Earthquake Load Reduction Effects of Boiler Structures by High Energy Absorbing Seismic Ties

2014 ◽  
Author(s):  
Kiyoshi Aida ◽  
Kodai Kawate ◽  
Yuichi Hiyoshi ◽  
Kotaro Kawamura ◽  
Satoshi Fujita
Keyword(s):  
Energy Absorption ◽  
Shear Force ◽  
Seismic Waves ◽  
Time History ◽  
High Energy ◽  
Lumped Mass ◽  
Support Structure ◽  
Reduction Effect ◽  
Energy Absorbing ◽  
The Relationship

Seismic ties are steel energy absorbing devices installed between the boiler and its support structure. This paper deals with the relationship between the energy absorption of a new type of seismic tie (made of low yield strength steel and with an optimized I-sectional shape) and its reduction effect on the resultant shear force of the support structure. To quantify the relationship between the energy absorption and the reduction effect on the resultant shear force, time-history analyses using a lumped mass vibration model that simulates the boiler structure, were performed for three representative design seismic waves (The largest class (level 2) waves of Taft, El Centro and Hachinohe earthquakes). The time-history analysis results demonstrated that the energy absorption increasing rates of the new seismic ties were correlated quantitatively with the shear force reduction rates of the support structure for the three design seismic waves.

Composite Core Cross Tube Crushing Analysis

2020 ◽  
Author(s):  
Sean Jenson ◽  
Muhammad Ali ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Deformation Mode ◽  
High Energy ◽  
Absorption Capacity ◽  
Functionally Graded ◽  
Layer By Layer ◽  
Thin Walled ◽  
The Cross ◽  
Energy Absorbing

Abstract Thin walled axial members are typically used in automobiles’ side and front chassis to improve crashworthiness of vehicles. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of inclusion of functionally graded cellular structures in thin walled members under axial compressive loading. A compact functionally graded composite cellular core was introduced inside a cross tube with side length and wall thickness of 25.4 mm and 3.048 mm, respectively. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were evaluated. The results showed that the inclusion of composite graded cellular structure increased the energy absorption capacity of the cross tube significantly. The composite graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the cross tube thus delaying local tube wall collapse and promoting large localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that were observed in the empty cross tube under axial compressive loading. The variation in deformation mode resulted in enhanced stiffness of the composite structure, and therefore, high energy absorption by the structure. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.

Design of Fiber-Reinforced Composite Tubes as Energy Absorption Element

2009 ◽  
Author(s):  
Y. Yang ◽  
S. Terada ◽  
M. Okano ◽  
A. Nakai ◽  
H. Hamada
Keyword(s):  
Energy Absorption ◽  
High Energy ◽  
Fiber Reinforced ◽  
Inertia Moment ◽  
Reinforced Composite ◽  
Bending Behavior ◽  
High Energy Absorption ◽  
Energy Absorbing ◽  
Frp Tubes ◽  
Two Sides

As an energy absorption member, fiber-reinforced composites (FRPs) are more favorable because they are light in weight and possess better energy absorption capabilities as compared to their metal counterparts. However, the energy absorbing mechanisms of FRP are complicated owning to the multi-micro fractures. Therefore, in this study, the designs of FRP tubes were carried out with considerations directed at the energy absorbing mechanisms. Two methods based on the design of the energy absorbed by bending of the fronds (Ubend) and the energy absorbed by fiber fractures (Uff) are concentrated. Here the bending behavior of frond can be considered as the bending beam by an external force. And it is found that Ubend is affected directly by the inertia moment I, which is affect by the geometry. Therefore, FRP tubes were fabricated to have a geometry combined with a bigger I. Additional, in order to get more fiber fractures to get an increased Uff, the design of bending stress, σ, was carried out. FRP tubes bending towards one side only rather than two sides are proposed to get bending fronds with a double thicker thickness, which in turn led to high stresses, many fiber fractures and high energy absorption.

