Modeling the Thermo-Structural Response of Railcar Floor Assemblies During Standard Fire Resistance Tests

2018 ◽  
Author(s):  
Christian Rippe ◽  
Anil Kapahi ◽  
Brian Lattimer
Keyword(s):  
Shear Fracture ◽  
Structural Response ◽  
Sandwich Composite ◽  
Temperature Dependent ◽  
Endurance Test ◽  
Minute Exposure ◽  
The Core ◽  
Fire Endurance ◽  
Endurance Tests ◽  
Failure Models

Performing fire endurance tests of railcar floor assemblies in accordance with NFPA 130 is expensive given the minimum size requirements of 3.7 m (12 ft) in length and the full vehicle width. Often it is not financially viable to conduct such tests on several iterations of designs for the purpose of design optimization. Simulations of the fire endurance tests can be performed in place of experiments to provide predictions of floor assembly response of multiple designs at much lower cost. However, capturing the thermo-structural response of the floor assembly requires the ability to model the relevant physical phenomena including softening and weakening of the steel frame, degradation of the fire insulation, and failure of the composite floor. A methodology for performing such simulations was developed under this research addressing each of these phenomena. Temperature dependent thermal and mechanical properties of all modeled materials captures material softening and weakening. Degradation of the insulation was handled through a novel temperature dependent shrinkage approach. Failure models for the sandwich composite floor panels were obtained from literature to predict shear fracture of the core based on a maximum principal shear stress approach and delamination of the core/facesheet based on a maximum strain energy approach. The developed methodology was applied to the simulation of a fire endurance test of an exemplar railcar floor assembly using the commercial finite element solver Abaqus. The assembly was known to hold a passing rating for a 30-minute fire endurance test according to NFPA 130. The floor assembly consisted of a stainless-steel frame, fiberglass insulation, and a ply-metal composite floor. Sequentially coupled thermal and structural models were developed to predict the thermostructural response of the floor assembly for a 30-minute exposure to the ASTM E119 prescriptive fire curve. User-subroutines were utilized to implement the sandwich composite failure models developed for predicted core shear fracture and core/facesheet delamination. The predicted temperature rise on the unexposed surface of the floor assembly after a 30-minute exposure ranged from 50°C to 90°C. The floor assembly was also predicted to maintain structural integrity with the applied crush load, having a center-point vertical deflection of 161 mm after the 30-minute exposure. This resulted in a predicted pass rating for a 30-minute exposure which agrees with the floor assembly’s actual fire rating.

Damage behavior of potting materials in sandwich composites with pinned joints

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Cesim Atas ◽  
Alper Basmaci
Keyword(s):  
Core Material ◽  
Sandwich Composite ◽  
Composite Panels ◽  
Sandwich Composites ◽  
Resin Infusion ◽  
Damage Behavior ◽  
Mechanical Joints ◽  
The Core ◽  
Bottom Face ◽  
Infusion Technique

AbstractThe damage behavior of the potting materials around a pinhole, being used in the mechanical joints of sandwich composites, is investigated experimentally. The sandwich composite panels used in the tests were manufactured by the vacuum-assisted resin infusion technique. Each of the top and bottom face sheets of the panels consisted of two woven E-glass/epoxy layers. As the core material, PVC foam (AIREX

Structural Response of Fiber Composite Fan Blades

1975 ◽  
Author(s):  
C. C. Chamis ◽  
M. D. Minich
Keyword(s):  
Quantitative Data ◽  
Fiber Composite ◽  
Structural Response ◽  
Aerodynamic Heating ◽  
Analysis Method ◽  
Centrifugal Forces ◽  
The Core ◽  
Composite Mechanics ◽  
Composite Blades ◽  
Load Conditions

A fiber composite airfoil, typical for high-tip speed compressor applications, is subjected to load conditions anticipated to be encountered in such applications, and its structural response is theoretically investigated. The analysis method used consists of composite mechanics embedded in pre- and post-processors and coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, centrifugal, and combinations of these. The various responses investigated include root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. Also, the core-shell concept for composite blades is an inefficient design (core plies not highly stressed) and appears to be sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for such an analysis, and to provide quantitative data of the various responses which can be helpful in designing such composite blades.

scholarly journals Correlation between Core Strength and Stability with Body Mass Index among Postmenopausal Women.

