Intellectual Property and Technology Licensing

Lambda's Patented Technologies

U.S. patents issued to Lambda Technologies

Method and System for Improving a Part's Resistance to Stress Induced Failure.

(Abstract) A method and system for designing a part with improved fatigue life and resistance to stress corrosion cracking in which residual stresses exisiting in the part are accounted for. The performance criteria and operating conditions of the part are assessed and a total stress state is determined from the sum of the residual stresses and applied stresses acting on the part. Unified Fatigue Performance Model or Smith-Topper-Neuber parameters are used to determine fatigue life functions which, in turn, are used in conjunction with a fatigue design diagram to determine the appropriate residual stress to introduce in order to optimize the part's resistance to stress induced failure mechanisms. A residual stress distribution is then designed to avoid distortion of the part while still imparting the beneficial effects of compressive residual stress.

Method for Improving the Magnitude of Compressive Stress Developed in the Surface of a Part.

(Abstract) This invention relates to a method and an apparatus for performing the method of inducing compressive residual stress along the surface of a part. In the preferred embodiment of the invention, the method includes burnishing or deep rolling a surface using a first and a second roller or ball burnishing members, whereby the first and second burnishing members may have a different diameter and/or modulus of elasticity. In another preferred embodiment of the invention, the burnishing operations may be performed while the surface of the part is at different temperatures.

Method and Apparatus for Providing a Layer of Compressive Residual Stress in the Surface of a Part.

(Abstract) The shot peening method and apparatus of the present invention utilizes control of the shot peening coverage to provide higher surface compression and comparable depth of compression to conventional 100% coverage peening but with reduced cold working providing improved thermal stability and reduction in shot peening time and cost. A preferred embodiment of this invention employs x-ray diffraction residual stress and percent cold work determinated by line broadening to establish the optimal degree of coverage for a given material and shot peening intensity.

Apparatus and Method for Forming Weld Joints having Compressive Residual Stress Patterns.

(Abstract) The welding apparatus and associated method are provided. The welding apparatus includes a welding tool for forming a weld joint along the surface of at least one workpiece. The welding apparatus also includes a compression tool for selectively inducing a layer of residual compressive stress in at least a portion of the surface of the weld joint and the surface of the at least one workpiece to thereby improve the material properties of the workpiece, including corrosion resistance and fatigue strength.

Method for Reducing Tensile Stress Zones in the Surface of a Part.

(Abstract) The present invention is a novel method for reducing tensile zones in the surface of a part comprising the steps of selecting a region of the part to be treated and programming a control unit of a burnishing apparatus to perform a burnishing operation, the burnishing operation being performed such that the density of burnishing and the magnitude of compression are varied to reduce the high tensile stress along the boundaries of the selected region. In a preferred embodiment of the invention the burnishing operation induces a deep layer of compression within the surface having associated cold working of less than about 5.0 percent.

Method and Apparatus for Providing a Residual Stress Distribution in the Surface of a Part.

(Abstract) The present invention is a novel method and an apparatus for implementing the method of inducing a layer of compressive residual stress along the surface of a part comprising the steps of selecting a region of the part to be treated; selecting the magnitude of compression and the residual stress distribution to be induced in the surface of the selected region of the part; exerting pressure against the surface of the selected region, the pressure being applied in a selected pattern along the surface to form zones of deformation having a deep layer of compressive stress; and varying the pressure being exerted against the surface to produce the desired residual stress distribution and magnitude of compression within the surface.

Burnishing Method and Apparatus for Providing a Layer of Compressive Residual Stress in the Surface of a Workpiece.

(Abstract) The burnishing method and apparatus for implementing the method of the present invention utilizes a single-point burnishing process to provide deep compression with a minimal amount of cold working and surface hardening. In particular, the area to be burnished along the surface of a workpiece is defined and a freely rotating burnishing ball is forced against the surface of the workpiece to produce a zone of deformation having a deep layer of compression within the surface. The burnishing ball is then rolled over the surface in a substantially nonoverlapping pattern. A preferred embodiment of the burnishing apparatus for implementing the burnishing method comprises a socket having a tip member incorporating a ball seat, a burnishing ball disposed within the ball seat, a rod member integrally formed with the tip member; and a socket support for supporting the socket on a conventional tool holder. The socket is provided with means for directing lubrication fluid from a reservoir to the ball seat to permit the burnishing ball to freely rotate and for directing a predetermined amount of lubrication fluid to the surface of the workpiece.

Automated System for Use in the Determination of Subsurface Material Properties by X-Ray Diffraction.

(Abstract) The present invention is directed to an automated system for use in the determination of subsurface material properties of a specimen by X-ray diffraction, comprising a specimen support, a rotatable mounting and aligning fixture for mounting the specimen support onto the shaft of a motor driven positioning system, a chemical holding tank having a first half section having a chemical holding chamber for providing a chemical bath for removing surface material from the specimen and a second half section for providing a position for permitting X-ray diffraction measurement of the specimen, a chemical reservoir in fluid communication with the chemical holding chamber of chemical holding tank to provide a steady supply of chemical solution to the chemical holding chamber through a closed loop system, a neutralization tank for receiving contaminated rinse water from the chemical holding tank, and an electronic controller for controlling the cycling of the specimen between the chemical holding chamber and the position for receiving a beam of X-rays from an X-ray source.