Modelling low velocity impact induced damage in composite laminates

The paper presents recent progress on modelling low velocity impact induced damage in fibre reinforced composite laminates. It is important to understand the mechanisms of barely visible impact damage (BVID) and how it affects structural performance. To reduce labour intensive testing, the development of finite element (FE) techniques for simulating impact damage becomes essential and recent effort by the composites research community is reviewed in this work. The FE predicted damage initiation and propagation can be validated by Non Destructive Techniques (NDT) that gives confidence to the developed numerical damage models. A reliable damage simulation can assist the design process to optimise laminate configurations, reduce weight and improve performance of components and structures used in aircraft construction

Modelling low velocity impact induced damage in composite laminates

The paper presents recent progress on modelling low velocity impact induced damage in fibre reinforced composite laminates. It is important to understand the mechanisms of barely visible impact damage (BVID) and how it affects structural performance. To reduce labour intensive testing, the development of finite element (FE) techniques for simulating impact damage becomes essential and recent effort by the composites research community is reviewed in this work. The FE predicted damage initiation and propagation can be validated by Non Destructive Techniques (NDT) that gives confidence to the developed numerical damage models. A reliable damage simulation can assist the design process to optimise laminate configurations, reduce weight and improve performance of components and structures used in aircraft construction

Fluid/thermal/chemical non-equilibrium simulation of hypersonic reentry vehicles

A multi-physics frame work has been setup for the simulation of surfaceheat flux for nonablating hypersonic reentry vehicles and presented in thispaper. The main goal of this work was to set up a simple approach for theheat flux prediction during the reentry of the vehicle. The vehicleconsidered in the calculation is an axisymmetric vehicle flying at zerodegree angle of attack. Chemical nonequilibrium in the flowfield is simulatedby implementing a set of finite rate equations in the laminar finite rate modelin FLUENT. The frame work set up was validated with the results availablein the literature. Good correlation was observed between the results fromthe commercial code with the implemented equations and the results fromthe literature

Transient Response of a Projectile in Gun Launch Simulation Using Lagrangian and Ale Methods

This paper describes the usefulness of Lagrangian and arbitrary Lagrangian/Eulerian (ALE) methods in simulating the gun launch dynamics of a generic artillery component subjected to launch simulation in an air gun test. Lagrangian and ALE methods are used to simulate the impact mitigation environment in which the kinetic energy of a projectile is absorbed by the crushing of aluminum honeycomb mitigator. In order to solve the problem due to high impact penetration, a new fluid structure coupling algorithm is developed and implemented in LS-DYNA, a three dimensional FEM code. The fluid structure coupling algorithm used in this paper combined with ALE formulation for the aluminum honeycomb mitigator allows to solve problems for which the contact algorithm in the Lagrangian calculation fails due to high mesh distortion. The numerical method used for the fluid and fluid structure coupling is discussed. A new coupling method is used in order to prevent mesh distortion. Issues related to the effectiveness of these methods in simulating a high degree of distortion of Aluminum honeycomb mitigator with the commonly used material models (metallic honeycomb and crushable foam) are discussed. Both computational methods lead to the same prediction for the deceleration of the test projectile and are able to simulate the behavior of the projectile. Good agreement between the test results and the predicted projectile response is achieved via the presented models and the methods employed

Temporal and geographical trends of incidence of thyroid cancer in Golestan, Iran, 2004-2013

Background: Thyroid cancer is the most common type of endocrine cancer. We aimed to determine the incidence rates of thyroid cancer across a 10-year period (2004-2013) in Golestan, Iran. Methods: We obtained the thyroid cancer data from Golestan Population-Based Cancer Registry (GPCR). Age-standardized incidence rates (ASR) were calculated and reported per 100 000 person-years. The Joinpoint software was used to assess time trends, and average annual percent changes (AAPCs) and their corresponding 95 confidence intervals (CIs) were reported. Results: Of 326 registered patients, 83 (25.5) were men and 243 (74.5) were women. The mean age was 51.3 and 42.6 years for males and females, respectively. Overall, the ASR of thyroid cancer was 2.2 per 100 000 person-year (AAPC = 2.76; 95 CI: -3.68 to 9.64). The test of co-incidence showed a statistically significant difference in the incidence of thyroid cancer between men (1.3) and women (3.2) (P < 0.001). According to our results, the ASR of thyroid cancer in western parts of Golestan is higher, including Gorgan and Aliabad cities. Conclusion: Increasing trends in incidence rates of thyroid cancer were found in the Golestan province during the study period, especially in women. We found significantly higher rates of thyroid cancer in women. Geographical diversities were seen in incidence rates of thyroid cancer in the Golestan province. Our results may be helpful for designing further researches to investigate the epidemiological aspects of thyroid cancer in the Golestan province. © 2021 Academy of Medical Sciences of I.R. Iran. All rights reserved

Satisfaction of Family Physicians (FPs) about the Effective Factors on Activation of FP Program and Rural Insurance in the Northern Provinces of Iran

BACKGROUND AND OBJECTIVE: Successful implementation of FP program and rural insurance requires continuous collaboration among the intersectoral and intrasectoral organizations. FPs’ satisfaction from related institutions can lead to more motivation, longer activity and better services in the organization. This study was performed to evaluate the level of FPs’ satisfaction in Northern provinces of Iran. METHODS: This cross-sectional study was performed in winter 2013. Totally 139 health centers from 552 which implement the family physician program and rural insurance coverage in Mazandaran, Golestan and Guilan provinces were randomly selected. In each center all of available FPs included. A researcher-made questionnaire was used for data gathering. In this questionnaire, personal characteristics with 10 open and closed questions, satisfaction from human and physical resources available at the first level, the function of health center of the city, the function of specialists at the second level, the performance of underlying population of intersectional organizations were asked through 34 questions with Likert scales. Validity and reliability of the questionnaire were approved. FINDINGS: Mean of the level of 188 FPs’ satisfaction about health team, equipment and facilities in the centers (of 5 score) was 3±0.6, underlying population was 2.8±0.8, intersectoral collaboration was 2.8±1, the function of district health center was 2.7±0.9, the function of specialists was 2.1±0.9. The level of FPs’ satisfaction from the specialists of the functional second level showed a significant difference in the Northern provinces of Iran (p=0.001). There was not a significant relationship between age, underlying population, recorded services, the number of replacements and the level of FPs satisfaction. CONCLUSION: The results of this study showed that the level of FPs’ satisfaction was moderate therefore, interventional program at different levels should be planned and implemented to protect and promote it