Effect of Compliance on Residual Stresses in Manufacturing with Moving Heat Sources

2021 ◽  
pp. 1-53
Author(s):  
Mitchell R. Grams ◽  
Patricio F. Mendez
Keyword(s):  
Residual Stresses ◽  
Thermal Stresses ◽  
Ad Hoc ◽  
Mathematical Treatment ◽  
Heat Sources ◽  
Plastic Part ◽  
Practical Applications ◽  
Tendon Force ◽  
Design Calculations ◽  
Force Concept

Abstract Manufacturing processes involving moving heat sources include additive manufacturing, welding, laser processing (cladding and heat treatment), machining, and grinding. These processes involve high local thermal stresses that induce plasticity and result in permanent residual stress and distortion. The residual stresses are typically calculated numerically at great computational expense despite the fact that the inelastic fraction of the domain is very small. Efforts to decouple the small plastic part from the large elastic part have led to the development of the tendon force concept. The tendon force can be predicted analytically for the case of infinitely rigid components; however, this limitation has prevented the broader use of the concept in practical applications. This work presents a rigorous mathematical treatment using dimensional analysis, asymptotics, and blending which demonstrates that the effect of geometric compliance depends on a single dimensionless group, the Okerblom number. Closed-form expressions are derived to predict the effect of compliance without the need for empirical ad-hoc fitting or calibration. The proposed expressions require input of only material properties and tabulated process parameters, and are thus ideally suited for use in metamodels and design calculations, as well as incorporation into engineering codes and standards.

Large qualitative models of complex chemical and bioengineering processes

1991 ◽  
Vol 56 (10) ◽  
pp. 2107-2141 ◽  
Author(s):  
Mirko Dohnal
Keyword(s):  
Case Studies ◽  
Chemical Process ◽  
Ad Hoc ◽  
Chemical Reactor ◽  
Theoretical Background ◽  
Qualitative Model ◽  
Complex Chemical ◽  
Practical Applications ◽  
Qualitative Models ◽  
Decomposition Principle

Qualitative model is a theoretical background of commonsense. Complex qualitative models can have prohibitively many solutions (qualitative states). Therefore a qualitative analogy of such classical quantitative tools as e.g. the decomposition is developed. Practical applications of decomposition principle is nearly always ad hoc. Therefore two case studies are presented in details, a chemical process (mixer, chemical reactor, separator) and an anaerobic fermentor.

A Concept of a “Virtual Production Line” Produced by Integrating Databases and Models of Materials

MRS Bulletin ◽  
1993 ◽  
Vol 18 (7) ◽  
pp. 29-34 ◽  
Author(s):  
Shuichi Iwata
Keyword(s):  
Production Line ◽  
Ad Hoc ◽  
Intelligent System ◽  
Processing Parameters ◽  
Alloy Development ◽  
Bottom Up ◽  
Vast Number ◽  
Practical Applications ◽  
Virtual Production ◽  
Almost All

One of the requirements for an intelligent system is to construct a virtual reality in the computer. For materials development, the “reality” is a laboratory or a production line used to improve some aspect of a material by changing its composition, processing parameters, service conditions, etc. In the case of information in libraries, the reality is a search that uses a thesaurus and bibliographic (fact) databases. The greatest barrier faced by users of materials information is that of accessing necessary information through both a librarian's view and a scientific/technological expert's view. One of the objectives of a virtual production line is to reduce this barrier through user-friendly interfaces.In designing materials, two typical approaches are combined to solve a given problem. The first is a top-down approach, in which a number of requirements are resolved to a set of possible and practical solutions for satisfying these requirements to a certain level. Almost all alloy development has followed such an approach. The second approach is a bottom-up approach, where different materials properties are described on the basis of underlying theories, preferably using first principles and fundamental data. But the vast number of possible materials makes the bottom-up approach unrealistic on its own. Instead, semi-empirical approaches are needed to bridge the gap between ad hoc data sets for practical applications and results produced by the bottom-up approach using fundamental data and first-principle calculations.

scholarly journals An Elastoplastic Thermal-Stress Analysis of a Free Plate

1956 ◽  
Vol 23 (3) ◽  
pp. 395-402
Author(s):  
Jerome Weiner
Keyword(s):  
Thermal Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Uniqueness Theorem ◽  
Unique Solution ◽  
Heat Input ◽  
Thermal Stresses ◽  
Elastoplastic Material ◽  
Heuristic Solution ◽  
Peak Magnitude

Abstract The thermal stresses in a free plate of elastoplastic material subjected to a varying heat input over one face are determined. A heuristic solution is first found by suitable modifications of the known elastic solution. It is then verified that the solution satisfies all the conditions of the appropriate uniqueness theorem and represents therefore the unique solution to the problem. Residual stresses are determined and found to depend markedly on the peak magnitude of the heat input.

