Experimental investigation on adhesive bonding of similar and dissimilar weld joint used for automotive applications

The automobile industry has started using adhesive bonding to join load bearing components which aerospace industry has been using for decades. Adhesive lap joints are used frequently in the manufacture of automobile. In present study, structural adhesives were used to join the aluminium alloy (AA5083 H111) with the HSS dual phase (DP780) steel. Adhesive bonding appears to be one of the appropriate methods of joining dissimilar materials. The aim of this work is to analyze the tensile strength of similar and dissimilar joints. The influence of various parameters was also investigated such as the overlap length and the bondline thickness of specimens. In DP steel, there is 22% increase in strength for similar lap joint when overlap length changes from 10 mm to 15 mm, while there is 45% increase in strength when it varies from 15 mm to 20 mm. Similarly in case of Al alloy, there is 26% increased strength for similar lap joints when length varies from 10 mm to 15 mm, while it increased to 42% when length changes from 15 mm to 25 mm and there is about 35% increase in strength for length varies from 20 mm to 25 mm. In case of dissimilar joints, firstly there is about 16% increase in strength then there is 5% decrease while after that there is 45% increase in strength. Adhesion failure, cohesion failure and mixed failure were obtained experimentally during failure mode analysis. As the strength of joint increases, failure mode shows a transition from adhesion failure to cohesion failure. From the literature survey it is evident that limited work has been carried out on analysis of shear-tensile strength of adhesively bonded steel and aluminium joint with variation in bonding parameters. Not much work on failure mode analysis of bonded joints during tensile testing has been reported. In present work a noval attempt has been made to analyze the shear-tensile strength and failure mode of adhesively bonded steel and aluminium joint with variation in bonding parameters.

Micro versus Macro Shear Bond Strength Testing of Dentin-Composite Interface Using Chisel and Wireloop Loading Techniques

Shear bond strength (SBS) testing is a commonly used method for evaluating different dental adhesive systems. Failure mode analysis provides valuable information for better interpretation of bond strength results. The aim of this study was to evaluate the influence of specimen dimension and loading technique on shear bond strength and failure mode results. Eighty macro and micro flowable composite cylindrical specimens of 1.8 and 0.8 mm diameter, respectively, and 1.5 mm length were bonded to dentinal substrate. Four study groups were created (n = 20): Macroshear wireloop, Gp1; Microshear wireloop, Gp2; Macroshear chisel, Gp3; and Microshear chisel, Gp4. They were tested for SBS using chisel and wireloop loading devices followed by failure mode analysis using digital microscopy and SEM. Two- and one-way ANOVA were used to compare stress at failure values of different groups while the Kruskal–Wallis test was used to compare between failure modes of the tested groups. Gp4 recorded the highest mean stress at failure 54.1 ± 14.1 MPa, and the highest percentage of adhesive failure in relation to the other groups. Specimen dimension and loading technique are important parameters influencing the results of shear bond strength. Micro-sized specimens and chisel loading are recommended for shear testing.

Reliability and Availability Study of a Gas Turbine based on usual Approaches with a Failure Mode Analysis

The rotating machines like gas turbine types are highly valuable in the gas transportation industry. They are often strategic and have a major impact on the proper operation of gas transport and compression facilities. In this context, the aim of this work is to increase efficiency and production by developing an approach for this kind of installations using real data collected from the operation of the gas turbine. The objective is to provide a database relating to the reliability, availability, and maintenance of gas turbines while using standard reliability approaches. In addition, ensuring maximum availability of this type of rotating machine by preventing its failures and reducing emissions, and by minimizing start-up sequences, which reduces emissions when starting this machine. Also, the proper operation of these gas turbine installations with the reliability approaches developed in this work makes it possible to model the effects of failures in order to predict optimal operating performance and increase the life of their components. This, therefore, ensures a reliable and safe operation of the gas turbine in a compression station for economically profitable gas recovery.

Failure Mode and Effect Analysis for a Programmable Logic Controller-Based Control Unit for a Miniature Neutron Source Reactor Pneumatic Transfer System

The Pneumatic Transfer System (PTS) is an auxiliary system of Ghana Research Reactor-1 (GHARR-1) used to transfer the sample capsule in and out of the reactor irradiation sites. The PTS′ controller unit design and construction was carried out because the original transfer system was not designed to operate in Cyclic Neutron Activation Analysis (CNAA). To address these situations, a Programmable Logic Controller (PLC) has been used to design and construct a control unit to facilitate a CNAA application for GHARR-1. The design has been simulated successfully using LOGO! Soft Comfort software, version 8. A Failure Mode and Effect Analysis (FMEA) was conducted on the PTS Control Unit (PTSCU) to evaluate and document, by item failure mode analysis, the potential impact of each functional or hardware failure of the control unit, personnel and system safety, system performance, maintainability, and maintenance requirements. Each potential failure is ranked by the severity of its effect so that appropriate corrective actions can be taken to eliminate or control the high-risk items. The result obtained upon the analysis shows that the likelihood of occurrence of failures, detection, and severity on the control unit is low per the risk priority number. The paper outlines the severity classification and description used in FMEA, the likelihood of detecting various failures of components, and failure causes and effect.