Development of High Energy Absorbing Seismic Tie With I-Sectional Shape for Thermal Power Boiler Structure

2013 ◽  
Author(s):  
Kiyoshi Aida ◽  
Kotaro Kawamura
Keyword(s):  
Thermal Power ◽  
Reaction Force ◽  
High Energy ◽  
Scale Model ◽  
Design Parameters ◽  
Load Testing ◽  
Support Structure ◽  
Flange Thickness ◽  
Round Section ◽  
Energy Absorbing

This paper deals with new types of steel seismic ties, which are energy absorbing devices installed between boiler and its support structure. To enhance the aseismic reliability of the boiler and its support structure, energy absorbing capacities of the seismic ties must be increased. To increase the capacities, sectional shapes of the seismic ties have been optimally designed. Concretely, I-section seismic ties as new types have been gained by optimizing the design parameters, material (conventional carbon steel and low yield strength steel), sectional height, web thickness, flange thickness under conditions to maximize absorbing energy and to restrict the reaction force equal to or smaller than that of round-section current seismic tie. As a result of cyclic load testing using 1/3 scale model, it was verified that energy absorption of the new types of seismic ties were 16–23 % larger than that of the current seismic tie.

An Assessment of the Impact Performance of Bonded Joints for Use in High Energy Absorbing Structures

1985 ◽  
Vol 199 (2) ◽  
pp. 121-131 ◽  
Author(s):  
J A Harris ◽  
R D Adams
Keyword(s):  
Energy Absorption ◽  
Joint Strength ◽  
High Energy ◽  
Lap Joints ◽  
Impact Performance ◽  
Single Lap Joints ◽  
Epoxy Adhesives ◽  
Energy Absorbing ◽  
The Impact ◽  
Spot Welded

Using an instrumented impact test, the strength and energy absorption of bonded single lap joints have been measured for single lap joints with four epoxy adhesives and three aluminium alloy adherends. Compared with the static values, joint strength is not significantly affected by the high loading rates. Energy absorption is large when joint strength is sufficient for plastic deformation to occur in the adherends prior to failure, which is only the case for certain adherend/adhesive combinations. Spot welded joints are shown to be inferior in performance in the tests. The effect of loading rate on bonded joint strength has been analysed using a non-linear finite element method, from which predictions of joint strength in keeping with the experimental results have been obtained. Crush tests carried out on open-ended cylinders have been used to simulate the impact behaviour of an energy absorbing structure. Similar performance was observed for cylinders with either bonded or spot welded longitudinal seams, although the large deformations in the crumple zones led to some debonding and weld fracture.

scholarly journals Effect of Fiber Mat Density and Crushing Mechanism on the Energy Absorption Capacity of GFRP Crashworthy Tubes

2019 ◽  
Vol 8 (9S3) ◽  
pp. 297-301 ◽  
Keyword(s):  
Energy Absorption ◽  
Deformation Mechanism ◽  
Theoretical Calculations ◽  
Peak Load ◽  
High Energy ◽  
Constant Load ◽  
Absorption Capacity ◽  
Energy Absorption Capacity ◽  
High Energy Absorption ◽  
Energy Absorbing

The aim of this study is to examine the effect of fiber mat’s density and deformation mechanism of tubes with and without die compression. In this study a new mode of deformation mechanism of density graded GFRP circular tube is examined when they are subjected to axial compression on to a die and without die to examine its energy absorbing capacity. Theoretical calculations were made to predict the crushing stress of different specimens. It is observed that increasing density of fiber increases energy absorption value but decreases the specific energy absorption and the die could trigger progressive crushing additionally decreasing peak load. Here the compressed tube wall is compelled to be deformed towards the end of compression die with a little range of bending curvature which was forced by the radius of the die at high crushing stress and the major part of the deformation takes place at a nearly constant load, which leads to high energy absorption capacity. Comparison between theoretical prediction values by derived equations and the experimental results shows good correlation.

