Deformation Capacity of Web Perforated H-Shaped Beams

2018 ◽  
Author(s):  
Toru Inaba ◽  
Tetsu Usami ◽  
Kenji Yamazaki ◽  
Fumi Ushiwata ◽  
Nobuyuki Odajima ◽  
...  
Keyword(s):  
Stress State ◽  
Design Method ◽  
Deformation Capacity ◽  
Elastic State ◽  
Acting Stress ◽  
The Relationship

<p>When designing web perforated H-shaped beams, it is common to reinforce the holes due to the deficit in section’s area. However, previous studies revealed that non-reinforced web-perforated H-Shaped beams had similar performances as non-perforated H-shaped beams without holes when the position and shape of holes were designed considering the relationship between the acting stress for beams and the strength at the reduced sections. While this design method of non-reinforced web perforated H-shaped beams assumes a stress state of beams in the elastic state, it cannot always guarantee an appropriate performance in the ultimate stage similarly to non-perforated H-shaped beams. So the purpose of this study is to confirm the ultimate behavior of perforated H-shaped beams by experiment and FEM.</p>

Minimum Energy Control of Multibody Systems Utilizing Storage Elements

2009 ◽  
Author(s):  
Werner Schiehlen ◽  
Makoto Iwamura
Keyword(s):  
Multibody Systems ◽  
Optimal Trajectory ◽  
Design Method ◽  
Equations Of Motion ◽  
Minimum Energy ◽  
Operating Time ◽  
Minimum Energy Control ◽  
Robot Systems ◽  
Optimal Design Method ◽  
The Relationship

In this paper, we consider the problem to minimize the energy consumption for controlled multibody systems utilizing passive elastic elements for energy storage useful for robot systems in manufacturing. Firstly, based on the linearized equations of motion, we analyze the relationship between the consumed energy and the operating time, and the optimal trajectory using optimal control theory. Then, we verify the analytical solution by comparing with the numerical one computed considering the full nonlinear dynamics. After that we derive a condition for the operating time to be optimal, and propose the optimal design method for springs. Finally, we show the effectiveness of the design method by applying it to a 2DOF manipulator.

A synergy-column envelope meshing pair profile for single screw compressors

2018 ◽  
Vol 233 (4) ◽  
pp. 1383-1391 ◽  
Author(s):  
Feilong Liu ◽  
Junhao Feng ◽  
Jia Xie ◽  
Quanke Feng ◽  
Martijn Van Den Broek ◽  
...  
Keyword(s):  
Design Method ◽  
Optimal Combination ◽  
Stable Operation ◽  
Single Screw ◽  
Tooth Width ◽  
Operational Life ◽  
Column Design ◽  
Manufacturing Methods ◽  
Operation Results ◽  
The Relationship

Multi-column envelope engaging couples have been proposed for single screw compressors to reduce the friction and prolong the operational life. However, little is mentioned about the relationship between columns at opposite sides of the star-wheel teeth. An imbalance in the lubricant film forces would appear and influence the lubrication between the tooth and the groove. During a real design process, it is necessary to try several times for each different type of compressor to find the optimal combination of columns. In part, due to the large number of columns, it also makes both manufacturing processing and product testing difficult. In this paper, a synergy-column design method and its related manufacturing methods are presented. The locations and relationships of the designed columns can be prescribed by given the tooth width. Manufacturing of the rotor and star-wheel shows the new design method can be more efficient through processing. The stable operation results prove that the synergy-column envelope meshing pair can solve the star-wheel’s wear-out problem.

scholarly journals Analysis of Post Loan Disbursement Allocation and Performance of Non-Prime Household Loan in Microfinance Banks in Kenya

2017 ◽  
Vol 03 ◽  
pp. 42
Author(s):  
Bernard Ndirangu Wachira ◽  
Humphrey Opiyo Omondi ◽  
Josphat K. Kinyanjui ◽  
◽  
◽  
...  
Keyword(s):  
Financial Management ◽  
Design Method ◽  
Wald Test ◽  
Grameen Bank ◽  
Credit Risks ◽  
Training Policy ◽  
The Government ◽  
And Performance ◽  
Descriptive Survey ◽  
The Relationship

The part played by non-prime household loans in improving the lives of many people who cannot afford collateral globally cannot be ignored. Many Microfinance Banks in many economies worldwide have tried to maintain the Grameen Bank Model of granting microloans, mainly non-prime household loans. However, the credit risks associated with this initiative hamper the pace at which the granting of this credit facility is expected to grow. This study intends to explore the relationship between the post loan disbursement allocation and the performance of non-prime household loans in the Microfinance Banks in Kenya. The theory associated to this study is the Credit Risk Theory. This theory, which is regarded as credit structural theory, was developed by Merton in 1972. The descriptive survey research design method was applied, and the sample size was 150 respondents. The data-collection tool used was a questionnaire. A logistic regression analysis was conducted for the purpose of predicting non-prime household performance in the Microfinance Banks using training budget, recoveries budget, percentage of training budget, and percentage of recoveries budget as predictors. The Wald test shows that training budget, recoveries budget, and percentage of training budget were good predictors, making a significant contribution to prediction. The percentage of budget on recoveries was not a significant predictor. The Microfinance Banks should enhance the performance of non-prime household loans through capacity building to the borrowers and educate the borrowers on dangers of enforced loan recoveries. The government, through the Central Bank of Kenya, should have a training policy for the Microfinance Banks so that they can enlighten the borrowers on proper financial management to avoid conflicts with borrowers during loan recoveries.