Residual Stress Analysis in Different Thickness TiN Coatings on High-Speed-Steel Substrates

2011 ◽  
Vol 239-242 ◽  
pp. 2331-2335 ◽  
Author(s):  
Fang Mei ◽  
Guang Zhou Sui ◽  
Man Feng Gong
Keyword(s):  
Residual Stresses ◽  
High Speed ◽  
Thermal Stresses ◽  
High Speed Steel ◽  
X Ray Diffraction ◽  
Tin Coatings ◽  
Compressive Stresses ◽  
M2 High Speed Steel ◽  
Steel Substrates ◽  
Different Thickness

TiN coatings were deposited on AISI M2 high-speed-steel (HSS) substrates by multi-arc ion plating technique. The thickness of substrate was 1.0 mm and five thicknesses of TiN coatings were 3.0, 5.0, 7.0, 9.0 and 11.0 μm, respectively. X-ray diffraction (XRD) has been used for measuring residual stresses. The stresses along five different directions (Ψ=0°, 20.7°, 30°, 37.8° and 45°) have been measured by recording the peak positions of TiN (220) reflection for each 2θ at different tilt angles Ψ. Residual compressive stresses present in the TiN coatings. Furthermore, the results revealed that the value of the residual stresses in TiN coatings was high. While the coatings thickness changed from 3 to 11 μm, the residual stresses varied from -3.22 to -2.04 GPa, the intrinsic stresses -1.32 to -0.14 GPa, the thermal stresses -1.86 to -1.75 GPa. The residual stresses in TiN coatings showed a nonlinear change. When the coatings thickness was about 8 μm, the residual stresses in TiN coatings reached to the maximum value.

Effect of Interfacial Nanostructure on Mode Mixity in Directly Bonded Carbon Fiber Reinforced Thermoplastic Laminates and Aluminum Alloy With Thermal Stresses

2020 ◽  
Author(s):  
Hiroki Ota ◽  
Kristine Munk Jespersen ◽  
Kei Saito ◽  
Keita Wada ◽  
Kazuki Okamoto ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Carbon Fiber ◽  
Residual Stresses ◽  
Adhesive Bonding ◽  
Thermal Stresses ◽  
Fiber Reinforced ◽  
Mode Mixity ◽  
Mechanical Joining ◽  
Carbon Fiber Reinforced

Abstract In recent years, for the aim of weight reduction of transportation equipment, carbon fiber reinforced thermoplastics (CFRTPs), which have high recyclability and formability, are becoming suitable for mass production. Additionally, with the development of multi-material structures, excellent technologies for joining metal and CFRTPs are required. In present industry, joining between dissimilar materials include adhesive bonding and mechanical joining methods, however, these methods still have some problems, and therefore an alternative bonding method without adhesive and mechanical joining is required for joining CFRTPs and metals. Thus, this study focused on direct bonding between CFRTP and an aluminum alloy, by producing a nanostructure on the surface of the aluminum alloy. The nanostructure penetrates the CFRTP matrix causing an anchoring effect, which results in significant bonding strength improvement. The influence of the nanostructure on the fracture toughness for the directly bonded CFRTP and aluminum was evaluated by static double cantilever beam (DCB) testing. Due to the difference of the thermal expansion coefficients between the CFRTP laminates and the aluminum alloy, significant residual stresses are generated. The effect of the thermal residual stresses on the fracture toughness along with the resulting mode mixity (mode I and II) was calculated. It is found that the thermal stresses introduce a significant mode mixity of the fracture toughness.

Formation of transition-metal-based ohmic contacts to n-Mg2Si by Plasma Activated Sintering

2007 ◽  
Vol 1044 ◽  
Author(s):  
Yohei Oguni ◽  
Tsutomu Iida ◽  
Atsunobu Matsumoto ◽  
Takashi Nemoto ◽  
Junichi Onosaka ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Thermal Stresses ◽  
Electrode Materials ◽  
Open Circuit ◽  
Activated Sintering ◽  
Practical Applications ◽  
Thermal Expansion Coefficients ◽  
Good Crystalline Quality ◽  
The Difference ◽  
Plasma Activated Sintering

