Stress fracture of the capitate reports A 42-year-old male physical exercise teacher presented to his general practitioner (GP) with a 4-month history of bilateral wrist pain. He was unable to recall any specific episode of trauma, but the nature of his work as a gymnastics teacher required repeated dorsiflexion of both wrists. The pain was enough to keep him awake at night and he had developed...

Stress fractures are rarely an indication for surgical treatment. In our case we decided to operate on the patient because of distraction of the fragments. Solid bony healing took longer than in traumatic fractures, but the good functional result confirmed our regimen.

Low-velocity plate impact experiments using a single-stage gas-gun are performed on Zr58.5Cu15.6Ni12.8Al10.3Nb2.8. Compressive fracture surfaces of the samples subjected to varying impact velocities and stress amplitudes are evaluated in order to study their loading rate dependence. Samples impacted at increasing loading rates, from increasing velocities of impact, show a larger extent of local...

The in-plane (plane stress) fracture toughness of two polyester (PET, PETG) sheets were assessed using the essential work of fracture (EWF) method after thermal and hygrothermal aging performed just below glass temperature. This ensured that physical aging takes place. On the aged sheets the yield stress (σy), enthalpy relaxation (ΔH) and EWF parameters were determined. It was observed that the...

Fracture toughness resistance curves describe a material's resistance against crack propagation. These curves are often used to characterize biomaterials like bone, nacre or dentin as these materials commonly exhibit a pronounced increase in fracture toughness with crack extension due to co-acting mechanisms such as crack bridging, crack deflection and microcracking. The knowledge of appropriat...

We propose a new method to investigate stress homogeneity along plate boundaries based on the cumulative misfit of individual fault plane solutions, calculated using assumed stress tensors. Using this method, some segments of faults can be defined, without the time-consuming inversions for stress directions from earthquake fault plane solutions. We assume that the misfits are relatively constan...

A model function relating effective stress to fracture permeability is developed from Hooke's law, implemented in the tensorial form of Darcy's law, and used to evaluate discharge rates and pressure distributions at regional scales. The model takes into account elastic and statistical fracture parameters, and is able to simulate real stress-dependent permeabilities from laboratory to field stud...

Stress fracture of the femoral neck is a rare complication of total knee arthroplasty. We report a case of femoral neck fracture following revision arthroplasty of the ipsilateral knee. Contributing factors may have been the patient's osteoporosis and a period of immobilisation before the revision arthroplasty. The patient was treated successfully with hemiarthroplasty of the hip. In patients w...

Observations of natural fractures in core or image logs typically give limited information on orientation, aperture and intensity. Because of the sparseness of wellbore intersections of fractures, data analysis results in incomplete statistical characterization of the fracture population, leaving interwell characterization almost impossible. Using basic fracture mechanics models and a novel cor...

The dynamic fracture behavior of layered architectures is experimentally studied. Specifically, crack penetration, trapping, and branching at an interface are examined. A newly introduced optical technique called Digital Gradient Sensing (DGS) that quantifies elasto-optic effects due to a non-uniform state of stress is extended to perform full-field measurements during the fracture event using ...