Ductile/brittle Fracture Ductile materials are materials which displays large numbers of plastic deformation, while brittle materials show little or no plastic deformation before fracture. The diagram is the a tensile stress-strain curve, which represents the degree of plastic deformation exhibited by both brittle and ductile materials before fracture. Crack initiation and propagation are vital to fracture. The manner in which the crack propagates through the material gives great insight into the mode of fracture. In ductile material ( ductile fracture), the crack moves slowly and is assisted by large amount of plastic deformation.
The plastic settlement cracks occur due to the settlement of heavy aggregates at bottom and water at top surface or due to concrete’s tendency to reduce its volume and a restraint in the reduction by either reinforcement or duct will cause adjacent concrete to settle and form crack over the restraining area. In exposed situations, this may increase the risk of corrosion of the reinforcement and pose a threat to durability of the structure. Cracks may develop further due to subsequent drying shrinkage, leading to possible cracking through the full depth of the concrete
This causes the mass to deflect; the deflection is sensed by a suitable means and is converted into an equivalent electrical signal. B. Types of Accelerometer Sensors There are different types of accelerometers. Mechanical ones have something like a mass attached to a spring suspended inside an outer casing. When it is subjected to linear acceleration, the casing moves off immediately leaving behind the mass and spring stretches with a force that corresponds to the acceleration.
Frequent debonding failures Since composites are often constructed of different ply layers into a laminate structure, they can "delaminate" between layers where they are weaker.Delamination and cracks in composites are mostly internal and hence require complicated inspection techniques for detection. Composite to metal joining Metals expand and contract more on variations in temperature as compared to composites. This may cause an imbalance at joinery and may lead to
This rare earth element is ductile because it has the ability to deform under tension. It is also malleable because it is able to be permanently pressed out of shape without cracking. Ytterbium has a Vickers Hardness of 0.206 gigapascals and a Brinell Hardness of 0.343 gigapascals
CHAPTER 8 MISCELLANEOUS TOPICS ________________________________________ 8.1 INTRODUCTION 8.1.1 Destructive Destructive testing, tests are carried out to the specimen's failure, in order to understand a specimen's structural performance or material performance under dissimilar loads. These tests are usually much easier to carry out, yield more information, and are easier to interpret than nondestructive testing. Destructive testing is most suitable, and economic, for objects which will be mass-produced, as the cost of destroying a small number of specimens is negligible. It is
Water is one of the most efficient quenching media where maximum hardness is required, but it is liable to cause distortion and cracking of the work piece. Where hardness can be sacrificed, whale, cotton seed and mineral oils are used. These tend to oxidize and form sludge with consequent lowering of efficiency. The quenching velocity of oil is much less than water. To minimize distortion, long cylindrical objects should be quenched vertically, flat sections edgeways and thick sections should enter the bath first.
These construction failure mainly created by the resonance. So engineers have to identify the natural frequency of a construction and they have to build the construction without resonance. They use shock mounts to absorb resonance and vanish absorbed energy, so the construction will be safe. So they can decrease the damage of construction by earthquakes. In road construction, vibrating rollers are used to compact the surface.
Since the forces and the deformations generally are quite complex. It is usually useful to use simplifying assumptions to obtain a traceable solution. As the strain involved in plastic deformation process is very large, it is usually possible to neglect elastic strain and consider only the plastic strain (rigid-plastic region). The strain hardening is also neglected. The principal use of study of metal working process is for determining the forces required to produce given deformation for geometry prescribed by the process and is the ability to make prediction of the stress, strain, and velocity at every point in the deformed region of the billet.