scholarly journals Probabilistic Modelling of Bending Strength of Timber Beams with the Help of Weak Zones Model

2021 ◽  
Author(s):  
Ireneusz Czmoch
Keyword(s):  
Random Field ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Point Load ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Weak Zones ◽  
Timber Beams

The variability of longitudinal bending strength of timber beams due to the presence of knots and other defects is analyzed. The weak zones model of timber beam bending strength used in the analysis consists of short weak zones (knots or group of them) and strong sections of clear wood. The load bearing capacity of timber beams is defined as an extreme (minimum) value problem or as a first downcrossing problem. Assuming a marked Poisson random field with zero correlation between all random variables, cumulative probability distribution functions of the load carrying capacity of timber beams were determined by analytical methods for typical load cases: pure bending, midspan point load and one-third point load. These results, as well as the marked Poisson random field as a model of longitudinal variability of the bending strength of timber beams, can be applied in the reliability analysis of timber structures. Furthermore, the analytical formulae for the cumulative distribution functions of load carrying capacity of timber beams can provide a good reference for numerical analysis conducted with Monte Carlo simulation to determined statistics for specific timber members.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

The Elastic-Softening Failure of Floating Beams

1988 ◽  
Vol 32 (01) ◽  
pp. 37-43
Author(s):  
Paul C. Xirouchakis
Keyword(s):  
Carrying Capacity ◽  
Maximum Load ◽  
Point Load ◽  
Negative Stiffness ◽  
Load Carrying Capacity ◽  
Perfectly Plastic ◽  
Load Carrying ◽  
Elastic Perfectly Plastic ◽  
The Moment ◽  
Elastic Softening

The solution is presented for an infinite elastic-softening floating beam under a point load. The response depends on two nondimensional parameters: the negative stiffness coefficient that characterizes the descending part of the moment-curvature curve, and the nondimensional softening region half-length. The solution exhibits two important features that the elastic-perfectly plastic solution does not show. First, in certain ranges of parameters, the elastic-softening beam has a clearly defined maximum load carrying capacity. Second, in some other ranges of parameters, the elastic-softening beam has a minimum load or residual strength. The beam stiffens up upon further deformation due to the reactions of the water foundation. Critical softening parameters are calculated that separate stable from unstable behavior.

Influence of the Case Properties After Nitriding on the Load Carrying Capacity of Highly Loaded Gears

2019 ◽  
Author(s):  
André Sitzmann ◽  
Thomas Tobie ◽  
Karsten Stahl ◽  
Stefan Schurer
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Cost Savings ◽  
High Hardness ◽  
Compound Layer ◽  
Alloy Element ◽  
Case Hardening ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Highly Loaded

Abstract The load carrying capacity of highly loaded gears can be increased by thermochemical surface treatments such as nitriding or case hardening. In contrast to case hardening, the nitriding treatment is carried out at lower process temperatures and therefore creates lower distortion. As a result, grinding after nitriding is usually not necessary. Nitrided gears are ordinarily characterized by a thin, high-hardness, a few micrometers thick compound layer of iron and alloy element nitrides directly on the surface and a subsequent diffusion layer reaching more deeply into the material. Nitriding, therefore, provides an alternative to case hardening for distortion-sensitive components and offers potential for cost savings in the production of highly loaded gears. This publication will focus on the influence of nitriding on the load carrying capacity of highly loaded gears. In addition, this paper summarizes the current state of knowledge of nitrided gears and gives an insight into current research in the field of nitrided gears. In particular, the influence of the compound layer on the tooth root bending strength and the flank load carrying capacity achieved within the research project FVA 386 II is discussed.

scholarly journals Performance of Sprayed Fiber Reinforced Polymer Strengthened Timber Beams

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
S. Talukdar ◽  
N. Banthia
Keyword(s):  
Energy Absorption ◽  
Carrying Capacity ◽  
Absorption Capacity ◽  
Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Fiber Reinforced ◽  
Bonding Agents ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
Timber Beams

A study was carried out to investigate the use of Sprayed Fiber Reinforced Polymer (SFRP) for retrofit of timber beams. A total of 10-full scale specimens were tested. Two different timber preservatives and two different bonding agents were investigated. Strengthening was characterized using load deflection diagrams. Results indicate that it is possible to enhance load-carrying capacity and energy absorption characteristics using the technique of SFRP. Of the two types of preservatives investigated, the technique appears to be more effective for the case of creosote-treated specimens, where up to a 51% improvement in load-carrying capacity and a 460% increase in the energy absorption capacity were noted. Effectiveness of the bonding agent used was dependent on the type of preservative the specimen had been treated with.

Uniform Loading Analysis for Pin-Hole-Output Mechanism of FA Cycloid Drive

2012 ◽  
Vol 479-481 ◽  
pp. 925-931
Author(s):  
Lei Lei ◽  
Ying Tao ◽  
Tian Min Guan
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Deformation Analysis ◽  
Load Carrying Capacity ◽  
Bending Stress ◽  
Uniform Loading ◽  
Force Loading ◽  
Load Carrying ◽  
Stress And Deformation ◽  
Loading Analysis

In order to balance the force loading on the dowel pin , improve the load carrying capacity on pin-hole type output mechanism the FA cycloid drive, we considered to add uniform loading ring on the cantilever end of the pins in this paper. Under the action of uniform loading ring, we did the stress and deformation analysis on the dowel pin; Through the examples comparison we found that, the maximum bending stress of the dowel pin is reduced by 77.86% after adding the uniform loading ring, the dowel pin stress is well-distributed, and the bending strength of output mechanism is improved, thus the load carrying capacity of overall unit is improved.

scholarly journals Deep nitriding—contact and bending strength of gears with increased nitriding hardening depth