Negative stiffness honeycombs for recoverable shock isolation

2015 ◽  
Vol 21 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Dixon M Correa ◽  
Timothy Klatt ◽  
Sergio Cortes ◽  
Michael Haberman ◽  
Desiderio Kovar ◽  
...  
Keyword(s):  
Energy Absorption ◽  
High Energy ◽  
Negative Stiffness ◽  
Static Displacement ◽  
Content Type ◽  
Beam Geometry ◽  
Displacement Behavior ◽  
Shock Isolation ◽  
Energy Absorbing ◽  
Force Displacement

Purpose – The purpose of this paper is to study the behavior of negative stiffness beams when arranged in a honeycomb configuration and to compare the energy absorption capacity of these negative stiffness honeycombs with regular honeycombs of equivalent relative densities. Design/methodology/approach – A negative stiffness honeycomb is fabricated in nylon 11 using selective laser sintering. Its force-displacement behavior is simulated with finite element analysis and experimentally evaluated under quasi-static displacement loading. Similarly, a hexagonal honeycomb of equivalent relative density is also fabricated and tested. The energy absorbed for both specimens is computed from the resulting force-displacement curves. The beam geometry of the negative stiffness honeycomb is optimized for maximum energy absorption per unit mass of material. Findings – Negative stiffness honeycombs exhibit relatively large positive stiffness, followed by a region of plateau stress as the cell walls buckle, similar to regular hexagonal honeycombs, but unlike regular honeycombs, they demonstrate full recovery after compression. Representative specimens are found to absorb about 65 per cent of the energy incident on them. Optimizing the negative stiffness beam geometry can result in energy-absorbing capacities comparable to regular honeycombs of similar relative densities. Research limitations/implications – The honeycombs were subject to quasi-static displacement loading. To study shock isolation under impact loads, force-controlled loading is desirable. However, the energy absorption performance of the negative stiffness honeycombs is expected to improve under force-controlled conditions. Additional experimentation is needed to investigate the rate sensitivity of the force-displacement behavior of the negative stiffness honeycombs, and specimens with various geometries should be investigated. Originality/value – The findings of this study indicate that recoverable energy absorption is possible using negative stiffness honeycombs without sacrificing the high energy-absorbing capacity of regular honeycombs. The honeycombs can find usefulness in a number of unique applications requiring recoverable shock isolation, such as bumpers, helmets and other personal protection devices. A patent application has been filed for the negative stiffness honeycomb design.

Novel Design of Impact Attenuator for an 'Eco Challenge' Car

2012 ◽  
Vol 165 ◽  
pp. 237-241 ◽  
Author(s):  
Amir Radzi Ab Ghani ◽  
Ramlan Kasiran ◽  
Mohd Shahriman Adenan ◽  
Mohd Haniff Mat ◽  
Rizal Effendy Mohd Nasir ◽  
...  
Keyword(s):  
Energy Absorption ◽  
Impact Energy ◽  
High Energy ◽  
Absorption Capacity ◽  
Flat Plates ◽  
Final Design ◽  
High Energy Absorption ◽  
Energy Absorbing ◽  
Long Stroke ◽  
The Impact

Thin-walled metallic tubular structures are generally used as impact energy absorber in automotive structures due to their ease of fabrication and installation, high energy absorption capacity and long stroke. However, unlike a normal passenger car where the impact energy can be distributed throughout the whole structure, the impact energy absorbing system of an Eco-Challenge car is confined within a limited space on the front bulkhead. The challenge is to develop an impact attenuator system that can effectively absorb the impact energy within the given space and fulfil the specified rate of deceleration. This new design utilized the standard Aluminium 6063 circular tubes, cut and welded into specific configurations i.e. stacked toroidal tubes with central axial tube sandwiched between two flat plates. Two configurations were investigated; circular and square toroids. Explicit non-linear FEA software was used to determine the impact response i.e. energy absorption, impact force and rate of deceleration. Both configurations showed promising results but the configuration that can be readily fabricated was chosen as the final design.

