scholarly journals Variation of Mechanical Characteristics of Polyurethane Foam: Effect of Test Method

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2672 ◽  
Author(s):  
Ki-Beom Park ◽  
Hee-Tae Kim ◽  
Nam-Yong Her ◽  
Jae-Myung Lee
Keyword(s):  
Polyurethane Foam ◽  
Evaluation Method ◽  
Mechanical Performance ◽  
Cell Structure ◽  
Extreme Environments ◽  
Evaluation Criteria ◽  
Test Method ◽  
Material Behavior ◽  
Insulation Material ◽  
Binding Effect

Polyurethane foam (PUF), a representative insulation material, not only prevents heat conduction but can also support a load. Particular interest in rigid PUF proliferated over the past several years in fields where extreme environments are applied. A closed-cell structure which forms the interior of rigid PUF serves to maximize the utilization of these polymeric foams. Rigid PUF is more sensitive to external conditions such as temperature or restraint than other structural materials such as steel. Depending on the market trends in which utilization of a cryogenic environment is expanding, the tendency of material behavior resulting from the binding effect also needs to be investigated. However, most conventional compression test method standards applicable to rigid PUF do not adequately reflect the restraints. Therefore, this study proposes a method for evaluating the mechanical performance of materials in a more reliable manner than that of conventional tests. Experimental observation and analysis validated this compression evaluation method in which constraints are considered. Consequently, the compressive strength of rigid PUF compared to the results of the conventional test showed a difference of up to 0.47 MPa (approximately 23%) at cryogenic temperatures. This result suggests that there are important factors to consider when assessing performance from a material perspective in an environment where rigid PUF insulation is utilized. It is believed that the test methods newly proposed in this study will provide an experimental framework that can be applied to the evaluation criteria of material properties and reflected in structural design.

Robust Test Method of TSOP PEMs for Space Application

2019 ◽  
Author(s):  
Yasunobu Iwai ◽  
Koichi Shinozaki ◽  
Daiki Tanaka
Keyword(s):  
Evaluation Method ◽  
Low Cost ◽  
Reliability Evaluation ◽  
Test Method ◽  
Thermal Shock Test ◽  
Space Application ◽  
Space Applications ◽  
Limit Test ◽  
Long Time ◽  
Short Time

Abstract Compared with space parts, consumer parts are highly functional, low cost, compact and lightweight. Therefore, their increased usage in space applications is expected. Prior testing and evaluation on space applicability are necessary because consumer parts do not have quality guarantees for space application [1]. However, in the conventional reliability evaluation method, the test takes a long time, and the problem is that the robustness of the target sample can’t be evaluated in a short time. In this report, we apply to the latest TSOP PEM (Thin Small Outline Package Plastic Encapsulated Microcircuit) an evaluation method that combines preconditioning and HALT (Highly Accelerated Limit Test), which is a test method that causes failures in a short time under very severe environmental conditions. We show that this method can evaluate the robustness of TSOP PEMs including solder connections in a short time. In addition, the validity of this evaluation method for TSOP PEM is shown by comparing with the evaluation results of thermal shock test and life test, which are conventional reliability evaluation methods.

scholarly journals Thermal, Physical and Mechanical Performance of Orange Peel Boards: A New Recycled Material for Building Application

2021 ◽  
Vol 13 (14) ◽  
pp. 7945
Author(s):  
Matteo Vitale ◽  
María del Mar Barbero-Barrera ◽  
Santi Maria Cascone
Keyword(s):  
Thermal Conductivity ◽  
Bending Strength ◽  
Mechanical Performance ◽  
Orange Peel ◽  
Insulation Material ◽  
Orange Peels ◽  
Orange Fruit ◽  
Citrus Waste ◽  
Absorption Thickness ◽  
Loss Of Strength

More than 124 million tons of oranges are consumed in the world annually. Transformation of orange fruit generates a huge quantity of waste, largely composed of peels. Some attempts to reuse by-products derived from citrus waste have been proposed for energy production, nutrient source or pharmaceutical, food and cosmetic industries. However, their use in the building sector had not been researched. In this study, orange peels, in five different ratios, from 100% of wet peels to 75% and from 0% of dry peels to 25%, were submitted to a thermo-compression procedure. They were evaluated according to their physical (bulk density, water absorption, thickness swelling, surface soundness and thermal conductivity) and mechanical properties (bending strength and modulus of elasticity). The results showed that orange peels can be used as thermal insulation material. The addition of dried peels makes the structure of the board heterogeneous and thus increases its porosity and causes the loss of strength. Hence, the board with the sole use of wet peel, whose thermal conductivity is 0.065 W/mK while flexural strength is 0.09 MPa, is recommended.