2021 ◽  
Author(s):  
André Sitzmann ◽  
Stefanie Hoja ◽  
Stefan Schurer ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Experimental Investigations ◽  
Case Hardening ◽  
Load Carrying Capacity ◽  
Industrial Practice ◽  
Aerospace Applications ◽  
Upper Limit ◽  
Load Carrying ◽  
High Fatigue

AbstractThe load carrying capacity of gears can be significantly increased by nitriding. However, the required nitriding hardening depth depends on the stress level and the gear size. In order to achive a high fatigue resistance and durability of nitrided gears an adequate nitriding hardening depth is necessary. In industrial practice, a nitriding hardening depth (NHD) of about 0.6 mm is currently regarded as the upper limit that can be reached within a reasonable time and cost. This also limits of the load carrying capacity of nitrided gears, in particular with increasing gear sizes. Therefore, case hardening is the main treatment used with increasing gear sizes, although nitriding provides some advantages over case hardening. However, with an increased nitriding hardening depth, a significant increase in the load carrying capacity of nitrided gears for medium and larger gear sizes could be expected, which will be discussed in this publication. In order to evaluate the expected potential of the load carrying capacity of nitrided gears with an increased nitriding hardening depth of NHD ≈ 0.8 to 1.0 mm (deep nitriding heat treatment) made out of the materials 31CrMoV9 (1.8519), 30CrNiMo8 (1.6580) and 32CDV13 (alloy for aerospace applications according to AIR 9160), experimental investigations were carried out, which will be discussed in this publication. Both, the tooth root bending strength and the flank load carrying capacity were investigated.

scholarly journals Experimental Work on Using Fully Wrapped Post-Tensioned Metal Straps Around Normal Steel Reinforced Beams to Increase Flexural Strength of R.C Beams

2021 ◽  
Vol 8 (1) ◽  
pp. 50-62
Author(s):  
Wrya Abdullah ◽  
◽  
Avesta Omer ◽  
Serwan Rafiq
Keyword(s):  
Flexural Strength ◽  
Carrying Capacity ◽  
Point Load ◽  
Load Carrying Capacity ◽  
Load Testing ◽  
Reinforced Beams ◽  
Load Carrying ◽  
Tensile Zone ◽  
Main Factor ◽  
Post Tensioned

To increase the capacity load carrying of the beams, post tensioned metal straps are fully wrapped around the beams in their tensile zone in this study. In total four normal R.C beams with the depth of 160 mm, height of 240 mm and total length of 2100 mm are cast and tested under four-point load testing. The number of variables is kept to minimum of two which are the number and location of the straps. It is found that using post tensioned metal straps fully wrapped around the beams can increase the load-carrying capacity of the beams by 36% at least and 39% at a max. The main factor in influencing the rate is the location of the straps. A complete guide on using the material along with its application on the beams are explicitly described in the paper.

scholarly journals Tooth Root Bending Strength of Gears: Dimensional Effect for Small Gears Having a Module below 5 mm

2021 ◽  
Vol 11 (5) ◽  
pp. 2416
Author(s):  
Franco Concli
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Size Factor ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Gear Design ◽  
Industrial Sectors ◽  
Load Carrying ◽  
European Standards ◽  
Design Effectiveness

Downsizing is a more and more widespread trend in many industrial sectors, and, among the others, the automotive industry is pushing the design of its components towards increasingly compact, lightweight, efficient, and reliable solutions. In the past, the drivetrains for automotive were designed and manufactured with gears having modules in the range 3 to 10. In this respect, the main actual European standards for gear design such as ISO 6336:2019 (based on the DIN 3990:1987) are validated in the 3 to 10 mm range only. Moreover, it is well known that, by increasing the gear size, the gear size factor for tooth bending YX reduces. However, nowadays the advances in terms of materials and design knowledge have made possible the realization of miniaturized gearboxes with gears having normal modules below 3 mm with comparable (or better) reliability. In this scenario, understanding how the size affects (positively) the load-carrying capacity for tooth root bending for small modules below 5 mm is fundamental to maximize the design effectiveness in case of downsizing of the drivetrains. In this paper an experimental study was performed on small gears made of 39NiCrMo3 having a normal module of 2 mm to verify the load-carrying capacity for tooth root bending. Based on the experimental evidences and additional data from literature and past studies by the author, an extended formula for the size factor YX (according to ISO 6336) is proposed.

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

Fuzzy Sets Theory in Comparison with Stochastic Methods to Analyse Nonlinear Behaviour of a Steel Member under Compression

2005 ◽  
Vol 10 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Z. Kala
Keyword(s):  
Fuzzy Sets ◽  
Carrying Capacity ◽  
Stochastic Methods ◽  
Nonlinear Behaviour ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Input Parameters ◽  
Stochastic Solution ◽  
Fuzzy Solution ◽  
Sets Theory

The load-carrying capacity of the member with imperfections under axial compression is analysed in the present paper. The study is divided into two parts: (i) in the first one, the input parameters are considered to be random numbers (with distribution of probability functions obtained from experimental results and/or tolerance standard), while (ii) in the other one, the input parameters are considered to be fuzzy numbers (with membership functions). The load-carrying capacity was calculated by geometrical nonlinear solution of a beam by means of the finite element method. In the case (ii), the membership function was determined by applying the fuzzy sets, whereas in the case (i), the distribution probability function of load-carrying capacity was determined. For (i) stochastic solution, the numerical simulation Monte Carlo method was applied, whereas for (ii) fuzzy solution, the method of the so-called α cuts was applied. The design load-carrying capacity was determined according to the EC3 and EN1990 standards. The results of the fuzzy, stochastic and deterministic analyses are compared in the concluding part of the paper.

Sign in / Sign up

Export Citation Format

Share Document