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
S Bhosale Komal ◽  
V Bhosale Siddhi ◽  
Anandh Dr. S
Keyword(s):  
Body Mass Index ◽  
Postmenopausal Women ◽  
Body Mass ◽  
Pearson Correlation ◽  
The Body ◽  
P Value ◽  
Endurance Test ◽  
Core Strength ◽  
The Core ◽  
Flexion Test

Women in postmenopausal period of their life face various physical and physiological changes causing lack of estrogen and progesterone hormones, changes in the reproductive and genitals organs, vasomotor system in the body along with mood related symptoms such as anxiety, etc. Lifestyle, body fat distribution and anthropometric changes adds on to the bone strength in postmenopausal women. It may be a risk factor for osteoporotic fracture, cardiovascular, metabolic diseases, etc. Core strength and stability is greatly influenced by body composition and adiposity. The aim of the study was to correlate the core strength assessed with the Body Mass Index (BMI) among postmenopausal women. The objective of the study is to find the correlation between the core strength assessed with the Body Mass Index using 60° flexion test, Beiring Sorenson test and Unilateral Hip Bridge Endurance test among postmenopausal women with age ranging from 46-70 years. 96 healthy postmenopausal women in Karad city with a natural history of menopause were selected for the study. Based upon BMI values, the subjects were grouped as Underweight (<18.5 kg/m2), Normal weight (18.5-24.9 kg/m2), Overweight (25-29.9 kg/m2 and more). The outcome values for strength were correlated with the BMI of postmenopausal women. In the study, the Pearson correlation(r) was -0.361 and the P value was 0.0003 showing extremely significant correlation between the BMI and 60° Flexion test. For the Beiring Sorenson Test, the Pearson correlation value was -0.305 and the P value was 0.0025 showing very significant correlation between the BMI and Beiring Sorenson Test. Correlation of BMI and Unilateral Hip Bridge Endurance Test shows a Pearson Correlation value of -0.322 and the P value 0.0013 claiming very significant correlation between the BMI and Unilateral Hip Bridge Endurance Test. The study concludes that there is a significantly negative correlation between the core strength and stability with the Body Mass Index among postmenopausal women.

Study on Sandwich Core Modeling for Structural Analysis of Sandwich Composite Structure

2018 ◽  
Vol 926 ◽  
pp. 57-63
Author(s):  
Hyun Bum Park
Keyword(s):  
Structural Analysis ◽  
Composite Structure ◽  
Solid Modeling ◽  
Modeling Method ◽  
Core Structure ◽  
Sandwich Composite ◽  
Damage Area ◽  
The Core ◽  
Sandwich Core ◽  
Sandwich Composite Structure

This study aims to investigate numerically the damage area of a sandwich composite structure. In this work, the optimal sandwich core modeling method was proposed. This study applied two modeling methods to compare their analysis results for the structural analysis of the sandwich composite structure. Firstly, the modeling of sandwich core structure was performed with laminate modeling method. Secondly, the modeling of core structure was performed with core solid modeling method. The laminate modeling method was compared with the core solid modeling method. For the modeling, a carbon/epoxy composite structure was applied to the face sheet. And a nomex honeycomb core was applied to the core. Finally, comparing the result of modeling as actual shape with the one of virtually applying the thickness and modeling, it was examined that the former had three times more stress than the latter.

An individually adjusted endurance test reveals differences in physical fitness between young and old Beagles

2021 ◽  
Vol 49 (03) ◽  
pp. 165-172
Author(s):  
Maray Willen ◽  
Malin Lorke ◽  
Patrick Wefstaedt ◽  
Karin Lucas ◽  
Ingo Nolte
Keyword(s):  
Heart Rate ◽  
Physical Fitness ◽  
Individual Performance ◽  
Carbon Dioxide Partial Pressure ◽  
Ground Reaction Forces ◽  
Endurance Test ◽  
Endurance Tests ◽  
Reaction Forces ◽  
Performance Development ◽  
The Individual

Abstract Objective Aim was to establish an individually adapted endurance test for dogs on a treadmill, which takes the individual‘s physical condition into account. To check the applicability of the test, two age groups of clinically healthy beagles were examined. Methods A total of 10 clinically healthy Beagles were enrolled and divided in a younger (1–3 years, n = 5) and older group (> 8 years, n = 5). The individual comfort gait speed of each dog was determined on a treadmill with integrated force plates. A maximal time of 20 minutes at trot was set for the endurance test. The test was terminated prematurely if the dog showed signs of fatigue (massive panting, unwillingness to move further). Blood samples were taken at general examination (G), prior to (B) and post exercise (P) for determination of lactate level (LL), oxygen and carbon dioxide partial pressure (pO2, pCO2), bicarbonate (HCO3 –), base excess (BE) and pH. On each occasion (G, B, P) heart rate (HR) and respiratory rate (RR) were recorded. Additionally, vertical ground reaction forces (Fz) were analysed. Results The older dogs (age: 10.4 ± 0.89 years) completed the test with less speed and duration compared to the younger dogs (age: 2.4 ± 0.89 years), which managed to complete the maximum time. Lactate levels in the older dogs were higher than in the younger dogs at all timepoints of examination. Contrary to the younger dogs, there was no significant increase in the heart rate of the older dogs. Ground reaction forces were not significantly different between the groups. Conclusion and clinical relevance Whereas standardised endurance tests allow for the comparison of fitness levels between dogs, an individually adjusted endurance test aims at objectively determining the physical fitness of the single dog taking into account its individual performance. Such a test allows to examine the individual performance development over time and to evaluate medicinal therapies or dietary measures, e. g. in aging dogs. HR, RR, LL, blood gases (pCO2, pO2) and acid-base metabolism (HCO3 –, BE, pH) were found to be appropriate parameters for determining the physical capacity of the dogs during endurance tests as these parameters change under physical stress and are indicative for the onset of fatigue.

