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stress-to-craze value

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Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006944
EISBN: 978-1-62708-395-9
... when the applied tensile stress reaches a critical value temperature below T g , with a resulting brittle behavior. The presence of crazing in transparent polymers reflects the light due to a different refractive index, and thus it can be easily viewed at the correct angle. Traditional examples...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006934
EISBN: 978-1-62708-395-9
... of a craze. Source: Ref 42 The stress-intensity factor reaches a critical value, termed the critical stress-intensity factor, K Ic , at the fracture stress σ B . The value of K Ic defines the fracture toughness of the material: (Eq 14) K Ic = σ B ( π c ) 1 / 2...
Image
Published: 01 January 2002
Fig. 7 Isochronous plot of polycarbonate stress-strain behavior as a function of temperature. Note that the crazing locus decreases in strain value with increasing temperature. (a) 23 °C (73.5 °F). Relative humidity, 50%. (b) 40 °C (104 °F). (c) 80 °C (176 °F). (d) 100 °C (212 °F). Courtesy More
Image
Published: 15 May 2022
Fig. 8 Isochronous creep plot of polycarbonate stress–strain behavior as a function of temperature. Note that the crazing locus decreases in strain value with increasing temperature. (a) 23 °C (73.5 °F). Relative humidity, 50%. (b) 40 °C (104 °F). (c) 80 °C (176 °F). (d) 100 °C (212 °F More
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006926
EISBN: 978-1-62708-395-9
... on failure properties. After a plastic component is exposed to an organic chemical, aggressive molecules may diffuse into the component, leading to plasticization. Swelling of the material can result in high stresses that may cause crazing or cracking. Fracture has been observed in many glassy plastics...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006865
EISBN: 978-1-62708-395-9
... , glass transition temperature Fig. 8 Isochronous creep plot of polycarbonate stress–strain behavior as a function of temperature. Note that the crazing locus decreases in strain value with increasing temperature. (a) 23 °C (73.5 °F). Relative humidity, 50%. (b) 40 °C (104 °F). (c) 80 °C (176 °F...
Book Chapter

Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003541
EISBN: 978-1-62708-180-1
... stress-strain behavior as a function of temperature. Note that the crazing locus decreases in strain value with increasing temperature. (a) 23 °C (73.5 °F). Relative humidity, 50%. (b) 40 °C (104 °F). (c) 80 °C (176 °F). (d) 100 °C (212 °F). Courtesy Mobay Chemical Company Stress Cracking...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006940
EISBN: 978-1-62708-395-9
... for the compression half-cycle. This area remains almost constant for several cycles and then increases significantly ( Fig. 4 ). This effect is attributed to the production and growth of crazes after some induction period. For ABS, an increase of stress amplitude causes the energy to dissipate per half-cycle...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006918
EISBN: 978-1-62708-395-9
... . If fatigue loading is performed under constant stress-amplitude conditions and the geometric factor does not change within the limits of integration, then fatigue fracture is predicted to occur when the crack reaches a critical value, a c , that is directly linked to the fracture toughness. The number...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006909
EISBN: 978-1-62708-395-9
... deflection value for a given nominal surface stress. The standard deflection depends on the specimen thickness (e.g., 0.32 mm, or 0.013 in., for a specimen thickness of 10 mm, or 0.4 in., and a nominal surface stress of 1.80 MPa, or 0.26 ksi). ISO 75 applies to both neat resins (Part 2) and FRPs (Part 3...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006917
EISBN: 978-1-62708-395-9
... amorphous regions of the polymer, causing a reduction of these intermolecular forces and leading to molecular slippage and craze formation. Fig. 3 View of hydrogen bonding molecular interactions in a polyamide 6,6, resulting in attraction between neighboring molecules Environmental stress...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006910
EISBN: 978-1-62708-395-9
... to as crazing, in which the apparent crack is really a zone of fibrous material produced by the stress field ahead of the crack. This phenomenon can be present in glassy polymers as well as in semicrystalline materials, being related to microyielding to levels of several hundred percent strain. A similar...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.homegoods.c0090457
EISBN: 978-1-62708-222-8
... images, micro-FTIR in the ATR mode, and DSC/TGA/MFR analysis) showed no evidence of contamination or degradation from the molding process. The conclusion was that the parts failed via brittle fracture associated with stress overload. The stress overload was accompanied by severe apparent embrittlement...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006921
EISBN: 978-1-62708-395-9
... to be identical to that which occurs in air. The chemical environment accelerates the craze formation process by local plasticization, that is, enhancement of the local relative movement of molecular chains by reduced intermolecular interaction between chains. ESC can occur at much lower stresses and strains...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006932
EISBN: 978-1-62708-395-9
... of conductive metal filler into the polymer matrix ( Ref 8 ). Fig. 1 Residual stress distributions for various values of the Biot number, m , for the case that the initial temperature, T 0 , lies far above the glass transition temperature, T g . T ∝ , final temperature below T g ; L , sample...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006943
EISBN: 978-1-62708-395-9
... mechanism of fracture, such as crazing and shear tearing, and the various fracture modes of polymers, such as brittle and ductile behavior, fatigue, environmental stress cracking, creep, and others, are covered in the articles “ Crazing and Fracture in Polymers ,” “ Fracture Mechanics Testing of Plastics...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.power.c9001709
EISBN: 978-1-62708-229-7
... leading to rapid cooling. On evaporation of water, the surface would attain its normal temperature leading to relaxation of surface stresses. After a sufficient number of thermal cycles, a random or a crazed crack pattern appears on the surface. On repeated action, one or more of the surface fatigue...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006941
EISBN: 978-1-62708-395-9
... applied stress, σ 0 , results in a strain, ε 0 , that is directly proportional to stress and predictable according to ( Ref 2 – 5 ): (Eq 1) σ 0 = E ε 0 where the value E is the tensile modulus of elasticity for the material and is a constant. The dependence of strain...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006928
EISBN: 978-1-62708-395-9
... it is 0.10 ( Ref 7 ). If the strain is derived from the relative movement of the clamps rather than from an extensometer, the error in the calculated value of the tangent modulus at the origin can be 100% ( Ref 6 ). Yield Stresses Yield stresses of plastics depend on a variety of molecular mechanisms...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003522
EISBN: 978-1-62708-180-1
.... This was confirmed by microscopic examination, which showed the cracks to have been produced by stress-corrosion cracking of the material. While the specific cause of the stress-corrosion cracking was not investigated, it is suggested that there must have been a spillage of corrosive fluid on the bolt prior to heat...