AbstractElectrode materials consisting of Cu, Ti and Ni were formed on Bi-doped n-type Mg2Si by means of a monobloc plasma-activated sintering (PAS) technique. Due to the difference in thermal expansion coefficients between Ti and Mg2Si, rather high residual thermal stresses gave rise to the introduction of cracks, which were mainly located in the Mg2Si layer, when Ti was used as the electrode material. In the case of the Cu electrodes, monobloc sintering could not be performed in a reproducible manner because Cu melts abruptly and effuses at around 973K, which is 100 K lower than the sintering temperature that is required for Mg2Si of good crystalline quality. When compared with the results for Cu and Ti, the monobloc PAS process for Ni was both stable and reproducible. The room-temperature I-V characteristics of Ni electrodes were considered to be adequate for practical applications, with durable Mg2Si-electrode junction properties being realized at a practical operating temperature of 600 K with ΔT = 500 K. The highest open circuit voltage (VOC) observed was 41 mV at ΔT = 500 K (between 873 K and 373 K) for Ni electrodes fabricated using the monobloc PAS process. The voltage (V) and current (I) values with a 10 Ohm load were ∼ 48 mV and ∼ 2 mA at ΔT = 500 K.

Measurement of residual stresses and distortions in stiffened panels

1977 ◽  
Vol 12 (2) ◽  
pp. 107-116 ◽  
Author(s):  
W L Somerville ◽  
J W Swan ◽  
J D Clarke
Keyword(s):  
Residual Stresses ◽  
Elastic Strain ◽  
Welded Structures ◽  
Stiffened Panels ◽  
Buckling Strength ◽  
Ship Hulls ◽  
Future Design ◽  
Design Calculations ◽  
Initial Results

Methods for measuring residual stresses and distortions in welded structures are described and initial results are given of a survey being carried out during manufacture of warship hull sections. The stresses are determined by measuring the elastic strain induced in the plate and stiffeners due to contraction of the stiffener welds, and profiles of the stiffener and plating after welding have been obtained. The survey is intended to provide information for use in future design calculations of the buckling strength of ship hulls.

Invsetigation about Residual Stresses of Plasma-Spraying Sm2Zr2O7/YSZ Thermal Barrier Coatings of Different Substrate Conditions

2011 ◽  
Vol 308-310 ◽  
pp. 1177-1181 ◽  
Author(s):  
Hong Song Zhang ◽  
Gang Yi Cai ◽  
Shu Sen Yang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plasma Spraying ◽  
Thermal Stresses ◽  
Thermal Barrier ◽  
Shear Stresses ◽  
Substrate Thickness ◽  
Optimum Thickness ◽  
Slight Effect ◽  
Axial Residual Stress

Effect of substrate conditions, including material type, thickness and radius of substrate, on residual thermal stresses of plasma spraying Sm2Zr2O7/YSZ TBCs was analyzed through finite element method in this paper. The radial and shear stresses of the coating decrease with increasing of distance from the center to edge, and they decrease abruptly at the edge of the specimen, while the axial residal stress increase abruptly at the edge of substrate. All residual stresses increase with increasing of thermal expansion coefficient of substrate. The thickness of substrate has slight effect on the radial residual stress, axial residual stress and shear stress are almost uneffected by substrate thickness. The optimum thickness of substrate is 10mm. Radius of substrate have no effect on radial stress when it is greater than 28mm.

Calculation of a Premixed Swirl Combustor Using the PDF Method

1997 ◽  
Author(s):  
A. T. Hsu ◽  
M. S. Anand ◽  
M. K. Razdan
Keyword(s):  
Ad Hoc ◽  
Turbulent Flame ◽  
Reaction Rates ◽  
Turbulent Flames ◽  
Swirl Combustor ◽  
Turbulent Flame Speed ◽  
Premixed Turbulent Flames ◽  
Low Emission ◽  
Design Calculations ◽  
Complex Chemistry

The evolution probability density function (PDF) method provides a framework for the simulation of both diffusion and premixed turbulent flames. With this method, the chemical reaction rates are treated without approximation. In contrast, the conventional Reynolds-average methods need to model the mean reaction rates in turbulent flame calculations. In addition, conventional methods require special models for premixed flames that are developed under restrictive assumptions and rely on ad hoc expressions for the rate of reaction progress. The present work demonstrates the capability of the PDF method in realistic combustor design calculations. A lean premixed flame swirl combustor is simulated using the scalar PDF method, and the results are compared with experimental data. It is shown that the PDF method can correctly predict the turbulent flame speed and location of the flame. The ability of the PDF method to handle finite-rate complex chemistry of any number of reaction steps makes it an ideal candidate for emissions predictions in low emission combustor designs.

Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating

2006 ◽  
Author(s):  
Takuro Terajima ◽  
Takashi Hirano
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Induction Heating ◽  
Weld Joint ◽  
Thermal Stresses ◽  
Pressure Vessels ◽  
Weld Joints

As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants’ reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following. i) Investigation of IHSI conditions (Essential Variables); ii) Residual stresses after IHSI; iii) Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint.

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