The high-rate brittle microplane concrete model: Part I: bounding curves and quasi-static fit to material property data

2012 ◽  
Vol 9 (4) ◽  
pp. 293-310 ◽  
Author(s):  
Mark D. Adley ◽  
Andreas O. Frank ◽  
Kent T. Danielson
2006 ◽  
Author(s):  
Per Bakke ◽  
Andreas Fischersworring-Bunk ◽  
Isabelle de Lima ◽  
Hans Lilholt ◽  
Ingemar Bertilsson ◽  
...  

Author(s):  
Robert M. Metcalf ◽  
Jessica Comstock ◽  
Brittany Coats

Abstract Computational models of infant head impact are limited by the paucity of infant cranial bone material property data, particularly with regards to the anisotropic relationships created by the trabecular fibers in infant bone. We previously reported high-rate material property data for human infant cranial bone tested perpendicular to trabeculae fiber orientation. In this study we measure the anisotropic properties of human infant cranial bone by analyzing bending modulus parallel to the trabeculae fibers. We tested human bone specimens from 9 donors ranging in age from 32 weeks gestational age to 10 months of age at strain rates 12.3-30.1 s^(-1). Bending modulus significantly increased with donor age (p=0.008), and was 13.4 times greater along the fiber direction compared to perpendicular to the fibers. Ultimate stress was greater by 5.1 times when tested parallel to the compared to perpendicular (p=0.067). Parietal bone had a higher modulus and ultimate stress compared to occipital bone, but this trend was not significant, as previously shown perpendicular to fiber orientation. Combined, these data suggest the pediatric skull is highly age-dependent, anisotropic, and regionally dependent. The incorporation of these characteristics in finite element models of infant head impact will be necessary to advance pediatric head injury research, and further our understanding of the mechanisms of head injury in children.


Author(s):  
Dan Jia ◽  
Yong-Yi Wang ◽  
Steve Rapp

Abstract Vintage pipelines, which in the context of this paper refer to pipelines built before approximately 1970, account for a large portion of the energy pipeline systems in North America. Integrity assessment of these pipelines can sometimes present challenges due to incomplete records and lack of material property data. When material properties for the welds of interest are not available, conservative estimates based on past experience are typically used for the unknown material property values. Such estimates can be overly conservative, potentially leading to unnecessary remedial actions. This paper is a summary of PRCI-funded work aimed at characterizing material properties and flaw characteristics of vintage girth welds. The data obtained in this work can be utilized to understand and predict the behavior of vintage pipelines, which is covered in a companion paper [1]. The material property data generated in this work include (i) pipe base metal tensile properties in both the hoop (transverse) and the longitudinal (axial) directions, (ii) deposited weld metal tensile properties, (iii) macrohardness traverses, (iv) microhardness maps, and (v) Charpy impact transition curves of specimens with notches in the heat-affected zone (HAZ) and weld centerline (WCL). These data provide essential information for tensile strength, strength mismatch, and impact toughness. In addition to the basic material property data, instrumented cross-weld tensile (ICWT) tests were conducted on CWT specimens with no flaws, natural flaws, and artificially machined planar flaws. The ICWT tests provide an indication of the welds’ stress and strain capacity without and with flaws. For welds with even-matching or over-matching weld strengths, the CWT specimens usually failed outside of the weld region, even for specimens with natural flaws reported by non-destructive examination. Having over-matching weld strength can compensate for the negative impact of weld flaws. All tested girth welds were inspected using radiography and/or phased array ultrasonic testing. The inspection results are compared with the flaws exposed through destructive testing. The ability of these inspection methods to detect and size flaws in vintage girth welds is evaluated.


Sign in / Sign up

Export Citation Format

Share Document