal strength in the parent image thereby providing a way of modeling continuous variations in properties for an inhomogeneous medium. These new techniques have been applied to the analysis of a ceramic matrix composite which was micro-CT scanned and the influence of imaging parameters on both predicted bulk properties and localized stresses has been explored.This paper utilizes the Computed Tomography (CT) as the NDE technique to characterize the initial matrix porosity's locations and sizes in a Ceramic Matrix Composites (CMC) test specimen. Further, the Finite Element (FE) method is applied to calculate the localized stress field around these pores based on the geometric modeling of the specimen's CT results, using image analysis, geometric modeling and meshing software, ScanIP/ScanFE [1]. The analyses will simulate experimental loading conditions where scanned specimens are then tensile tested to a 0.07 % total strain to identify the matrix cracking locations in relation to the original pores. Additional work is carried out combining the image processing and finite element to investigate the applicability of some novel meshing techniques. Finally, the calculated Finite Element [2-4] localized stress risers are compared with the observed matrix cracking locations. This work is expected to show that an FE model based on an accurate 3-D rendered model from a series of CT slices is an essential tool to quantify the effects of internal macroscopic defects of complex material systems such as CMCs. INTRODUCTIONThe CT technique was initially implemented in the medical field in the early 1970's, but has gained recognition as an important tool in the material research area as a viable NDE technique to measure volumetric information such as dimensions, voids, inclusions, and density variations, within a solid and to provide pictorial views of the internal and external structure of materials [7]. The most important advantage of the CT is the possibility of an accurate 3-D visualization and quantification of the internal structure of materials using a series of 2-D cross-sectional CT images. Several material researchers went beyond simple image analysis and quantitative image assessment, and used the 3-D accurate visualization to generate a finite element model to calculate the localized stress and strain field around the observed internal material defects [8]. Such an anal...

An efficient approach to converting three-dimensional image data into highly accurate computational models

“…More recently, the use of these images as the basis for generating finite-element and finite volume models for use in physics-based simulations has gained ground (Abdul-Aziz et al 2006;Berre et al 2006;Watson et al 2006;Notarberardino et al 2008).…”

NDE using sensor based approach to propulsion health monitoring of a turbine engine disk

“…However, development and implementation of such sensor technology and diagnostic capabilities is dependent upon performing combined analytical and experimental studies (coupon and sub-scale levels) to determine their applicability and success. Attempts are under way to develop technologies that include high temperature, wireless, low-cost, durable sensors for a wide variety of applications [1][2][3][4][5]. Though, many challenges, such as issues associated with hot structural life management which includes materials that are strongly influenced by geometry, loading conditions and anisotropy will have to be addressed to achieve these goals.…”

Nondestructive Evaluation and Mechanical Characterization of a Defect‐Embedded Ceramic Matrix Composite Laminate

“…With the aid of the NDE methods, possible production defects such as delaminations, pores, and cavities, and so forth, as well as component conditions before and after testing can be detected. 13,[18][19] Previous studies by Ellingson and others have detected much smaller flaws such as matrix porosity, voids, microcracks, and delaminations with CT or micro-CT technology, [20][21][22][23][24] through which some analytical models (e.g., finite element) have been established to simulate and calculate localized stress field, as well as stress concentration, around the detected internal defects. [7][8] At NASA, advanced digital radiography, high-resolution computed tomography (CT), thermography, ultrasound, acoustic emission, and eddy current systems have demonstrated the maturity and success for application to shuttle wings, airline rudders and tails, thruster chamber assemblies, combustion liners, and other composite components.…”

“…The focus and objective of this investigation is to prepare a so-called defect catalog that can serve as a reference for the application of the different methods. [21][22][23] In addition, CT has been used on CMCs to illustrate defect information that might affect mechanical behavior and to analyze structural and damage changes of CMCs under mechanical loading. [12][13][14][15][16][17] Among the advanced NDE methods, X-ray CT is broadly applicable to any material or test object through which a beam of penetrating radiation may be passed and detected, including metals, plastics, ceramics, metallic/nonmetallic composites, and assemblies.…”