What is Fracture: Definition and 72 Discussions

Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface of displacement, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially to the surface of displacement, it is called a shear crack, slip band, or dislocation.Brittle fractures occur with no apparent deformation before fracture; ductile fractures occur when visible deformation does occur before separation. Fracture strength or breaking strength is the stress when a specimen fails or fractures. A detailed understanding of how fracture occurs in materials may be assisted by the study of fracture mechanics.

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    Where do the units for fracture energy come from in this equation?

    I am having trouble understanding where the units to fracture energy come from when worked out with the following equation. 2\gamma_{ef}=\frac{K^{2}_{Ic}}{E} fracture energy = fracture toughness/young modulus i asked my teacher as this is part of my coursework but he was not able to...
  2. T

    Principal Stress and Strain on a Fracture

    Homework Statement Find the expressions for principal stresses in both plane strain and plane stress conditions sigma(x) = (K/(sqrt(2*pi*r)))*cos(theta/2)*(1-sin(theta/2)*sin(3*theta/2)) sigma(y) = (K/(sqrt(2*pi*r)))*cos(theta/2)*(1+sin(theta/2)*sin(3*theta/2)) T(xy) =...
  3. K

    True/False: Plate Size & Fracture Stress

    True or false: a large plate of a brittle material fractures at a higher applied tensile stress as compared to a small plate of the same material. and True or false: the critical stress for a fracture of an internal crack of length 1mm is less than the critical stress for fracture of the same...
  4. I

    Fracture and shear forces on a beam

    Homework Statement A 20.0 meter long uniform beam weighing 820 N rests on walls A and B, as shown in the figure a)Find the maximum weight of a person who can walk to the extreme end D without tipping the beam. b)Find the force that the wall A exert on the beam when the person is...
  5. I

    Static equilibirum, elasticity, fracture problem

    1. A 19.0 kg ball is supported from the ceiling by rope A. Rope B pulls downward and to the side on the ball. If the angle of A to the vertical is 22 degrees and if B makes an angle of 53 degrees to the vertical find the tension in rope A and then find the tension in rope B
  6. S

    Tension in three point loaded beam for Fracture calculation

    A beam with dimensions 10x10x50mm is loaded in it's middle with a load F and it's supported by two wedges at either end Given it's fracture toughness say 500MPa, what is the largest load that it can hold? I am assuming that the underside of the beam will go into Tension and to calculate...
  7. P

    How to Solve for Variables in Equations with Multiple Variables and Equations?

    \frac{1}{x^3(x^2+1)}=\frac{ax^2+bx+c}{x^3}+\frac{dx+e}{x^2}\\ ax^4+bx^3+cx^2+dx^4+ex^3=x^4(a+d)+x^3(b+e)+cx^2=1\\ c=0\\ b+e=0\\ a+d=0\\ i got 4 variables with 2 equations what to do??
  8. B

    What is the fracture strength?

    I am having difficult finding the meaning of the term 'fracture strength'. http://en.wikipedia.org/wiki/Flexural_strength" it means the flexural or bending strength but that is unsourced and marked as dubious. I was also wondering if it could be synonymous with fracture toughness or something...
  9. V

    Why Do Materials Like Polymers, Ceramics, and Metals Fracture Differently?

    what actually causes polymers, ceramics and metals to fracture in either of these ways? From what I understand, polymers can be either brittle or softer which has to do with whether they are thermoset or thermoplastic, saturated or unsaturated, long chain or short chain, etc. but what makes...
  10. P

    Determining Fracture Point for Materials: Quick Guide for Engineering Students

    Hi all, I'm a 1st year (first 2 weeks) engineering student, with a quick question in regards to fracture points of materials. We're currently going through the elastic modulus and the deflection formula, which is pretty handy and I think I've got a decent (basic) grasp on it now...
  11. S

    Can ABAQUS accurately predict fatigue life using crack propagation?

    I am curious if anyone here is familiar with ABAQUS and using it for crack propagation. I am doing a project on fatigue life and need to use a computer program (ABAQUS is our FEA) to predict fatigue life under specific loading conditions. I am planning to use crack propagation to do this and...
  12. B

    Energy required to fracture a planetary mass

    Energy required to "fracture" a planetary mass I was playing around with the Impact Effects calculator at http://www.lpl.arizona.edu/impacteffects/ and doing some thinking about the impact event scenario of the Moon's creation. The main bulk of the Earth seems to have stayed in one piece after...
  13. C

    Fracture mechanics versus Damage mechanics

    Hello, I was wondering if someone could clarify the major differences and limitations of Damage Mechanics and Fracture Mechanics. I'm more familiar with the fracture mechanics approach, but have never done any damage mechanics before. I'm just trying to sort out in my head how fracture...
  14. N

    Which action would prevent a fracture in the cyclist?

    Let's say a cyclist hits a tree and fractures his arm. Which of the following would have likely prevented the fracture: a) decrease in his velocity by factor of 2 b) decrease in his mass by factor of 2 What arguments can be used here to reason this (ex. momentum, energy, force)...
  15. U

    Fracture Mechanics - Crack Propagation and Stress Intensity Factors

    I am trying to determine the critical crack length of a part using finite element analysis. The software I am using (ABAQUS) has the ability to perform fracture analysis. I model the part, create a crack, and ABAQUS will output the stress intensity factors (modes I, II, and III) and contour...
  16. S

    Solving Nylon Rope Fracture Problem Up to 25 kg Lift Height

    Homework Statement A 25 kg object is being lifted by pulling on the ends of a 1.00 mm diameter nylon string that goes over two 3.10 m high poles that are 4.5 m apart, as shown in Figure 9-87. How high above the floor will the object be when the string breaks? *see attached picture* The...
  17. A

    Modeling Fracture: Intuition, Formula for Elastic Potential & Nodal Forces

    Hi, I've been looking into ways to model fracture in real-time and i ran into a few papers on the net, one was by a few people from MIT compsci lab that seemed to fit what i was trying to do very well. However some of the math in it is a bit involved. The link to the paper is, for instance...
  18. Astronuc

    Short Tutorial on Fracture Mechanics

    http://www.shodor.org/~jingersoll/weave4/tutorial/tutorial.html
  19. R

    Exploring Fracture Types in Metal: Fatigue and Creep

    types of fracture in metal
  20. K

    Fracture Toughness of Honeycomb Sandwich Panels

    I need to get the Fracture Toughness of Honeycomb Sandwich Panles of Aluminum & GFRP facings such that i want to get in the microscopic analysis with the help of SEM & TEM (Scanning Electron Microscope) (Transmission Electron Microscope)...what is the procedure of making specimen of honeycomb...
  21. P

    Bodies in Equilibrium, elasticity and fracture

    can anyone help me with this please...? :eek: How much pressure is needed to compress the volume of a steel block by 0.14 percent?
  22. T

    Hooke's Law and Stress Fracture

    Experience shows that for many materials Hooke's Law holds only over a very small range. A steel bar for instance can only be extended by about 1% by an applied force before it fractures. Translate into the microscopic picture this means that the distance between the molecules changes only by...
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