Failure analysis

The function of a structural adhesive joint is to transmit an external load to the structural member. If the joint fails to function as it is intended, it will undergo damage or failure. The damage could be actual fracture of the structure, excessive elastic deformation, or excessive inelastic flow. The criteria for what constitutes structural failure depend on the performance requirements of the joint. The fundamental problem in the mechanics of adhesives and joints is to obtain some relationship between the loads applied to the joint and a parameter that will adequately describe the criteria for strucmral failure. The most common criterion for such failure of lap-type joints is actual fracmre of the joint. For a given combination of adherend and adhesive, the stress analyst must decide what the mode or theory of failure would be if the applied loads become large enough to cause failure. The decision as to which theory would realistically determine the mode of failure is usually based on past experience, or upon some form of experimental evidence.  

---

Mr. Port and Dr. Herro have made presentations at professional societies such as the Electric Power Research Institute (EPRI), NACE, ASM, the American Boiler Manufacturer s Association (ABMA), and the American Chemical Society (ACS). Together, the authors have completed more than 4700 failure analyses. 

CORROSION IN CHEMICAL AND PETROCHEMICAL PLANT 9 17 Table 9.3 Corrosion failures analysed by type (after du Pont (1%8 to 1971))... 

TG-DTA Characterisation of carbon black [149], flammability evaluation [64], polymer degradation studies [65], ageing studies [70-72], product control [77, 81], combustion performance [83], safety evaluation [83], antioxidation activity [68], pyrolysis of rubbers [82], thermal stability [67, 69, 76, 77], interfacial junctions in viscoelastic composites [78], weathering [72], vulcanisation [73], oxidative behaviour [79], materials evaluation [80], failure analyses [81],... 

W. Bruckhoff, O. Geier, K. Hofbauer, G. Schmitt, D. Steinmetz. Rupture of a Sour Gas Line Due to Stress Oriented Hydrogen Induced Cracking - Failure Analyses, Experimental Results and Corrosion Prevention. NACE Corrosion/85, Paper 389, Boston, USA, 1985-03-25/29. 

B. D. Craig, T. V. Bruno, W. M. Buehler. Complexities of Failure Analyses in Sour Systems. Canadian Welding Society/American Society for Metals conference Materials and Welding for Sour Service and Low Temperature Service . Calgary, Alberta, Canada, 1997-11-20/21. 

Throughout the chapter, several examples will be provided that incorporate pneumatically actuated valves. It is important to note that the same functionality can be obtained with electric motor-actuated valves or electric solenoid-actuated valves. The selection of appropriate valves for a particular furnace and combustion process is a function of cost, performance, availability of clean instrument air, utility failure analyses, and personal preference. 

Engineers use statistical models to address quality control and reliability issues and to perform failure analyses. 

Bogdanovich AE. Multi-scale modelling, stress and failure analyses of 3-D woven composites. J Mater Sci 2006 41 6547-90. 

The ventilation system purpose described above, that of cleanliness, does not meet the criteria specified in DOE-STD-3009-94 to be identified as safety-significant. Ventilation failure analyses (Mitchell and Naegeli, 1999), summarized in Section 3.4, indicate that without the ventilation system operating, the expected dose to the public is negligible, and the contamination levels which would build up in normally occupied areas of the HCF are several orders of magnitude below that necessary to result in serious injury or death. Of course, normal operations could not continue to be accomplished with an inoperative ventilation system, in that contamination levels would eventually build up in occupied areas so as to result in worker doses which exceed SNL radiation protection administrative control limits and would be operationally unacceptable. Thus, the... 

Optimized preventive maintenance programmes can contribute to ensuring both safe and competitive NPPs. Reliability centered maintenance provides an optimization of preventive maintenance. The principles underlying reliability centred maintenance include preventing failures where the repercussions for the plant could be serious in terms of safety or economics. The methodology involves evaluation of the functional consequences of failure, analyses of experience feedback, and optimization of preventive maintenance tasks. Electricite de France (EdF) has implemented preventive maintenance programmes based on a reliability centred maintenance methodology at EdF nuclear plants, and results have shown benefits in safety, performance and cost. 

Laminate failure envelope analysis determines the combinations of selected load components that cause the failure of a laminate. Envelopes are constructed from the results of consecutive failure analyses, A computer code for creating failure envelopes is useful since the envelope in graphical form displays clearly the load-carrying capability of the laminate. Such a tool should allow the designer ... 

Load response and failure analyses of bars, beams, plates, shells, and mechanical and adhesively bonded Joints are common in structural design, as well as stability and free vibration analyses of bars, plates and shells. These analyses can always be performed with general purpose FE programs. Nevertheless, computer codes developed specifically for these analyses are useful because FE programs are laborious to use. These tools should have the following features ... 

Although not a true surface technique, SEM-EDS often provides useful information in regard to surface corrosion mechanism. The ubiquitous nature, low cost, and ease of use of this technique cause it to be used as a tool in many failure analyses involving corrosion. Because its analysis depth is much larger (approximately a micrometer) than the true surface techniques, it is not necesseiry to analyze samples that are high-vacuum compatible. This results in the necessity of almost no sample preparation for many different kinds of samples. 

The difficulties associated with recording corrosion information are many, ranging fi om the basic lack of details in failure analyses to the inherent complexity of the vari-ahles involved. The complexities associated with corrosion damage information are compounded by a general lack of standard schemes to represent materials in their operational environments. Data gathered in controlled laboratory environments can usually be obtained with more precision and for such data standards have been developed to stream-... 

The functional FMEA is used to evaluate failures in one or many subsystems that function within a larger system, while the hardware FMEA examines failures in the assemblies, subassemblies, and components within those subsystems. The FMEA, therefore, has great versatility in the system safety process. The analysis can either be specialized, without regard for other subsystems which are not within the scope of the analysis, or it can be generalized to encompass total subsystem or system effects of a given failure condition. However, because the FMEA does not consider the human factors element or multiple failure analyses within a system, other types of system safety analysis tools and techniques should also be utilized. 

Anandakumar G, Li N, Verma A, Singh P, Kim JH (2010) Thermal stress and probability of failure analyses of functionally graded solid oxide fuel cells. J Power Soiffces 195 6659-6670... 

The GDC 17 and GDC 18 of Appendix A to 10CFR5O requires that the on-site power systems including the batteries shall have sufficient capacity, independence, redundancy, and testability to perform their intended safety functions assuming a single failure. Spurious operations are supposed to be included in the failure analyses. 

---