A Study of the Influence of Polymer and Cell Structure on Polyurethane Foam Properties for Better Riding Comfort

2020 ◽  
pp. 267-274
Author(s):  
Masahiro Isobe ◽  
Kazuto Usaka ◽  
Hiroyuki Utsumi ◽  
Kazuhiko Ohkubo
Keyword(s):  
Polyurethane Foam ◽  
Cell Structure ◽  
Foam Properties

Fire Risk Assessment of Fire Retardant Polyurethane Thermal Insulation Materials for Exterior Walls of Buildings Based on Analytical Hierarchy Process

2013 ◽  
Vol 785-786 ◽  
pp. 191-198
Author(s):  
Li Jun Li ◽  
Feng Li ◽  
Ze Jiang Zhang
Keyword(s):  
Thermal Insulation ◽  
Evaluation Method ◽  
Fire Hazard ◽  
Fire Retardant ◽  
Fire Risk ◽  
Insulation Material ◽  
Test Results ◽  
Analytic Hierarchy ◽  
Rigid Foam ◽  
Hierarchy Process

Different flame retardant contents of polyurethane rigid foam (PRF) were prepared in this paper. Combustion performances of PRF were tested by cone calorimeter (CONE). Fire risk of PRF was evaluated based on Analytic Hierarchy Process (AHP). The evaluation results were compared with the traditional LOI results. It was found that the evaluation method based on AHP combined with CONE test results for evaluating fire hazard of thermal insulation material for exterior walls of buildings is more accurate and objective compared with the method of the traditional LOI.

Evaluation of the Development Level of China' s Precise Finishing Industry

2006 ◽  
Vol 315-316 ◽  
pp. 864-867
Author(s):  
Shi An ◽  
J. Wang ◽  
J.P. Qian
Keyword(s):  
Analytical Hierarchy Process ◽  
Evaluation Method ◽  
Expert Knowledge ◽  
Comprehensive Evaluation ◽  
Evaluation Criteria ◽  
Development Planning ◽  
Fuzzy Evaluation ◽  
Fuzzy Analytical Hierarchy Process ◽  
Development Level ◽  
Hierarchy Process

Recognizing and evaluating the development level of a country’s precise finishing industry, is the prerequisite to the country’s decision-making on the development planning and guiding policies in this industry. This paper presents a Fuzzy Analytical Hierarchy Process (FAHP) Model on the base of “Expert Knowledge”. This model combines the advantages of Fuzzy Evaluation Method and Analytical Hierarchy Process (AHP), and can give relatively reliable evaluation results with incomplete information of the evaluation criteria. The application of the FAHP Model provide reliable comprehensive evaluation data.

scholarly journals Evaluation Method of Relative Humidity Changes in Below-Grade Concrete Structure Space Depending on Different Waterproofing Material and Installation Method

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 742
Author(s):  
Ki-won An ◽  
Kyu-hwan Oh ◽  
Bo Jiang ◽  
Xingyang He ◽  
Sang-keun Oh
Keyword(s):  
Relative Humidity ◽  
Linear Regression ◽  
Concrete Structure ◽  
Evaluation Method ◽  
Linear Regression Analysis ◽  
Evaluation Criteria ◽  
Cumulative Probability ◽  
Control Performance ◽  
Negative Side ◽  
Positive Side

