Bond-Breaking Relaxation Governs Onset of the Fracture Instability
نویسنده
چکیده
A dynamic crack will travel in a straight path up to a material-dependent critical speed beyond which its path becomes erratic. Predicting this critical speed and discovering the origin of this instability are two outstanding problems in fracture mechanics. We recently discovered a simple scaling model based on an effective elastic modulus that gives successful predictions for this critical speed. We now show that a simple atomic picture based on broken-bond relaxation at the dynamic crack tip provides an explanation for the origin of the effective elastic modulus.
منابع مشابه
Ab initio dynamics of rapid fracture∗
As our title implies, we consider materials failure at the fundamental level of atomic bond breaking and motion. Using computational molecular dynamics, scalable parallel computers and visualization, we are studying the failure of notched solids under tension using in excess of 108 atoms. In rapid brittle fracture, two of the most intriguing features are the roughening of a crack’s surface with...
متن کاملMolecular View on Supramolecular Chain and Association Dynamics.
The chain and association dynamics of supramolecular polymer ensembles decisively determines their properties. Using neutron spin echo (NSE) spectroscopy we present molecular insight into the space and time evolution of this dynamics. Studying a well characterized ensemble of linearly associating telechelic poly(ethylene glycol) melts carrying triple H-bonding end groups, we show that H-bond br...
متن کاملStress-dependent molecular pathways of silica–water reaction
Stress-corrosion of silica by water is studied by exploring the stress-dependent potential energy surface computed quantum mechanically at the level of molecular orbital theory. An ordered silica nanorod with clearly defined nominal tensile stress is constructed to model a structural unit of the stressed crack tip. Three competing hydrolysis reaction pathways are determined, each involving a di...
متن کاملEffect of Priming Dose of Atracurium on the Onset of Muscle Relaxation: A Controlled Clinical Trial
ABSTRACT The aim of this study was comparison of priming and intubating dose of Atracurium on the onset of muscle relaxation time to testing an alternative method for urgent operation. one hundred, 20-30 years old men that were condidate for urgency surgery entered in this study and divided in two groups randomly. First group was relaxed with Priming dose of Atracurium. In this way, %5 mg (pr...
متن کاملWatching Hydrogen Bonds Break: A Transient Absorption Study of Water.
Ultrafast infrared transient absorption measurements of the complete hydroxyl OD stretching mode spectrum of HOD in water, from 100 fs to tens of picoseconds, observe hydrogen bond breaking and monitor the equilibration of the hydrogen bond network in water. In addition, the vibrational lifetime, the time constant for hydrogen bond breaking, and the rate of orientational relaxation are determin...
متن کامل