Longer lasting components result from patented method of residual stress design for enhanced fatigue strength

Released on: September 24, 2007, 7:16 am

Press Release Author: Brian C. Murphy/Lambda Technologies

Industry: Aerospace

Press Release Summary: Lambda Technologies has been issued a U.S. patent for their
revolutionary method of designing beneficial, compressive residual stresses (RS)
into metallic components for
enhanced fatigue performance.

Press Release Body: Cincinnati, Ohio - September 24, 2007, - Lambda
Technologies has been issued a U.S. patent for their revolutionary method of
designing beneficial, compressive residual stresses (RS) into metallic components
for enhanced fatigue performance. This patented methodology will significantly
influence the implementation of compressive residual stresses in metallic components
used in many industries critical to the U.S. economy and its' national security such
as the aerospace, automotive, medical implants, and power generation markets. In the
absence of a proper residual stress design, surface enhancement processes can
produce little improvement in fatigue strength, high compensatory tensile stresses
and/or unacceptable distortion.

U.S. Patent No. 7,219,044 entitled "Method and System for Improving a Part's
Resistance to Stress Induced Failure" pertains to a detailed design protocol
developed to allow the compressive residual stress to be tailored for a given
component. The protocol comprises of a series of successive design steps that
ultimately allow the engineer to converge on a unique compressive residual stress
field for a given application.

At the outset, the performance criteria, failure mechanisms and operating conditions
of the component are assessed and a total stress state is determined from the sum of
the RS and applied stresses acting on the part during service. Traditional design
techniques do not take into account the existing RS imparted to the component during
manufacturing operations such as casting, forming, welding, heat treatment or
machining. Instead, existing design techniques generally assume that the component
is free of residual stress, which can lead to a significant error in the predicted
compressive residual stresses required. Lambda Technologies method accounts for any
manufacture related residual stresses. The method enables the designer to reliably
use compressive RS to offset the applied tensile stresses thereby reducing or
eliminating the effects of tensile RS within the part.

Next, using the patented fatigue design diagram (FDD), a customized compressive
field can be developed for a finite element model of the applied stresses to produce
a targeted high cycle fatigue performance given the mean and alternating applied
stresses, and the level of damage to be mitigated in different parts of the
component. Finite element analysis is used to predict the level of distortion and
compensatory tension. Finally, the customized compressive field is placed into the
component using the appropriate surface treatment such as Lambda Technologies
patented Low Plasticity Burnishing (LPB) process.

In its entirety, U.S. Patent No. 7,219,044 will not only impact the design of
components from a fatigue performance standpoint; moreover it will provide
tremendous cost savings to organizations that elect to adopt it into their design
standards. The methodology allows reduced use of
excess material, which is a common practice in traditional "over" design. This not
only provides a significant weight savings in the part but also serves to lower
production costs. Furthermore, Lambda Technologies method and system provides a
cost savings by enhancing component service life and making it no longer necessary
to maintain and replace parts as frequently, thereby reducing labor as well as
costly aircraft and machine downtime.

To discover how implementing Lambda Technologies patented fatigue design methodology
and testing protocol into your process will improve component performance, or to
download the Fatigue Design Diagram (FDD) Engineering Application Note, visit
www.lambdatechs.com and navigate to the "Discover LPB" web page.

Lambda Technologies is an innovative company incorporating a premier materials
research laboratory with a world-class engineering and production enterprise
dedicated to the development and optimization of surface treatments to improve
component performance. For additional information on Lambda Technologies or
licensing the LPB process, contact Lambda's Customer Service Department at (513)
561-0883 or visit www.lambdatechs.com.

###

Web Site:
http://www.lambdatechs.com/html/documents/LT_Press_Release_Fatigue_Design_Diagram_Sept_2007.pdf


Contact Details: Contact: Customer Service Department
Lambda Technologies Corporate Headquarters
3929 Virginia Avenue
Cincinnati, OH 45227-3411
Tel: (513) 561-0883
Toll-Free: (800) 883-0851
Fax: (513) 561-0886
E-mail: info@lambdatechs.com

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