An evaluation method for assessing the difference in the relative humidity (RH) control performance of waterproofing material is proposed. For a demonstration of this evaluation method, two waterproofing materials (urethane coating and cementitious waterproofing material) installed with different methods (positive and negative side of concrete structure respectively) are exposed to temperature conditions representing three seasonal conditions: Summer (40 °C), spring/autumn (20 °C) and winter (4 °C). Condensation level changes on the inner side of the waterproofing material installed specimen is measured, and for derive criteria for comparison, three parameters based on the average RH, intercept RH (derived from a linear regression analysis of RH measurement), and maximum relative humidity are derived for each different waterproofing material installed specimen. Based on quality specification for underground concrete structures, the demonstration evaluation establishes provisional standard criteria of below 70% RH, and all three parameters are evaluated to determine whether the tested waterproofing material/method complies to the performance requirement. Additional analysis through linear regression and cumulative probability density graphs are derived to evaluate the RH consistency and range parameters. The evaluation regime demonstrates a quantitative RH analysis method and apparatus, and a newly designed evaluation criteria is used to compare the RH control performance of positive-side installed urethane waterproofing materials and negative-side installed cementitious waterproofing material.

scholarly journals Technical Evaluation Method for Physical Property Changes due to Environmental Degradation of Grout-Injection Repair Materials for Water-Leakage Cracks

2019 ◽  
Vol 9 (9) ◽  
pp. 1740 ◽  
Author(s):  
Jiang ◽  
Oh ◽  
Kim ◽  
He ◽  
Oh
Keyword(s):  
Environmental Degradation ◽  
Evaluation Method ◽  
Physical Property ◽  
Performance Comparison ◽  
Test Method ◽  
Grout Injection ◽  
Chemical Corrosion ◽  
Technical Evaluation ◽  
Injection Materials ◽  
Property Changes

Leakage in below-grade concrete structures are repaired using various types of grout-injection materials, but the selection of optimal material types with a consideration of the environmental degradation factors are not conducted. Different degradation factors can act on the waterproofing membranes or grout-injection materials simultaneously. Especially in the early stages of installation, the injected grout materials in the cracks for leakage repair or for reforming damaged waterproofing layers are subject to complex forms of degradation factors. In such cases, physical property changes to the materials can reduce the waterproofing performance of the grout-injection materials. In this study, a technical evaluation regime is proposed for selecting the optimal repair material to be used in underground concrete structure leakage cracks. In this study, six environmental degradation factors (thermal stress, chemical corrosion, erosion due to ground water flow, hydrostatic pressure, substrate movement, and humidity on concrete surface) are identified. Corresponding evaluation methods based on the ISO TS 16774 test method series were used for each factor to assess the performance evaluation of four different types of grout-injection materials (acrylic resin, epoxy resin, polyurethane foam, and synthetic polymerized rubber gel). Based on the test results, a new comprehensive evaluation regime is presented that allows a quantitative performance comparison between each type of grout-injection material.

scholarly journals A Cross-Efficiency Evaluation Method Based on Evaluation Criteria Balanced on Interval Weights

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1503 ◽  
Author(s):  
Hailiu Shi ◽  
Yingming Wang ◽  
Xiaoming Zhang
Keyword(s):  
Evaluation Method ◽  
Evaluation Criteria ◽  
Evaluation Criterion ◽  
Peer Evaluation ◽  
Data Envelopment ◽  
Efficiency Evaluation ◽  
Common Set Of Weights ◽  
The Cross ◽  
The Difference ◽  
Evaluation Approaches

Cross-efficiency evaluation approaches and common set of weights (CSW) approaches have long been suggested as two of the more important and effective methods for the ranking of decision making units (DMUs) in data envelopment analysis (DEA). The former emphasizes the flexibility of evaluation and its weights are asymmetric, while the latter focuses on the standardization of evaluation and its weights are symmetrical. As a compromise between these two approaches, this paper proposes a cross-efficiency evaluation method that is based on two types of flexible evaluation criteria balanced on interval weights. The evaluation criteria can be regarded as macro policy—or means of regulation—according to the industry’s current situation. Unlike current cross-efficiency evaluation methods, which tend to choose the set of weights for peer evaluation based on certain preferences, the cross-efficiency evaluation method based on evaluation criterion determines one set of input and output weights for each DMU. This is done by minimizing the difference between the weights of the DMU and the evaluation criteria, thus ensuring that the cross-evaluation of all DMUs for evaluating peers is as consistent as possible. This method also eliminates prejudice and arbitrariness from peer evaluations. As a result, the proposed cross-efficiency evaluation method not only looks for non-zero weights, but also ranks efficient DMUs completely. The proposed DEA model can be further extended to seek a common set of weights for all DMUs. Numerical examples are provided to illustrate the applications of the cross-efficiency evaluation method based on evaluation criterion in DEA ranking.

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