Preliminary slide This lecture is designed to be used to overview NDT methods in order to make students appreciate the capabilities of present day technology. The lecture is not meant to thoroughly present all of the details of these methods. A semester long course with hands-on laboratories can at best provide a detailed overview of the many different methods. Several methods require stand alone courses to fully present all of the aspects of these powerful methods.

Design for Inspectability A lecture developed by John C. Duke, Jr., Virginia Tech, with support from the ASNT Faculty Grant Program. ©2002

Learning Objectives 1.The student will be able describe the advantages of including NDT in the early stages of design. 2.The student will be able to describe how various decisions in the design process impact the inspection process.

A Typical Design Process Define Functional Requirements Formulate Initial Concept Assess wrt Service Requirements –Derive requirements for materials –Determine subcomponents Revise Initial Concept –Reassess wrt Service Requirements Refine materials selection Real or Virtual Prototype Trials Refine Concept Develop Manufacturing Process(es) Refine Concept & Manufacturing Begin Production

A Better Design Process Define Functional Requirements Formulate Initial Concept Assess wrt Service Requirements--- NDE Requirements –Derive requirements for materials –Determine subcomponents Revise Initial Concept –Reassess wrt Service Requirements Refine materials selection Real or Virtual Prototype Trials Refine Concept Develop Manufacturing Process(es)--- NDE Requirements Refine Concept & Manufacturing Begin Production

ASNT Handbook Series Beginning in 1982 ASNT has developed, and continues to update and expand a multiple volume Handbook series.

ASNT NDT Handbook Volumes [as of Fall 2002] Leak Testing Liquid Penetrant Testing Infrared and Thermal Testing Radiographic Testing Electromagnetic Testing Acoustic Emission Testing Magnetic Particle Testing Ultrasonic Testing Visual and Optical Testing Special NDT Methods

Many Designs Forget Inspection! Lack of access can make NDE impossible. NDE can often assist with process development In other instances minor design changes can significantly improve the reliability of NDE Expensive alternatives can overcome problems with lack of access, but a different design can often result in a product that is equally good but more economically inspected; a better design.

Need Access …got Computed Tomography? High resolution in difficult to access locations Courtesy of ARACOR

Airbus 300 Rudder attachment The attachment lug is readily inspectable when the rudder is apart from the plane

Not so when attached! The clevis attachment restricts access to this critical region. Could a different design eliminate this problem?

FRP Composite Bridge Beams

Are Alternatives to Steel I Beams

The Double Web I Beam restricts access to parts of the flanges… When the end is placed close to the wall of the abutment.

Post-Tension Tendons Post-tension tendons allow for construction of remarkable structures Post-tension tendons are embedded in concrete structures.

Inspecting for corrosion damage? Because the tendons are often buried within the structure and even the ends maybe inaccessible inspecting the tendons for possible corrosion is impossible in some locations. Tendon failure could be catastrophic.

Design for Inspectability? A possible design solution would be to incorporate a sensor with the tendon when it is installed. An optical fiber distributed strain sensor can be attached during construction.

Distributed Bragg Strain Sensor The strain at each sensor location can be measured.

Nozzles for Pressure Vessels Inspecting the welds that connect inlet, or outlet, piping to pressure vessels is complicated by the complex geometry that often involves curvature in two different directions.

An alternative design By altering the pressure vessel design the weld can be placed in a location that allows reliable inspection to occur much more easily. weld

Developing the Manufacturing Process(es) Many products are manufactured with multiple processing steps. Each step, presumably, adds value, while costing some amount. If inspection is only performed after all of the steps are completed, parts processes improperly at an early step result in excessive loss.

Using NDE to Monitor the Process(es) NDE, just during process development, can identify problems and make corrective action possible, immediately. Courtesy of Ultrasonic Arrays, Inc.

Summary Engineering design is a process that isn’t finished when the product is produced. It continues through in-service inspection, or inspection for fitness-for-service, or inspection for repair. The engineering design that accommodates inspection is a better design.