The quality of production is defined by the actual deviations from the requirements stated in design and technological documentation including drawings. In this article the problem of ensuring steady decrease in quantity of deviations from these requirements by production is considered. Carrying out preventive actions, in combination with control of time and costs of correction of discrepancies of such decrease it is possible to achieve. For the solution of an objective the method of the modified FMEA using parameters and levels of ranging as elements of operation of technological process where at a design stage of a product are set structure, is offered and are adjusted on the basis of feedback of production and operation. Such statement of a problem demands automation of collecting and data processing which can be used for creation of the knowledge base necessary for management of productions. Considering the specification level used in this analysis it is also possible to obtain the data necessary for the solution of some other the problems, for example, connected with productions, including technologies, the…

Intermittence occurs randomly in time, place, amplitude and duration. The very nature of the failure mode suggests that the ability to detect and further isolate the intermittence root cause is based on detection SENSITIVITY and PROBABILITY rather than conventional methods concentrating on ohmic measurement accuracy. Simply put, you can’t detect an intermittent event until it occurs, and then you might have limited opportunities to catch it on the specific circuit when it does. Trying to measure fractions of a milliohm, scanning one circuit at a time, is ineffective for this particular failure mode. In this paper we will outline the problem of intermittence and its testing difficulties. More importantly, we will describe the unique equipment and process which has produced overwhelming success in Intermittence / NFF resolution and MTBF extension. Working with Total Quality Systems, (TQS) Ogden, Utah, we implemented our team-developed overhaul system called IFDIS (Intermittent Fault Detection and Isolation System) which incorporates all the necessary testing procedures and technological capabilities that are proving to be critical to the resolution of the chronic intermittent…

In this article, a framework for efficient strength analysis of large and complex automotive composite structures is presented. This article focuses on processes and methods that are compliant with common practice in the automotive industry. The proposed framework uses efficient shell models for identification of hot spots, automated remodelling and analysis of found hot spots with high-fidelity models and finally an automated way of post-processing the detailed models. The process is developed to allow verification of a large number of load cases in large models and still consider all potential failure modes. The process is focused on laminated composite primary structures. This article highlights the challenges and tools for setting up this framework.

This SAE Aerospace Information Report (AIR) is a compilation of engineering references and data useful to the technical community that can be used to ensure fuel system compatibility with composite structure. This AIR is not a complete detailed design guide and is not intended to satisfy all potential fuel system applications. Extensive research, design, and development are required for each individual application.

SAE JA6097 (“Using a System Reliability Model to Optimize Maintenance”) shows how to determine which maintenance to perform on a system when that system requires corrective maintenance to achieve the lowest long-term operating cost. While this document may focus on applications to Jet Engines and Aircraft, this methodology could be applied to nearly any type of system. However, it would be most effective for systems that are tightly integrated, where a failure in any part of the system causes the entire system to go off-line, and the process of accessing a failed component can require additional maintenance on other unrelated components.

This document provides recommended practices for the design, development, and verification testing of NWS systems.

Loss of power steering assist (LoA) is viewed as a potential hazard in certain vehicle operational scenarios. Despite the importance of this steering failure mode, few published test protocols for the objective or subjective evaluation of vehicle performance in a loss of assist situation exist.The first part of this paper examines five of the key steering failure modes that can result in LoA and discusses why LoA persists as a key industry challenge. The second part analyzes the situational dynamics affecting vehicle controllability during a LoA event and proposes a subjective evaluation driving course that facilitates evaluations in various LoA scenarios. A corresponding objective test procedure and metric is also proposed. These evaluation methods support consistent performance evaluation of physical vehicles while also enabling the prediction of vehicle characteristics early in the vehicle development process (VDP). The final section of this paper gives an overview of a steering system design method aimed at first classifying the level of risk associated with any LoA induced hazard (Automotive Safety Integrity Level - ASIL) and then taking appropriate…

The FE modeling guidelines and the design master S-N curve for weld root failure was recently proposed using the mesh-insensitive structural stress method. Due to increasing demands to validate the design master S-N curve, various weld root fatigue failure cases were reanalyzed based on well-documented weld root fatigue failure studies including different weld shapes and sizes, plate thickness combinations, and loading modes. Also, the validations of the master S-N curve for weld root failure were conducted using a well-documented structural joint fatigue data set as well as additional fatigue test results.Through the analyses, the proposed weld root failure modeling guidelines and the structural stress-based master S-N curve approach were confirmed to be good to use for practical applications to predict weld root failure.The critical weld size using the ratio of weld size and plate thickness for load carrying cruciform joints under tensile loading was re-evaluated. The structural stress method based critical crack size demonstrated the predictability of the failure mode (i.e., either toe failure or root failure) based on the relationship between weld size and…

Sandwich structures with honeycomb core are widely used in the lightweight design and impact energy absorption applications in automotive, sporting, and aerospace industries. Recently, the auxetic honeycombs with negative Poisson's ratio attract substantial attention for different engineering products. In this study, we implement Additive Manufacturing technology, experimental testing, and Finite Element Analysis (FEA) to design and investigate the mechanical behavior of a novel unit cell for sandwich structure core. The new core model contains the conventional and auxetic honeycomb cells beside each other to create a Hybrid Honeycomb (HHC) for the sandwich structure. The different designs of unit cells with the same volume fraction of 15% are 3D-printed using Fused Deposition Modeling technique, and the comparative study on the mechanical behavior of conventional honeycomb, auxetic honeycomb, and HHC structures is conducted. The quasi-static uniaxial compression tests are performed on the printed samples to investigate the mechanical behavior of the printed structures. The deformation and failure modes of the different designs are studied at the cell level utilizing FEA of the compression test and experimental observation.…

This study is a continuation of previous work assessing the robustness of a Cummins XPI common rail injection system operating with gasoline-like fuel. All the hardware from the original study was retained except for the high pressure pump head and check valves which were replaced due to cavitation damage. An additional 400 hour NATO cycle was run on the refurbished fuel system to achieve a total exposure time of 800 hours and detect any other significant failure modes. As in the initial investigation, fuel system parameters including pressures, temperatures and flow rates were logged on a test bench to monitor performance over time. Fuel and lubricant samples were taken every 50 hours to assess fuel consistency, metallic wear, and interaction between fuel and oil. High fidelity driving torque and flow measurements were made to compare overall system performance when operating with both diesel and light distillate fuel. Injector rate shapes were measured as a function of time, and high resolution x-ray imaging of the nozzle tips was performed as part of the final teardown analysis.…