A Novel Polyaxial Strength Criterion for Rock Materials Under General Stress Condition

2018 ◽  
Vol 10 (08) ◽  
pp. 1850082 ◽  
Author(s):  
Yugui Yang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Peijian Chen
Keyword(s):  
Stress State ◽  
Stress Condition ◽  
Strength Criterion ◽  
Friction Angle ◽  
External Loading ◽  
Nonlinear Characteristics ◽  
Rock Materials ◽  
Wide Range ◽  
Confining Pressures ◽  
The Relationship

Yielding or failure of rocks under the action of external loading is complicated due to the dependence on pressure sensitivity and Lode angle. In this study, a generalized hyperbolic strength criterion is proposed to describe the strong nonlinear characteristics of rocks over a wide range of confining pressures. The relationship between failure stress and instantaneous friction angle of rocks is analyzed based on nonlinear Mohr strength envelope. In order to reflect the influence of intermediate principal stress on the strength of rock materials, the generalized hyperbolic criterion has further been extended to complicated stress state. The failure criterion allows the possibility of transitions from an equilateral triangle to circle, which greatly improves the durability and applicability to describe the strength characteristics of various rocks under complicated stress state. The validity of the proposed criterion is verified by comparing predictions with experimental results of rocks.

Design method of a novel variable speed ratio line gear mechanism

2020 ◽  
pp. 095440622093772
Author(s):  
Yangzhi Chen ◽  
Xiaoping Xiao ◽  
Daoping Zhang ◽  
Haifei Xiao ◽  
Yueling Lyu
Keyword(s):  
Design Method ◽  
Speed Ratio ◽  
Variable Speed ◽  
Element Analysis ◽  
Constraint Equations ◽  
Order Curve ◽  
Contact Curve ◽  
Gear Mechanism ◽  
Parallel Axis ◽  
The Relationship

Based on the space curve meshing theory, a novel noncircular line gear mechanism was advanced, namely, this paper presented a design method of the variable speed ratio noncircular line gear with coplanar axes. Firstly, the universal contact curve equations of the constant speed ratio and variable speed ratio line teeth were established. After the constraint equations of the rotating angle of the driving and driven variable speed ratio noncircular line gears were analyzed and established, the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t in the VSR area was assumed to be a piecewise fourth-order curve. Then, the contact curve equations of the variable speed ratio noncircular line gears were derived, and the entity models of variable speed ratio noncircular line gears were built. The prototypes of the parallel axis and intersecting axis variable speed ratio noncircular line gears were manufactured by Stereo Lithography Apparatus, and the speed ratios were measured on the kinematic test rig. The kinematic and finite element analysis results demonstrate that the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t conforms to the designed function and the noncircular line teeth smoothly achieve the preset VSR transmission. The proposed design method is helpful to design the variable speed ratio noncircular line gears with lower theoretical sliding rate and wider variation range of the speed ratio; consequently, the designed variable speed ratio noncircular line gears have better applicability in specific variable speed ratio applications.

Investigation of Welded Joints Made of Construction Steel by the Barkhausen Noise Method

2020 ◽  
Vol 992 ◽  
pp. 957-963
Author(s):  
E. Nikolaeva ◽  
A. Nikolaev
Keyword(s):  
Stress State ◽  
Residual Stresses ◽  
Welded Joints ◽  
Arc Welding ◽  
Barkhausen Noise ◽  
Low Carbon ◽  
Butt Weld ◽  
Welded Structures ◽  
The Relationship ◽  
Weld Seams

Steel weld seams are characterized by heterogeneity of their microstructure. Microstructure affects the nature of the distribution, sign and magnitude of residual stresses. In combination with unfavorable factors (low temperature, metal hypoductility and an unsuccessful joint form) residual stresses lead to a decrease of load carrying capacity of a whole structure. In a weld seam residual stresses are distributed in a complex way and can affect the build quality of heavy section welded structures. Monitoring of residual stresses remains a big problem. Residual stresses in welds are often evaluated only by modeling. Unfortunately, all mathematical models describe the stress state of the welded material with low accuracy. Simple quality control, the results of which can be easy interpreted, is necessary. Welded joints made by manual arc welding and by automatic submerged arc welding were investigated. Butt seams of steel sheets of different thickness have been welded. Steel was low-carbon and low-alloyed. It is often used in welded structures for various purposes, including construction, and for pipelines manufacture. The temperature range of welded structures operation is very large – from-70 to 450С. The authors studied the structure of butt weld seams by the Barkhausen noise method, which is interesting as it represents an alternative to the known methods, which characterizes the structure and stress state of material. The relationship between the weld microstructure and magnetic noise is shown. Studies have allowed us to establish the relationship between the structure and magnetic properties and to evaluate the feasibility of applying the Barkhausen noise method to welded structures.

