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strain-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
... below T g , the observed response will be brittle. The measured values of the glass transition depend on the molecular weight of the polymer and the strain-rate, which obviously influence the brittle behavior. Other parameters, such as molecular arrangement, govern the values of T g , (e.g., the type...
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
... how the applied stress, strain and/or strain rate, and temperature influence the rate of creep and stress relaxation and produce yielding. In addition, the effects of thermal and mechanical history must be considered. Polymers deform by two primary mechanisms: shear flow and crazing ( Ref 1...
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.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.a0006926
EISBN: 978-1-62708-395-9
... polymers, a value of χ < 0.5 leads to full solubility, while χ > 0.5 indicates partial solubility or swelling rather than dissolution. Partial solubility may arise either from limited compatibility or from the strain energy of a swollen network that resists further expansion ( Ref 28 , 29...
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
... a critical value of the plastic strain is reached. Therefore, polymer lifetime depends mainly on the rate by which plastic strain is accumulated ( Ref 31 ). Arbeiter et al. ( Ref 33 ) performed lifetime estimations using extrapolation concepts and accelerated testing methods. They showed that fracture...
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 Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006918
EISBN: 978-1-62708-395-9
... fracture mechanisms—such as crazing, cohesive-zone formation, fibrillation, blunted crack tearing, and sharp crack advance—that are found in polymers. The meaning of these polymer fracture mechanisms is conveyed through the following sections. Visual mechanistic images can reveal which analyses...
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
... a good understanding of the accumulative effects of service and environmental conditions on degradation and failure mechanisms. There are several ways to accelerate material degradation, including exposure to elevated temperature, pressure, or humidity; increasing stresses and strain levels (i.e...
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
... stress or strain for crazing or cracking to occur ( Ref 16 ). Because of this relationship, the effects of stress are relatively straightforward. The higher the level of tensile stress acting on a plastic component in conjunction with a particular chemical agent, the faster ESC failure will occur...
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
... resulting from a relatively high strain rate event and/or significant stress concentration. A relatively sharp corner formed by a retaining tab on the older design was shown to be a primary cause of the failures. Design Injection moldings Latches Stress concentration Polyacetal Brittle fracture...
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
.... At this transition temperature, there is competition between the ductile mode of failure (shear banding) and the brittle mode of failure (crazing) ( Ref 52 ). At a particular strain rate, then, polymers exhibit ductile behavior over a range of temperatures, T – T g , the breadth of which increases as the aging...
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.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
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.a0006943
EISBN: 978-1-62708-395-9
.... Note that values of the modulus of elasticity, E , or shear modulus, G , are temperature and strain-rate dependent. At high temperatures, the viscous flow plays an important role in manufacturing processes and also controls time-dependent behavior, for example, creep behavior. Therefore, fractography...
Series: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006919
EISBN: 978-1-62708-395-9
.... 8 Stress-strain curves for rubber-modified polycarbonate at room temperature as a function of strain rate Fig. 9 Load-displacement behavior of an impacted rubber-toughened polycarbonate box Fig. 10 Comparison of test values with predictions of the maximum load of an impacted...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003537
EISBN: 978-1-62708-180-1
... conditions develop first along the centerline and result in a flat fracture surface. With further increases in section thickness or crack size, the flat region spreads to the outside of the specimen, decreasing the widths of the shear lips. When the minimum value of plane-strain toughness ( K Ic...