1. Annealing point – It is the temperature at which n = 10.35P and internal stresses can be relieved
in about 15 mins.
2. Brittle fracture – Ceramics and glass undergo a fracture when subjected to a tensile test and
don’t undergo plastic deformation.
3. Chemically strengthened glass – when the silicate network in silica glass undergoes stress
periodically it produces strong glass.
4. Cold working – plastic deformation occurring well before one half times the melting point
5. Creep – can be defined as plastic deformation occurring at high temperature over constant load
and over a large period of time. The creep curve explains that plastic deformation occurs with
relation to time.
6. Critical Resolved sheer stress – when the tow value is big enough to cause a slip by dislocation
motion, then it is called that. (Applied force is needed to cause this deformation)
.
7. Critical shear stress – is one order of magnitude less than bulk shear modulus. Theoretical stress
level for shearing a crystal in the absence of dislocations.
8. Cross linking – joining of adjacent, linear polymeric molecules by chemical bonding.
9. Dislocation climb – a mechanism for creep deformation, in which the dislocation moves to an
adjacent slip plane by diffusion.
10. Ductility – Deformability
11. Dynamic modulus of elasticity – parameter representing the stiffness of a material under an
oscillating load.
12. Elastomer – a polymer with a rubbery plateau in the elasticity vs temperature graph
13. Engineering strain – increase in sample length under a load divided by sample length without
any stress
14. Engineering stress – load on a material divided by original sample area.
15. Flexural modulus – stiffness of a material as measured in bending.
16. Flexural strength – failure stress on a material as measured in bending.
17. Gage length – Region of minimum cross-sectional area in a mechanical test specimen.
18. Glass transition temperature – The temperature above which the glass becomes a supercooled
liquid and also a range below it where it is a rigid solid.
19. Griffith crack model - Prediction of stress intensification at the tip of a crack in a brittle material.
20. Hooke’s Law – is the linear relation between stress and strain during elastic deformation.
21. Lower yield point – the onset of plastic deformation in a low carbon steel
22. Melting range – temperature range at which the viscosity of glass is b/w 50 and 500 p.
23. Modulus of elasticity – slope of the stress strain curve in the elastic region
24. In bending – failure stress of a material as measured in bending
25. Modulus of rigidity – Elastic modulus under pure shear loading
26. Plastic deformation – permanent deformation associated with distortions and reformation of
atomic bonds through chemical bonding.
27. Poisson’s ratio – Mechanical Property indicating the contraction perpendicular to extension
caused by tensile stress.
28. Relaxation time – the time taken for the stress on a polymer to go below the initial applied
stress
29. Residual stress – the stress remaining with a structural material after all the applied loads are
removed.
30. Resolved shear stress – stress operating on a slip system.
31. Rockwell hardness – common mechanical parameter
32. Shear Modulus – Elastic modulus under pure shear loading
33. Shear strain – elastic displacement caused by pure shear loading.
34. Shear stress – load per unit area
35. Slip system – a combination of families of crystallographic planes and directions that correspond
to dislocation motion
36. Softening point - Temperature at which glass has a viscosity of 10^7 P, corresponding to the
lower end of the working point
37. Softening temperatures – the temp at which the material in a heat expansion experiment can no
longer support the weight of length monitoring probe
38. Solution hardening – Fortification of a material associated with restriction of plastic deformation
due to solid solution formation
39. Specific strength – strength per unit density
40. Strain hardening – the strengthening of a metal alloy by deformation
41. Strain hardening exponent – the slop of a log -log true stress vs true strain plot between plastic
deformation and the onset of necking
42. Stress relaxation – mechanical phenomena where stress reduces exponentially with time under
a constant strain
43. Tempered glass – heat treatment that serves to place the exterior surface in a residual
compressive state
44. Tensile strength – the maximum stress experienced by a material during a tensile test
45. Toughness = total area under stress strain curve, upper yield point – distinct break from the
elastic region in the stress strain curve for a low carbon steel
46. Upper yield point – mechanical behavior involving both solid like and fluid like behavior
47. Working range – temp range at which glass products are formed 10^4-8
48. Slope of stress strain curve in the elastic region – young’s modulus.
Formula sheet