Failure analysis, composites

Materials Algorithms Project Source of algorithms usefiil for modeling material behavior, http //www. msm.cam.ac.uk/map/rrrapmain.html Materials Properties Handbooks Operation Distributes the Aerospace Structural Metals Handbook, the Structural Alloys Handbook, the Damage Tolerant Design Handbook, and the Composite Failure Analysis Handbook, http // www.purdue.edu/MPHO... 

Laser ionization mass spectrometry or laser microprobing (LIMS) is a microanalyt-ical technique used to rapidly characterize the elemental and, sometimes, molecular composition of materials. It is based on the ability of short high-power laser pulses (-10 ns) to produce ions from solids. The ions formed in these brief pulses are analyzed using a time-of-flight mass spectrometer. The quasi-simultaneous collection of all ion masses allows the survey analysis of unknown materials. The main applications of LIMS are in failure analysis, where chemical differences between a contaminated sample and a control need to be rapidly assessed. The ability to focus the laser beam to a diameter of approximately 1 mm permits the application of this technique to the characterization of small features, for example, in integrated circuits. The LIMS detection limits for many elements are close to 10 at/cm, which makes this technique considerably more sensitive than other survey microan-alytical techniques, such as Auger Electron Spectroscopy (AES) or Electron Probe Microanalysis (EPMA). Additionally, LIMS can be used to analyze insulating sam-... 

J. Scheirs, Compositional and Failure Analysis of Polymers. A Practical Approach, John Wiley Sons, Ltd, Chichester (2000). 

A comprehensive review of compositional and failure analysis of polymers, which includes many further examples of analysis of contaminants, inclusions, chemical attack, degradation, etc., was published in 2000 [2], It includes details on methodologies, sampling, and sample preparation, and microscopy, infrared spectroscopy, and thermal analysis techniques. 

Beaumont P.W.R. and Anstice P.D. (1980). A failure analysis of the micro-mechanisms of fracture of carbon fiber and glass fiber composites in monotonic loading. J. Mater. Sci. 15, 2691-2635. 

Wells J.K. and Beaumont P.W.R. (1982). Construction and use of toughness maps in a fracture analysis of the micromechanisms of composite failure. In Composite Materials Testing and Design. ASTM STP 787 (I.M. Daniel ed.), ASTM, Philadelphia, PA, pp, 147-162. 

Wilkins, D.J. (1983). Failure analysis and mechanisms of failure of fibrous composite structures. NASA CP-2278, 67-93. 

PLASTEC is one of 20 information analysis centers sponsored by the Department of Defense to provide the defense community with a variety of technical information services applicable to plastics, adhesives, and organic matrix composites. For the last 21 years, PLASTEC has served the defense community with authoritative information and advice in such forms as engineering assistance, responses to technical inquiries, special investigations, field trouble shooting, failure analysis, literature searches, state-of-the-art reports, data compilations, and handbooks. PLASTEC has also been heavily involved in standardization activities. In recent years, PLASTEC has been permitted to serve private industry. 

The failure analysis can be done using a judicious combination of several methods such as visual examination, metallography, microscopy, electron microprobe, energy dispersive X-ray analysis, X-ray diffraction methods for determining residual stress in the sample, surface analytical techniques to determine the nature and composition of surface deposits and finite element analysis modeling. 

Testing of the composites themselves, or portions of them, are only one part of elevated temperature testing. Other areas requiring attention include failure analysis, damage accumulation, nondestructive evaluation, micro-structural evaluation, and information needed to validate predictive models. Chapter 4 refers to modeling efforts which require the collection of data on the constituents of the composites, i.e., the starting fibers, the matrices, and the fiber-matrix interfacial materials, to make predictions for properties of real composites. To use the models described previously, one must also know about the properties of the individual components. These issues are addressed in this section. 

The mechanism of adhesion is also an important factor in failure analysis in composites [31]. Some adhesives work due to a physical entanglement of the resin into the wood structure whereas others require a free hydroxyl group on one of the cell wall polymers to participate in a chemical reaction with the resin. Substitution of hydroxyl groups was shown to decrease adhesion between chemically modified veneers due to the loss of hydroxyl functionality [32]. Resins that are water-soluble and depend on a hydrophilic substrate for penetration will be less efficient in chemically modified wood due to the decreased hydrophilic nature of the celt wall resulting from modification [33]. 

Acta Metallurgica et Materialia Cement and Concrete Research Composite Structures Computers and Structures Corrosion Science Engineering Failure Analysis Engineering Fracture Mechanics European Journal of Mechanics A B International Journal of Fatigue International Journal of Impact Engineering International Journal of Mechanical Sciences International Journal of Non-Linear Mechanics International Journal of Plasticity... 

Figure 1.39 Polarized light micrograph of crystallized high density polyethylene (HDPE). (Reproduced with permission from J. Scheirs, Compositional and Failure Analysis of Polymers A Practical Approach, John Wiley Sons Ltd, Chichester. 2000 John Wiley Sons Ltd.)...

Scheirs, J. (2000) Compositional and Failure analysis of Polymers, Chichester John Wiley... 

Polymers are often used in conjunction with other materials as composites. The most familiar types are the fiber-filled composites such as fiberglass and the carbon-, boron-, or Kevlar-filled advanced composites. Granular-filled composites such as those using clay as extenders in some plastics or ground quartz added to dental plastics to increase their wear resistance also represent an important class of materials. In these cases the presence of a second phase as well as the interface between polymer and filler increases the complexity of the failure analysis. 

Material Composition 1. Analysis of composition of the polymer and additives 2. Degree of crystalhnity, molecular weight, molecular weight distribution, and degree of fusion 3. Identification of contaminants at the failure point 4. Surface analysis... 

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