Thermal Expansion of Concretes: Case Study in Iowa

1995 ◽  
Vol 7 (4) ◽  
pp. 246-251 ◽  
Author(s):  
Udeme J. Ndon ◽  
K. L. Bergeson
Keyword(s):  
Thermal Expansion

Thermal expansion and dimensionality of a hydrogen bond network: a case study on dimorphic oxalic acid

CrystEngComm ◽  
2020 ◽  
Vol 22 (45) ◽  
pp. 7896-7902
Author(s):  
Suman Bhattacharya
Keyword(s):  
Hydrogen Bond ◽  
Thermal Expansion ◽  
Oxalic Acid ◽  
Intermolecular Interactions ◽  
Crystal Packing ◽  
Hydrogen Bond Network ◽  
Bond Network

Between 156 K–298 K the  oxalic acid polymorphs, α-C2 and β-C2 exhibit comparable volumetric thermal expansions which are correlated to the respective crystal packing and intermolecular interactions in the two forms.

Design of Nonperiodic Microarchitectured Materials That Achieve Graded Thermal Expansions

2016 ◽  
Vol 8 (5) ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Lucas A. Shaw ◽  
Todd H. Weisgraber ◽  
George R. Farquar ◽  
Chris D. Harvey ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Compliant Mechanism ◽  
System Level ◽  
Element Analysis ◽  
Ambient Temperatures ◽  
Thermal Expansion Coefficients ◽  
Layered Coatings ◽  
Unit Cells ◽  
Expansion Coefficients

The aim of this paper is to introduce an approach for optimally organizing a variety of nonrepeating compliant-mechanism-like unit cells within a large deformable lattice such that the bulk behavior of the lattice exhibits a desired graded change in thermal expansion while achieving a desired uniform stiffness over its geometry. Such lattices with nonrepeating unit cells, called nonperiodic microarchitectured materials, could be sandwiched between two materials with different thermal expansion coefficients to accommodate their different expansions and/or contractions induced by changing ambient temperatures. This capability would reduce system-level failures within robots, mechanisms, electronic modules, or other layered coatings or structures made of different materials with mismatched thermal expansion coefficients. The closed-form analytical equations are provided, which are necessary to rapidly calculate the bulk thermal expansion coefficient and Young's modulus of general multimaterial lattices that consist first of repeating unit cells of the same design (i.e., periodic microarchitectured materials). Then, these equations are utilized in an iterative way to generate different rows of repeating unit cells of the same design that are layered together to achieve nonperiodic microarchitectured material lattices such that their top and bottom rows achieve the same desired thermal expansion coefficients as the two materials between which the lattice is sandwiched. A matlab tool is used to generate images of the undeformed and deformed lattices to verify their behavior and an example is provided as a case study. The theory provided is also verified and validated using finite-element analysis (FEA) and experimentation.

Designing Microstructural Architectures With Thermally Actuated Properties Using Freedom, Actuation, and Constraint Topologies

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Kyle J. Lange ◽  
Christopher M. Spadaccini
Keyword(s):  
Thermal Expansion ◽  
Bulk Material ◽  
Negative Thermal Expansion ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Design Requirements ◽  
Expansion Coefficients ◽  
Thermally Actuated ◽  
Constraint Topologies

In this paper, we demonstrate how the principles of the freedom, actuation, and constraint topologies (FACT) approach may be applied to the synthesis, analysis, and optimization of microstructural architectures that possess extreme or unusual thermal expansion properties (e.g., zero or large negative-thermal expansion coefficients). FACT provides designers with a comprehensive library of geometric shapes, which may be used to visualize the regions wherein various microstructural elements can be placed for achieving desired bulk material properties. In this way, designers can rapidly consider and compare a multiplicity of microstructural concepts that satisfy the desired design requirements before selecting the final concept. A complementary analytical tool is also provided to help designers rapidly calculate and optimize the desired thermal properties of the microstructural concepts that are generated using FACT. As a case study, this tool is used to calculate the negative-thermal expansion coefficient of a microstructural architecture synthesized using FACT. The result of this calculation is verified using a finite element analysis (FEA) package called ale3d.

Cracks on ETICS along thermal insulation joints: case study and a pathology catalogue

2016 ◽  
Vol 34 (1) ◽  
pp. 57-72 ◽  
Author(s):  
Sara Stingl de Freitas ◽  
Vasco Peixoto de Freitas
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Thermal Insulation ◽  
Expansion Coefficient ◽  
Mechanical Behaviour ◽  
Climatic Conditions ◽  
Insulation Material ◽  
Content Type

Purpose – The purpose of this paper is to present a case study of cracks on external thermal insulation composite systems (ETICS) along the thermal insulation joints and the information available on the building pathology catalogue – PATORREB. The aim is to establish the methodology to study the cause of the pathology observed on a building which is located on the interior of Portugal based on in situ probing together with the analysis of hygrothermal and mechanical behaviour. Design/methodology/approach – An in situ analysis was performed to assess the causes. The hygrothermal dynamic behaviour of the wall was analysed with a numerical simulation advanced tool considering the climatic conditions, the characteristics of the thermal insulation plates as well as the support and finishing layer properties. Moreover, a qualitatively analysis of the mechanical behaviour, based on the bonding process, thermal insulation and exterior rendering properties was performed. Findings – It was concluded that the insulation properties – thermal expansion coefficient and stiffness, the thermal expansion coefficient of the exterior rendering, together with adverse climatic conditions were critical for the appearance of cracks along the plate joints, particularly with spot bonding. The expansion and retraction stresses and the restrained movements of the components can result in bending moments, especially when the insulation material has a high stiffness value, which will create the crack on the rendering system. Originality/value – A combination between a hygrothermal and mechanical analysis of an ETICS pathology concerning the appearance of cracks with a subsequent integration into a building pathology catalogue.

