Localized Necking of Sheet at Negative Minor Strains

Chan, K. S.; Koss, D. A.; Ghosh, A. K.

doi:10.1007/bf02645118

Cited by 72 publications

(20 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[31], for any loading condition, a definite initial angle of the groove giving the minimum limit strain of the left hand side exists. This conclusion was further confirmed by Chan et al [32] , Lian and Baudelet [33] . The conclusion above is widely used when calculating forming limit at present, i.e.…”

Section: Instability Theorysupporting

confidence: 79%

Forming limit of sheet metals based on mixed hardening model

Wang

Wan

2009

Sci. China Ser. E-Technol. Sci.

View full text Add to dashboard Cite

The calculation method of forming limit of sheet metals based on M-K instability theory is proposed, and the method is applicable to different yield criterions and hardening models. The forming limit diagrams of AA5754-O, AA6111-T4 aluminum alloy sheet and DP steel sheet under combined loading paths are obtained based on mixed hardening model with YLD2000-2D yield criterion proposed by Barlat in 2003 and L-C nonlinear kinematic hardening model proposed by Lemaitre and Chaboche. The results show that the forming limit diagram made up of limit strain (FLD-strain) is evidently influenced by the loading path. The forming limit diagram made up of limit stress (FLD-stress) is also influenced by loading path and it is not an only curve, which differs from the conventional view. The degree of the influence of loading path on FLD-stress is related with pre-strain. The larger the pre-strain is, the greater the influence of loading path on FLD-stress will be. The change of FLD-stress is small only when pre-strain is small. In addition, the hardening behavior of the material will influence the path-dependence of FLD-stress: The larger the proportion of kinematic hardening in the whole hardening is, namely the more obvious Bauschinger effect of the material, the greater the influence of loading path on FLD-stress will be. plastic forming of sheet metals, forming limit, hardening model, complex loading path

show abstract

Section: Instability Theorysupporting

confidence: 79%

Forming limit of sheet metals based on mixed hardening model

Wang

Wan

2009

Sci. China Ser. E-Technol. Sci.

View full text Add to dashboard Cite

show abstract

“…To describe the biaxial behavior of the material in region A, the quadratic Hill's yield function was used. Assuming normal anisotropy, for this yield criterion, the effective stress and effective strain for plane stress (σ 3 = 0) are given by [4]:…”

Section: Comparison Between Experimental and Theoretical Forming Limimentioning

confidence: 99%

“…Hill's theory, however, does not take into account the strain-hardening rate of the material or preexisting imperfections and cannot explain the phenomenon of localized necking under biaxial stretching conditions. After reexamination of Hill's theory, Chan et al [4] have suggested that under the strain states between uniaxial tension and plain strain, localized necking of sheet metal obeys a critical thickness strain criterion:…”

Section: Introductionmentioning

confidence: 99%

On the connection between microstructure and surface roughness of brass sheets and their formability

Stachowicz

2015

Acta Mech

View full text Add to dashboard Cite

The aim of this work was the analysis of the relationships between material properties and forming limits of a sheet, caused by the strain localization in the groove. In particular, we aim at the replacement of a nonmeasurable inhomogeneity coefficient of the material, the value of which has to be taken a priori, by measurable coefficients. In the proposed model, it is assumed that the material heterogeneity is a result of surface roughness and presence of internal defects (voids). The value of inhomogeneity coefficients changes with increasing strain. The experiments were carried out for M85 brass sheets, annealed to produce different microstructures. The measured values of some material parameters: strain-hardening constants n and C, normal anisotropy factors, inhomogeneity coefficients (surface roughness and volume fraction of voids) as well as forming limit curve demonstrated their dependence on the grain size. As a result of the experimental work, original equations were proposed, describing the relationship between inhomogeneity coefficients and effective strain and grain size. These equations were used in the theoretical calculation of the forming limit diagram. The theoretical calculations of the strain limits of the tested sheets were based on the associated flow rules, assuming strain-hardening and strain-softening process (Shima-Oyane equation and equations based on the Gurson theory). The analysis of the influence of different material parameters on the forming limit diagram has shown that in the case of the material tested, the value of limit strains depends decisively on the values of the inhomogeneity coefficients and grain size. The postulates showing proportional relationship between the value of a strain-hardening exponent and limit strains were not confirmed.

show abstract

“…Under uniaxial tension, Zircaloy-4 specimens tend to fail by shear across the width, unlike the through-thickness fracture that would occur during an RIA event. The onset of a localized necking instability has been analyzed by Chan and co-workers [11] such that necking will occur along slip bands at 40 o from the principal stress, which has been confirmed experimentally using the uniaxial RST specimen [4].…”

Section: Uniaxial Ring Stretch (Rst) Specimenmentioning

confidence: 99%

Mechanical Property Testing of Irradiated Zircaloy Cladding Under Reactor Transient Conditions

Daum

Majumda

Tsai

et al. 2002

Small Specimen Test Techniques: Fourth Volume

View full text Add to dashboard Cite

Specimen geometries have been developed to determine the mechanical properties of irradiated Zircaloy cladding subjected to the mechanical conditions and temperatures associated with reactivity-initiated accidents (RIA) and loss-of-coolant accidents (LOCA). Miniature ring-stretch specimens were designed to induce both uniaxial and plane-strain states of stress in the transverse (hoop) direction of the cladding. Also, longitudinal tube specimens were also designed to determine the constitutive properties in the axial direction.Finite-element analysis (FEA) and experimental parameters and results were closely coupled to optimize an accurate determination of the stress-strain response and to induce fracture behavior representative of accident conditions. To determine the constitutive properties, a procedure was utilized to transform measured values of load and displacement to a stress-strain response under complex loading states. Additionally, methods have been developed to measure true plastic strains in the gauge section and the initiation of failure using real-time data analysis software. Strain rates and heating conditions have been selected based on their relevance to the mechanical response and temperatures of the cladding during the accidents.

show abstract

Localized Necking of Sheet at Negative Minor Strains

Cited by 72 publications

References 15 publications

Forming limit of sheet metals based on mixed hardening model

Forming limit of sheet metals based on mixed hardening model

On the connection between microstructure and surface roughness of brass sheets and their formability

Mechanical Property Testing of Irradiated Zircaloy Cladding Under Reactor Transient Conditions

Contact Info

Product

Resources

About