Passive vibration isolation of flexure jointed hexapod: A geometry design method

2020 ◽  
pp. 095440622095448
Author(s):  
Zongyu Zuo ◽  
Jiahao Wang ◽  
Heng Wang ◽  
Qiang Wang
Keyword(s):  
Vibration Isolation ◽  
Design Method ◽  
Sufficient Conditions ◽  
Disturbance Attenuation ◽  
Specific Kind ◽  
Design Algorithm ◽  
Geometry Design ◽  
Passive Vibration Isolation ◽  
The Relationship ◽  
Function Matrix

This paper presents the passive vibration isolation problem for a specific kind of Stewart Platform called flexure jointed hexapod (FJH). For purpose of analyzing the relationship between passive vibration isolation and parameters of the FJH, an existing dynamic model of the hexapod is re-cast appropriately to obtain the transfer function matrix from disturbance to generalized coordinates of the payload. Then, the system natural frequencies and the corresponding damping ratios are derived analytically. To guarantee the effective disturbance attenuation and isolation, a lower bound of the disturbance frequency with respect to the geometric parameters of the FJH is identified. Based on the identified sufficient conditions for disturbance isolation, a new design algorithm for geometry structure of the FJH and coefficients of the parallel spring-damping mechanism in struts is proposed. Finally, numerical simulation results are provided to demonstrate effectiveness of the proposed design algorithm.

Prediction of Creep Void Growth in Heat-Affected Zone of High Chromium Steel Weldments Considering Multiaxial Stress State

2012 ◽  
Author(s):  
Eiji Murakami ◽  
Masamitsu Hashimoto ◽  
Seiji Kikuhara
Keyword(s):  
Stress State ◽  
Heat Affected Zone ◽  
Void Growth ◽  
Stress Triaxiality ◽  
Chromium Steel ◽  
Growth Behavior ◽  
High Chromium ◽  
Multiaxial Stress State ◽  
The Relationship ◽  
Triaxiality Factor

This paper deals with a method for predicting creep void growth in heat-affected zone (HAZ) of high chromium steel weldments. The method has been proposed by authors based on the relationship between creep void density increasing rate and multiaxial stress state. In this study, internal pressure creep tests of ASME grade 91 (9Cr-1Mo-Nb-V) tubes with longitudinal weldments subjected to several internal pressures have been conducted to reveal creep void growth behavior in HAZ. In addition, finite element creep analyses of the specimens at different creep strain rates in base metal, weld metal and HAZ have been carried out to investigate distribution of stresses and stress triaxiality factor in HAZ. A comparison between stress distributions and void distributions revealed that stress triaxiality factor predominantly affects growth behavior of creep voids. From the result, the relationship between creep void density increasing rate and the parameter as a function of principal stress and triaxiality factor was established. It was found that there is a proportional relationship between creep void density increasing rate and the parameter to represent stress multiaxiality on the logarithmic graph. To verify proposed prediction method, the method was applied to the internal pressure creep test specimens at different experimental conditions. As a result, the predicted void distribution and void density increasing rates were in good agreement with experimental results.

Analysis of Fabric Deformation in a Roll-Making Operation Part III: Effect of Viscoelasticity

1992 ◽  
Vol 62 (11) ◽  
pp. 669-676 ◽  
Author(s):  
T. K. Ghosh ◽  
H. Peng ◽  
P. Banks-Lee
Keyword(s):  
Stress State ◽  
Stress Relaxation ◽  
Continuum Model ◽  
Present Model ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Plane Stress State ◽  
Numerical Examples ◽  
Fabric Deformation ◽  
The Relationship

The relationship between various parameters of roll making, fabric properties, and the resultant stresses developed within a fabric roll has been discussed in Parts I and II of this series. A discrete continuum model was used to describe fabric deformation during roll making. In the present model, the fabric is assumed to be in plane stress state and the effect in the filling direction is entirely neglected. The fabric is considered as anisotropic in warp and thickness directions. The effect of fabric viscoelasticity in the warp direction is also considered. A simple two-term Maxwell viscoelastic model is used to describe the fabric viscoelastic behavior. The stress relaxation process within fabric rolls during and after roll formation is discussed through numerical examples.

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