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NASA NTRS2004

Reliability Quantification of the Flexure: A Critical Stirling Convertor Component

Uncertainties in the manufacturing, fabrication process, material behavior, loads, and boundary conditions results in the variation of the stresses and strains induced in the flexures and its fatigue life. Past experience and the test data at material coupon levels revealed a significant amount of scatter of the fatigue life. Owing to these facts, the design of the flexure, using conventional approaches based on safety factor or traditional reliability based on similar equipment considerations does not provide a direct measure of reliability. Additionally, it may not be feasible to run actual long term fatigue tests due to cost and time constraints. Therefore it is difficult to ascertain material fatigue strength limit. The objective of the paper is to present a methodology and quantified results of numerical simulation for the reliability of flexures used in the Stirling convertor for their structural performance. The proposed approach is based on application of finite element analysis method in combination with the random fatigue limit model, which includes uncertainties in material fatigue life. Additionally, sensitivity of fatigue life reliability to the design variables is quantified and its use to develop guidelines to improve design, manufacturing, quality control and inspection design process is described.

Shah, Ashwin R.↗

NASA NTRS1995

Laser Opto-Electronic Correlator for Robotic Vision Automated Pattern Recognition

A compact laser opto-electronic correlator for pattern recognition has been designed, fabricated, and tested. Specifically it is a translation sensitivity adjustable compact optical correlator (TSACOC) utilizing convergent laser beams for the holographic filter. Its properties and performance, including the location of the correlation peak and the effects of lateral and longitudinal displacements for both filters and input images, are systematically analyzed based on the nonparaxial approximation for the reference beam. The theoretical analyses have been verified in experiments. In applying the TSACOC to important practical problems including fingerprint identification, we have found that the tolerance of the system to the input lateral displacement can be conveniently increased by changing a geometric factor of the system. The system can be compactly packaged using the miniature laser diode sources and can be used in space by the National Aeronautics and Space Administration (NASA) and ground commercial applications which include robotic vision, and industrial inspection of automated quality control operations. The personnel of Standard International will work closely with the Jet Propulsion Laboratory (JPL) to transfer the technology to the commercial market. Prototype systems will be fabricated to test the market and perfect the product. Large production will follow after successful results are achieved.

Laser Opto-Electronic↗

NASA NTRS1991

Software component quality evaluation

The paper describes a software inspection process that can be used to evaluate the quality of software components. Quality criteria, process application, independent testing of the process and proposed associated tool support are covered. Early results indicate that this technique is well suited for assessing software component quality in a standardized fashion. With automated machine assistance to facilitate both the evaluation and selection of software components, such a technique should promote effective reuse of software components.

Clough, A. J.↗

NASA NTRS2011

Data Interconnection Exploration

This project involves innovating the way the Quality Assurance organization at the Jet Propulsion Laboratory (JPL) tracks the receiving inspection of JPL Critical Items (JCI) procured from suppliers. The Quality Assurance organization uses a Microsoft Access based front-end to enter items into an inspection queue. The current design has grown to be much more than was expected when the inspection queue system was created in 2007. The goal is to migrate to a web based solution that will allow the handling of more data, multiple input interfaces, and customizable display options. This has been achieved by implementing a divided tables scheme, the use of ColdFusion programming language, and the usage of Web 2.0 technologies such as AJAX and jQuery. These updates will allow for future expansion as well as the standardization of inspection queues for the Quality Assurance organization. When engineers and scientists order flight hardware, they cannot use it straight away. After a spacecraft or a satellite has been launched, it will be impossible to repair; therefore, the parts used must be inspected to make sure they are operating correctly and within the required specifications. The task of inspecting these JPL Critical Items (JCI) falls on the Quality Assurance organization. One of the tools the receiving inspection group uses is a database to maintain a queue of inspections that need to be done and of inspections that have been completed. The current Access interface has worked well but increased amounts of data, multiple input interfaces, and changes to how data is handled have made it necessary to seek a new way of organizing items for inspection. In addition, the different inspection groups have recently been merged and each has different ways of keeping track of inspection information. The ultimate goal is for the new group to have one shared inspection queue and website. To achieve this goal, I have been working with Ian Luczon of Procurement Quality Assurance and 3 Myers Hawkins, another intern, to not only create the new queue for receiving inspection but also a central web portal for the newly combined inspection group.

flight hardware↗

NASA NTRS2015

Additive Manufacturing Infrared Inspection

The Additive Manufacturing Infrared Inspection Task started the development of a real-time dimensional inspection technique and digital quality record for the additive manufacturing process using infrared camera imaging and processing techniques. This project will benefit additive manufacturing by providing real-time inspection of internal geometry that is not currently possible and reduce the time and cost of additive manufactured parts with automated real-time dimensional inspections which deletes post-production inspections.

