Delamination is a common failure mechanism in ultra-high molecular weight polyethylene (UHMWPE) tibial inserts [Wright and Rimmnac, 1988]. Changes in polyethylene mechanical properties, such as subsurface embrittlement due to oxidation, may promote crack propagation. The assessment of through-thickness properties may, therefore, provide insight into delamination mechanisms. Using the small punc...

A fracture mechanics model is developed for the initiation and propagation of a crack through a porous ice layer of finite thickness under gravitational overburden. It is found that surface cracks generated in response to a tidally induced stress field may penetrate through the entire outer brittle layer if a subsurface ocean is present on Europa. Such penetration is found to be very unlikely i...

Abstract. Improved Giant MagnetoResistance Magnetometers (IGMRM) offers many advantages for subsurface cracks detection. This paper presents new detection opportunity of fatigue cracks close to fasteners or rivets with an improved rotating head. The latter was developed around an IGMRM and a well design electromagnetic flux focuser. The capabilities of the system for the one to the third alumin...

A turbine blade root contains notches that locate into a “fir-tree” root fixing in the turbine disc. Fatigue initiation in these stress concentrating features is of some concern. When a turbine blade is cast, the primary orientation along the blade is controlled (usually in the <001> direction) to within certain limits, however the secondary orientation (i.e. the orientation of any notches) is ...

The effect of low cycle fatigue (LCF) predamage on the subsequent very high cycle fatigue (VHCF) behavior is investigated in TC21 titanium alloy. LCF predamage is applied under 1.8% strain amplitude up to various fractions of the expected life and subsequent VHCF properties are determined using ultrasonic fatigue tests. Results show that 5% of predamage insignificantly affects the VHCF limit du...

An analysis of inner cone cracks in brittle solids subject to cyclic indentation in liquid is presented. These inner cone cracks, so named because they form well within the maximum contact circle, are postulated to be driven by a hydraulic pumping mechanism. Unlike their more traditional outer cone crack counterparts, inner cones do not appear in monotonic loading or even cyclic loading in the ...

We describe a Matlab-based, interactive, selfcontained, graphics-oriented code to process shearwave splitting data from microearthquakes in order to image the fractured subsurface in geothermal reservoirs. The code consists of three main modules: 1) data processing, 2) forward modeling, and 3) inverse modeling. The first module allows for rapid and precise measurement of fast S-wave polarizatio...

Usually ultrasonic techniques tend to evaluate the closed cracks as smaller than the actual size. In this paper, we describe two strategic techniques for accurately evaluating the closed cracks by means of ultrasound. First, we show the advanced technique utilizing the thermal stress induced by cooling a cracked part. It is shown that a small amount of temperature decrease is effective to open ...