System-Wide Response to Incidents: Case Study

2016 ◽  
Author(s):  
S. Zhang ◽  
S. Kariyawasam ◽  
R. Sutherby ◽  
J. Upadhyaya
Keyword(s):  
Risk Assessment ◽  
Thermal Expansion ◽  
Management Program ◽  
Energy Industry ◽  
Major Incident ◽  
Pipeline System ◽  
Contributing Factors ◽  
Major Incidents ◽  
Integrity Management

This paper presents a systematic and comprehensive procedure for the system-wide response to incidents (SWRI). This SWRI process has been used for identifying emerging threats and incorporating the learnings from major incidents into a pipeline integrity management program (IMP). This process also complements the IMP for threat identification and system wide risk assessment, thus giving consideration to all known threats and their interactions. A recent major incident due to thermal expansion on a TransCanada pipeline system was used to demonstrate the process of SWRI and the use of SWRI to identify the contributing factors of thermal expansion. An example was used to illustrate the engineering assessment for thermal expansion driven by the construction of two new compressor stations on an existing pipeline. The process documented in this case study has the potential to augment the integrity management programs and systemic corrective actions for pipeline systems in the energy industry.

Valve Operability During a Fire

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Karan Sotoodeh
Keyword(s):  
Thermal Expansion ◽  
The Body ◽  
Valve Body ◽  
Gas Processing ◽  
Oil Export ◽  
Closed Position ◽  
Fire And Explosion ◽  
Open Position ◽  
Refinery Gas

Fire and explosion are a major cause of concern for refinery, gas processing, petrochemical, and gas installations. The safest way to deal with a fire is to prevent it. However, fire prevention strategies are not always successful, and fires can happen. Therefore, valves should be designed and tested to be fire-safe. This paper reviews valve design features that can help prevent fires, including secondary sealing between the ball and body in case of losing a soft seat, a graphite fire-safe ring design for stem and seat sealing, antistatic devices, and antistatic tests to ensure that the valve is fire-safe. In addition to design considerations, a fire-safe design should be validated through tests defined in standards such as API 607, API RP 6FA, and ISO 10497. The API RP 6FA tests reviewed in this paper include seven tests that check the operability of the valve from closed to open position. A case study was done to prove the operability of a fail close 38″ pipeline ball valve on an oil export pipeline in case of fire during the first 20 s from the open to the closed position. Thermal analysis on the body of the valve proved that there was no thermal expansion inside the valve after 150 s of fire. Additionally, the maximum radial displacement on the valve body after 150 s of fire was 0.34 mm which is negligible. Thus, the valve thermal expansion did not disturb the operation of the valve after 20 s.

Synthesizing the Compliant Microstructure of Thermally Actuated Materials Using Freedom, Actuation, and Constraint Topologies

2012 ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Kyle J. Lange ◽  
Christopher M. Spadaccini
Keyword(s):  
Thermal Expansion ◽  
Screw Theory ◽  
Bulk Material ◽  
Negative Thermal Expansion ◽  
Thermal Expansion Coefficients ◽  
Final Design ◽  
Expansion Coefficients ◽  
Thermally Actuated ◽  
Constraint Topologies

The aim of this paper is to demonstrate how the principles of the Freedom, Actuation, and Constraint Topologies (FACT) synthesis approach may be applied to the design of compliant microstructural architectures that possess extreme or unusual thermal expansion properties (e.g., zero or large negative thermal expansion coefficients). FACT provides designers with a comprehensive library of geometric shapes, which may be used to visualize the regions wherein various microstructural elements can be placed for achieving desired bulk material properties. In this way, designers can rapidly consider and compare every microstructural concept that best satisfies the design requirements before selecting the final design. A screw-theory-based analytical tool is also provided in this paper to help designers calculate and optimize the thermal properties of microstructural concepts, which are generated using FACT. As a case study, this tool is used to calculate the negative thermal expansion coefficient of a microstructural architecture synthesized using FACT.

scholarly journals Effect of Tapered Interference Fit between Impeller and Shaft in Turbo Machines

2018 ◽  
Vol 68 (3) ◽  
pp. 25-32
Author(s):  
Nilesh Vishwakarma ◽  
Avinash Renuke ◽  
V.M. Phalle
Keyword(s):  
Thermal Expansion ◽  
Contact Pressure ◽  
Centrifugal Compressor ◽  
Transient Condition ◽  
Interference Fit ◽  
Transfer Capability ◽  
Higher Temperature ◽  
Effective Analysis ◽  
Healthy Contact

AbstractIn Turbo machines, there are many components which are provided with interference to transmit torque and to maintain contact between them. There are transient scenarios where impeller and shaft lose interference and limits the speed of the impeller. In this paper, a case study on centrifugal compressor has been presented to see the effect of taper pairing of shaft with impeller. When the centrifugal compressor starts then a transient condition is dominant wherein the impeller of the centrifugal compressor gains higher temperature quickly compared to shaft. Since the thermal expansion of the impeller will be much more than the shaft, interference between impeller and shaft is likely to reduce. With reduced interference, the impeller should retain minimum required contact pressure with the shaft and the torque transmitting capability. For conventional fitted impeller, stress built up is a major concern especially at higher speeds. This paper gives a proposal about the importance of tapered interference fit method compared to cylindrical fitted impeller assembly. An effective analysis between the conventional straight fitted impeller and impeller having tapered bore is presented for the same torque transfer capability. The analysis reveals that for the impeller with tapered bore, the stress for impeller reduces and a healthy contact pressure exists.

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