Gaddy, Darrell↗

NASA NTRS1972

Summary of nondestructive testing theory and practice

The ability to fabricate design critical and man-rated aerospace structures using materials near the limits of their capabilities requires a comprehensive and dependable assurance program. The quality assurance program must rely heavily on nondestructive testing methods for thorough inspection to assess properties and quality of hardware items. A survey of nondestructive testing methods is presented to provide space program managers, supervisors and engineers who are unfamiliar with this technical area with appropriate insight into the commonly accepted nondestructive testing methods available, their interrelationships, used, advantages and limitations. Primary emphasis is placed on the most common methods: liquid penetrant, magnetic particle, radiography, ultrasonics and eddy current. A number of the newer test techniques including thermal, acoustic emission, holography, microwaves, eddy-sonic and exo-electron emission, which are beginning to be used in applications of interest to NASA, are also discussed briefly.

Meister, R. P.↗

NASA NTRS2015

Method and Apparatus for Non-Destructive Evaluation of Materials

Methods and apparatus for characterizing composite materials for manufacturing quality assurance (QA), periodic inspection during the useful life, or for forensic analysis/material testing. System are provided that relate eddy-current sensor responses to the fiber layup of a composite structure, the presence of impact damage on a composite structure with or without a metal liner, volumetric stress within the composite, fiber tow density, and other NDE inspection requirements. Also provided are systems that determine electromagnetic material properties and material dimensions of composite materials from capacitive sensor inspection measurements. These properties are related to the presence of buried defects in non-conductive composite materials, moisture ingress, aging of the material due to service or environmental/thermal exposure, or changes in manufacturing quality.

Goldfine, Neil J.↗

NASA NTRS2017

Method and Apparatus for Non-Destructive Evaluation of Materials

Goldfine, Neil J.↗

NASA NTRS2003

Software for Managing Inventory of Flight Hardware

The Flight Hardware Support Request System (FHSRS) is a computer program that relieves engineers at Marshall Space Flight Center (MSFC) of most of the non-engineering administrative burden of managing an inventory of flight hardware. The FHSRS can also be adapted to perform similar functions for other organizations. The FHSRS affords a combination of capabilities, including those formerly provided by three separate programs in purchasing, inventorying, and inspecting hardware. The FHSRS provides a Web-based interface with a server computer that supports a relational database of inventory; electronic routing of requests and approvals; and electronic documentation from initial request through implementation of quality criteria, acquisition, receipt, inspection, storage, and final issue of flight materials and components. The database lists both hardware acquired for current projects and residual hardware from previous projects. The increased visibility of residual flight components provided by the FHSRS has dramatically improved the re-utilization of materials in lieu of new procurements, resulting in a cost savings of over $1.7 million. The FHSRS includes subprograms for manipulating the data in the database, informing of the status of a request or an item of hardware, and searching the database on any physical or other technical characteristic of a component or material. The software structure forces normalization of the data to facilitate inquiries and searches for which users have entered mixed or inconsistent values.

Salisbury, John↗

NASA NTRS1987

Automated inspection and precision grinding of spiral bevel gears

The results are presented of a four phase MM&T program to define, develop, and evaluate an improved inspection system for spiral bevel gears. The improved method utilizes a multi-axis coordinate measuring machine which maps the working flank of the tooth and compares it to nominal reference values stored in the machine's computer. A unique feature of the system is that corrective grinding machine settings can be automatically calculated and printed out when necessary to correct an errant tooth profile. This new method eliminates most of the subjective decision making involved in the present method, which compares contact patterns obtained when the gear set is run under light load in a rolling test machine. It produces a higher quality gear with significant inspection time and cost savings.

Frint, Harold↗

NASA NTRS1992

Enhanced automated spiral bevel gear inspection

Presented here are the results of a manufacturing and technology program to define, develop, and evaluate an enhanced inspection system for spiral bevel gears. The method uses a multi-axis coordinate measuring machine which maps the working surface of the tooth and compares it with nominal reference values stored in the machine's computer. The enhanced technique features a means for automatically calculating corrective grinding machine settings, involving both first and second order changes, to control the tooth profile to within specified tolerance limits. This enhanced method eliminates the subjective decision making involved in the tooth patterning method, still in use today, which compares contract patterns obtained when the gear is set to run under light load in a rolling test machine. It produces a higher quality gear with significant inspection time and cost savings.

Frint, Harold K.↗

NASA NTRS1976

Rationale for structural inspections

The methods developed to predict the reliability of aircraft structures depend upon inspection effectiveness which, in turn, depends upon structural complexity, quality, and the percentage of the structure inspected. Reliability can be enhanced by choosing materials properly, designing damage-tolerant structures, and increasing inspection frequency. And, for fleet operations, costs can be minimized through proper inspection schedules, and enhanced reliability can be compatible with minimum cost. The methods are derived from a combination of probability theory and engineering equations. A discussion of these methods is presented.