Frequency- and Temperature-Dependent Ferromagnetic Resonance of Co/CoO Core-Shell Nanoparticles

2004 ◽  
Vol 818 ◽  
Author(s):  
U. Wiedwald ◽  
J. Lindner ◽  
M. Spasova ◽  
Z. Frait ◽  
M. Hilgendorff ◽  
...  
Keyword(s):  
Ferromagnetic Resonance ◽  
Resonance Field ◽  
Core Shell ◽  
Direct Measure ◽  
Temperature Dependent ◽  
Spin Magnetic Moment ◽  
Shell Nanoparticles ◽  
The Core ◽  
G Value ◽  
Core Shell Nanoparticles

AbstractFerromagnetic Resonance experiments are used to investigate the magnetic properties of monodisperse Co/CoO core-shell nanoparticles with diameters of about 10nm. From frequency- dependent measurements at various frequencies of 9-80 GHz the g-value is determined to be 2.13 which suggests an fcc bulk-like environment of the Co atoms within the core of the particles. This result yields a direct measure of the ratio of orbital to spin magnetic moment νL/νS=0.065. Moreover, from temperature-dependent measurements of the resonance field the anisotropy energy is extracted and found much lower than the hcp bulk value.

Temperature-Dependent Vibration of Various Types of Sandwich Beams with Porous FGM Layers

2020 ◽  
pp. 2150016
Author(s):  
Mohsen Rahmani ◽  
Sajjad Dehghanpour
Keyword(s):  
Thermal Stresses ◽  
Equations Of Motion ◽  
Functionally Graded ◽  
Geometrical Parameters ◽  
Type I ◽  
Sandwich Beams ◽  
Temperature Dependent ◽  
The Core ◽  
Graded Layers ◽  
Lagrange Strain

By using a high order sandwich beams theory which is modified by considering the transverse flexibility of the core, free vibration characteristics of two models of sandwich beams are studied in this paper. In type-I, functionally graded layers coat a homogeneous core, and in type-II, an FG core is covered by homogeneous face sheets. To increase the accuracy of the model of the FGM properties, even and uneven porosity distributions are applied, and all materials are considered temperature-dependent. Nonlinear Lagrange strain and thermal stresses of the face sheets and in-plane strain of the core are considered. To obtain the governing equations of motion, Hamilton’s principle is used and a Galerkin method is used to solve them for simply supported and clamped boundary conditions. To verify the results of this study, they are compared with the results of literatures. Also, the effect of variation of temperature, some geometrical parameters and porosities on the frequency are studied.

Propulsive efficiency and structural response of a sandwich composite propeller

2019 ◽  
Vol 84 ◽  
pp. 250-258 ◽  
Author(s):  
Xuting Zhang ◽  
Yi Hong ◽  
Fan Yang ◽  
Zhonghai Xu ◽  
Jianguang Zhang ◽  
...  
Keyword(s):  
Structural Response ◽  
Sandwich Composite ◽  
Propulsive Efficiency

The influence of different types of core materials on the impact behaviour of sandwich composites

2018 ◽  
pp. 78-83
Author(s):  
Cihan Kaboglu
Keyword(s):  
Sandwich Structures ◽  
Core Material ◽  
Sandwich Composite ◽  
Balsa Wood ◽  
Impact Behaviour ◽  
The Core ◽  
Glass Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
The Impact ◽  
Core Materials

Sandwich structures are popular in applications in which the weight of the component affects the efficiency, especially in the aviation and aerospace industries. This study aims to understand the impact behaviour of sandwich structures with different core materials. Sandwich structures are manufactured with glass fibre reinforced polymer skins and balsa wood, polyethylene terephthalate (PET) and polyvinyl chloride (PVC) core through resin infusion under flexible tools. Three different core materials were tested and compared using the damaged area of the back face of the sample. The effect of the core materials on the mechanical behaviour of the structures is crucial. The results showed that the microstructure of the core materials plays an important role, because althoughthe density of balsa wood is greater than the density of PET and PVC, the structures having PVC and PET as core materials undergo less damage than those having balsa wood as a core material. Keywords: Sandwich composite, impact behaviour, core materials.

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