Engineering Applications of Residual Stress

ABSTRACT This paper describes three different optical systems designed to be used outside the lab for pipeline inspections. The first one is a robust and portable ESPI based hole-drilling unit with radial sensitivity used for residual stresses measurement. The device has a special diffractive optical element that produces an achromatic interferometer. The displacement component around […]

Residual Stresses Measurement and Inner Geometry Inspection of Pipelines by Optical Methods Part 2

Residual stresses measurement in a gas pipeline The optical residual stresses measurement system was used in a risky area of a gas pipeline located in a steep hill near to a small river. The soil moves constantly at that region. A contention structure was built in order to minimize soil movements and interactions between it […]

Contour Method Advanced Applications: Hoop Stresses in Cylinders and Discontinuities Part 1

ABSTRACT The traditional contour method measures a cross-sectional map of residual stress by cutting a body carefully in two and measuring the surface contour. This talk will present two new advances, both motivated by the measurement of a single challenging part. The first advance is a two-step process for measuring hoop stresses in cylinders. In […]

Contour Method Advanced Applications: Hoop Stresses in Cylinders and Discontinuities Part 2

RESULTS Bending moment stresses The bending moment stresses given by the analysis of Fig. 5 are shown in Fig. 8. The stresses varied nearly linearly from about -60 MPa on the inner surface to about 50 MPa on the outer surface. Fig. 8. Bending moment stresses calculated from the amount the cylinder sprung open (see […]

Measurement of Bulk Residual Stress Distributions in Thick-section Components using the Contour Method

ABSTRACT Residual stresses are known to play a significant role in many material failure processes (e.g., fatigue, fracture, and stress corrosion cracking). For example, pressure vessels typically contain welded joints. In many cases these welded joints are large (e.g., traveling around the entire circumference), contain significant amounts of residual stress, have reduced material properties, and […]

Application of a Finite Strain Elastic-Plastic Self-Consistent Model to Deformation of Magnesium

EXTENDED ABSTRACT Magnesium alloys are unique materials because tensile twinning and de-twinning can be easily activated, which leads to rapid texture and hardening evolution [1]. Here we present a study of the mechanical response of a magnesium alloy (AZ31) when deformed under twinning dominated conditions, i.e. uniaxial compression along prior extrusion axis. In-situ neutron diffraction […]

Probing Strained Semiconductor Structures with Nanoscale X-ray Diffraction

The tailoring of strain distributions within semiconductor features represents a key method to enhance performance in current and future generations of complementary metal-oxide semiconductor (CMOS) devices. Although the impact of strain on carrier mobility in semiconductor materials was first investigated over 50 years ago [1,2], its implementation within the inversion layer of the channels in […]

Residual Stress State in Tools Used for Thermo-mechanical Metal Forming Processes

ABSTRACT In thermo-mechanically coupled forming processes for industrial mass production residual stresses are an unavoidable consequence of the alternating inhomogeneous fields of temperature and mechanical stress developing in tools and components dependent on the process parameters applied. Hence, a considerable interest exists to get reliable information about origin and distribution of the relevant residual stress […]

Determining Residual Stress And Young’s Modulus – Can Digital Shearography Assist Part 1

Abstract Residual Stresses are inherent in most materials and structures which have been exposed to a machining or manufacturing process. They are known to have both a beneficial as well as detrimental influence on the performance of manufactured components and yet often go by undetected. This paper presents the results of a research project aimed […]

Determining Residual Stress And Young’s Modulus – Can Digital Shearography Assist Part 2

Results Three different types of materials namely mild steel, aluminium and brass, all supplied as 6 mm rolled flat bar, were chosen to manufacture the required cantilever samples. For each material three cantilevers were machined. One of the cantilevers was machined down to 4mm thickness by removing 2 mm of material from one side only. […]