Davidson, J. R.↗

NASA NTRS1968

Nondestructive testing of brazed rocket engine components

Report details study made of nondestructive radiographic, ultrasonic, thermographic, and leak test methods used to inspect and evaluate the quality of the various brazed joints in liquid-propellant rocket engine components and assemblies. Descriptions of some of the unique equipment and methods developed are included.

Adams, C. J.↗

NASA NTRS1971

Ion and laser microprobes applied to the measurement of corrosion-produced hydrogen on a microscopic scale

An ion microprobe and a laser microprobe were used to measure concentrations of corrosion-produced hydrogen on a microscopic scale. Hydrogen concentrations of several thousand ppm were measured by both analytical techniques below the fracture surfaces of hot-salt stress-corroded titanium alloy specimens. This segregation of hydrogen below fracture surfaces supports a previously proposed theory that corrosion-produced hydrogen is responsible for hot-salt stress-corrosion embrittlement and cracking of titanium alloys. These advanced analytical techniques suggest great potential for many areas of stress-corrosion and hydrogen embrittlement research, quality control, and field inspection applications.

Gray, H. R.↗

NASA NTRS1972

Ion and laser microprobes applied to the measurement of corrosion produced hydrogen on a microscopic scale.

Use of an ion microprobe and a laser microprobe to measure concentrations of corrosion-produced hydrogen on a microscopic scale. Hydrogen concentrations of several thousand ppm were measured by both analytical techniques below corroded and fracture surfaces of hot salt stress corroded titanium alloy specimens. This extremely high concentration compares with only about 100 ppm hydrogen determined by standard vacuum fusion chemical analyses of bulk samples. Both the ion and laser microprobes were used to measure hydrogen concentration profiles in stepped intervals to substantial depths below the original corroded and fracture surfaces. For the ion microprobe, the area of local analysis was 22 microns in diameter and for the laser microprobe, the area of local analysis was about 300 microns in diameter. The segregation of hydrogen below fracture surfaces supports a previously proposed theory that corrosion-produced hydrogen is responsible for hot salt stress corrosion embrittlement and cracking of titanium alloys. These advanced analytical techniques suggest great potential for many areas of stress corrosion and hydrogen embrittlement research, quality control, and field inspection of corrosion problems. For example, it appears possible that a contour map of hydrogen distribution at notch roots and crack tips could be quantitatively determined. Such information would be useful in substantiating current theories of stress corrosion and hydrogen embrittlement.

Gray, H. R.↗

NASA NTRS1972

Military usage of connectors

Military specifications with general purpose parameters and termination data covering flat connectors and flat cables are proposed. The material, design, coating, and insulation are discussed, and drafts of specifications for flat cables including quality assurance provisions, and inspection are presented.

Schade, R.↗

NASA NTRS1987

Design, fabrication and delivery of a miniature Cassegrainian concentrator solar array system

The optical design of the miniature Cassegrainian concentrator (MCC) element was improved for both offpoint and onpoint power capability. The cell stack design has shown no losses under the high short term thermal stresses imposed by component level test and is projected to be capable of greater than five years thermal cycle life in low Earth orbit. The structural design met all requirements for stiffness and flatness and requires adjustable inserts for fine tuning of the GFRP structure to meet flatness goals. The completed, fully populated small and large MCC panels deliverable under this contract perform electrically as expected. A solid acceptance inspection program to guarantee quality of all purchased parts, and continued manufacturing process improvements will make the MCC design a viable low cost alternative to standard flat panel technology. Minor improvements to the cell stack design of the MCC element can make significant improvements in both the performance and manufacturability of the MCC system.

Kruer, Mark A.↗

NASA NTRS1993

Software Formal Inspections Guidebook

The Software Formal Inspections Guidebook is designed to support the inspection process of software developed by and for NASA. This document provides information on how to implement a recommended and proven method for conducting formal inspections of NASA software. This Guidebook is a companion document to NASA Standard 2202-93, Software Formal Inspections Standard, approved April 1993, which provides the rules, procedures, and specific requirements for conducting software formal inspections. Application of the Formal Inspections Standard is optional to NASA program or project management. In cases where program or project management decide to use the formal inspections method, this Guidebook provides additional information on how to establish and implement the process. The goal of the formal inspections process as documented in the above-mentioned Standard and this Guidebook is to provide a framework and model for an inspection process that will enable the detection and elimination of defects as early as possible in the software life cycle. An ancillary aspect of the formal inspection process incorporates the collection and analysis of inspection data to effect continual improvement in the inspection process and the quality of the software subjected to the process.

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