Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum.

Hydrogen embrittlement is a complex phenomenon, involving several length- and timescales, that affects a large class of metals. It can significantly reduce the ductility and load-bearing capacity and cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Despite a large research effort in attempting to understand the mechanisms of failure and in developing potential mitigating solutions, hydrogen embrittlement mechanisms are still not completely understood. There are controversial opinions in the literature regarding the underlying mechanisms and related experimental evidence supporting each of these theories. The aim of this paper is to provide a detailed review up to the current state of the art on the effect of hydrogen on the degradation of metals, with a particular focus on steels. Here, we describe the effect of hydrogen in steels from the atomistic to the continuum scale by reporting theoretical evidence supported by quantum calculation and modern experimental characterisation methods, macroscopic effects that influence the mechanical properties of steels and established damaging mechanisms for the embrittlement of steels. Furthermore, we give an insight into current approaches and new mitigation strategies used to design new steels resistant to hydrogen embrittlement.

Modified pre-curved patellar basket plate, reconstruction of the proper length and position of the patellar ligament--a biomechanical analysis.

Biomechanical properties of basket plate fixation for fracture dislocation in the distal part of the patella were studied on 22 fresh-frozen lower extremities (human cadaveric knees). The patella and the patellar ligament with the proximal tibia were removed. A comminuted fracture of the distal part of the patella was created with a chisel. The fractured patella, patellar ligament and tibial tuberosity of each specimen were fixed with a basket plate and mounted into the jaws of the testing machine. The measured load to failure was 421.66+/-45.90 N, which is approximately 70% higher than the results in other studies. The results of the measurements verified the results of finite element analysis. The modified precurved patellar basket plate developed in this study showed improved performance compared to the pre-existing fixation methods.