Effects of Functionally Graded Cellular Core on Energy Absorption Response of Thin Walled Composite Axial Members

2016 ◽  
Author(s):  
Muhammad Ali ◽  
Khairul Alam ◽  
Eboreime Ohioma
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Deformation Mode ◽  
High Energy ◽  
Steel Tube ◽  
Absorption Capacity ◽  
Functionally Graded ◽  
Composite Tube ◽  
Thin Walled ◽  
Energy Absorbing

Thin walled axial members are typically used in vehicles’ side and front chassis to improve crashworthiness. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of presence of functionally graded cellular structures in thin walled members. A functionally graded aluminum cellular core in compact form was placed inside a steel square tube. The crushing behavior was modeled using ABAQUS/Explicit module. The variables affecting the energy absorbing characteristics, for example, deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were studied. An approximate 35% increase in the energy absorption capacity of steel tube was observed by adding aluminum graded cellular structure to the square tube. The aluminum graded structure crushed systematically in a layered manner and its presence as core supported the steel square tube side walls in transverse direction and postponed the local (tube) wall collapse. This resulted in composite tube undergoing larger localized folds as compared to highly compact localized folds, which appeared in the steel tube without any graded core. The variation in deformation mode resulted in increased stiffness of the composite structure, and therefore, high energy absorption by the structure. Further, a relatively constant crushing force was observed in the composite tube promoting lower impulse. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.

scholarly journals How Does Environmental Regulation Affect the Relationship between FDI and Technological Innovation: From the Perspective of Technology Transactions

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1264
Author(s):  
Meng Zeng ◽  
Lihang Liu ◽  
Fangyi Zhou ◽  
Yigui Xiao
Keyword(s):  
Environmental Regulation ◽  
Technological Innovation ◽  
Pollutant Emissions ◽  
Regulatory Effect ◽  
Host Countries ◽  
Regional Heterogeneity ◽  
Industrial Sectors ◽  
Reduction Effect ◽  
The Impact ◽  
The Relationship

Many studies have found that FDI can reduce the pollutant emissions of host countries. At the same time, the intensity of environmental regulation would affect the emission reduction effect of FDI in the host country. This study aims to reveal the internal mechanisms of this effect. Specifically, this paper studies the impact of FDI on technological innovation in China’s industrial sectors from the perspective of technology transactions from 2001 to 2019, and then analyzes whether the intensity of environmental regulation can promote the relationship. Results indicate that FDI promotes technological innovation through technology transactions. In addition, it finds that the intensity of environmental regulation significantly positively moderates the relationship between FDI and technological innovation, which is achieved by positively moderating the FDI–technology transaction relationship. Regional heterogeneity analysis is further conducted, and results show that in the eastern and western regions of China, FDI can stimulate technological innovation within regional industrial sectors through technology trading. Moreover, environmental regulation has a significant positive regulatory effect on the above relationship, but these effects are not supported by evidence in the central region of China.

scholarly journals Frozen/thawed meat quality associated with muscle fiber characteristics of porcine longissimus thoracis et lumborum, psoas major, semimembranosus, and semitendinosus muscles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huilin Cheng ◽  
Sumin Song ◽  
Gap-Don Kim
Keyword(s):  
Meat Quality ◽  
Muscle Fiber ◽  
Shear Force ◽  
Muscle Fibers ◽  
Frozen Storage ◽  
Meat Color ◽  
Pork Meat ◽  
Psoas Major ◽  
The Relationship

AbstractTo evaluate the relationship between muscle fiber characteristics and the quality of frozen/thawed pork meat, four different muscles, M. longissimus thoracis et lumborum (LTL), M. psoas major (PM), M. semimembranosus (SM), and M. semitendinosus (ST), were analyzed from twenty carcasses. Meat color values (lightness, redness, yellowness, chroma, and hue) changed due to freezing/thawing in LTL, which showed larger IIAX, IIX, and IIXB fibers than found in SM (P < 0.05). SM and ST showed a significant decrease in purge loss and an increase in shear force caused by freezing/thawing (P < 0.05). Compared with LTL, SM contains more type IIXB muscle fibers and ST had larger muscle fibers I and IIA (P < 0.05). PM was the most stable of all muscles, since only its yellowness and chroma were affected by freezing/thawing (P < 0.05). These results suggest that pork muscle fiber characteristics of individual cuts must be considered to avoid quality deterioration during frozen storage.

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