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The purpose of this paper is to focus on the influences of residual stresses which were induced during roll-forming sections on lateral-torsional buckling of thin-walled cold-formed steel channel and built-up I-sections beams. Built-up I section is made up of two back-to-back cold-formed channel beams. In this direction, at the primary stage, the roll-forming process of a channel section was simulated in ABAQUS environment and the accuracy of the result was verified with those existing experiments. Residual stresses and strains in both longitudinal and circumferential transverse directions were extracted and considered in the lateral-torsional buckling analysis under uniform end moments. The contribution of the current research is devoted to the numerical simulation of the rolling process in ABAQUS software enabling to restore the remaining stresses and strains for the buckling analysis in the identical software. The results showed that the residual stresses decrease considerably the lateral-torsional buckling strength as they have a major impact on short-span beams for channel sections and larger span for built-up I sections. The obtained moment capacity from the buckling analysis was compared to the predictions by American Iron and Steel Institute design code and it is found to be conservative.

This paper has explained a numerical study on the roll-forming process of a channel section and member moment capacities related to the lateral-torsional buckling of the rolled form channel and built-up I-sections beams under uniform bending about its major axis. It has also investigated the effects of residual stresses and strains on the behaviour of this buckling mode.

The residuals decrease the moment capacities of the channel beams and have major effect on shorter spans and also increase the local buckling strength of compression flange. But the residuals have major effect on larger spans for built-up I sections. It could be seen that the ratio of moment (with residuals and without residuals) for singly symmetric sections is more pronounced than doubly symmetric sections. So it is recommended to use doubly symmetric section of cold-formed section beams.

The incorporation of residual stresses and strains in the process of numerical simulation of rolled forming of cold-formed steel sections under end moments is the main contribution of the current work. The effect of residual stresses and strains on the lateral-torsional buckling is, for the first time, addressed in the paper.

The natural frequency of a diaphragm with residual stress in contact with a liquid is investigated theoretically in this paper. The paper aims to discuss these issues.

An analytical calculation using the nondimensional added virtual mass incremental (NAVMI) factors is performed to find the dependency of the natural frequency on the residual stress when the diaphragm vibrating in contact with a liquid.

The analysis gives the residual stress contribution to the added virtual mass.

The magnitude of the added virtual mass depends on the residual stress. However, the magnitude of the natural frequency is found to be insignificant to the residual stress.

Selective laser melting (SLM) is a promising additive manufacturing technology in the field of complex parts’ fabrication. High temperature gradient and residual stress are vital problems for the development of SLM technology. The purpose of this paper is to investigate the influence of substrate characteristics on the residual stress of SLMed Inconel 718 (IN718).

The SLMed IN718 samples were fabricated on the substrates with different characteristics, including pre-compression stress, materials and pre-heating. The residual stress at the center of the top surface was measured and compared through Vickers micro-indentation.

The results indicate that the residual stress reduces when the substrate contains pre-compression stress before the SLM process starts. Both substrate thermal expansion coefficient and thermal conductivity affect the residual stress. In addition to reducing the difference of thermal expansion coefficient between the substrate and the deposited material, the substrate with low thermal conductivity can also decrease the residual stress. Substrate pre-heating at 150°C reduces nearly 42.6 per cent residual stress because of the reduction of the temperature gradient.

The influence of substrate characteristics on the residual stress has been studied. The investigation results can help to control the residual stress generated in SLM processing.

The bodies of aircraft structures have a lot of fastener holes and under different situations these holes bear external forces, which cause a tensile stress on the surface that leads to the failure of materials. Cold expansion process is one of the widely‐used methods to improve the fatigue behavior of materials used in aerospace industry, and such improvement is due to the compressive residual stress around cold expanded hole. The induced residual stress distribution around cold expanded hole is affected by several parameters such as, diametrical interfaces, surface finish of fastener holes, temperature, mandrel speed, i.e. the speed of inserting mandrel into the hole, and so on. In previous studies, most of effective parameters were investigated, whereas, the effect of mandrel speed on the residual stress distribution has not been considered. The present study, seeks to simulate cold expansion process on aluminum alloy 2A12TA using ABAQUS finite element (FE) package and to consider the effect of different mandrel speeds on residual stress distribution around cold expanded hole. It aims to verify the results of FE simulation by experimental data.

There are two kinds of data in this paper; experimental and FE results. The experimental results for cold expansion process have been extracted from the literature and ABAQUS finite element package was employed in order to simulate the above‐mentioned process. Moreover, FE results were validated by the experiments.

The results presented here show the influence of mandrel speed on residual stress distribution around cold expanded hole using a new analytical‐numerical method. The results gained by FE simulation show relative differences between the diagrams of residual stress distribution corresponding different mandrel speeds. It is shown in the paper; the residual stress around cold expanded hole rises by the increase of mandrel speed and consequently the improvement of fatigue life will be achieved.

The present study is part of Abbas Hosseini's MSc. dissertation, an original research work.

The purpose of this paper is to devise a robust statistical process control methodology that will enable service managers to better monitor the performance of correlated service measures.

A residuals control chart methodology based on least absolute value regression (LAV) is developed and its performance is compared to a traditional control chart methodology that is based on ordinary least squares (OLS) regression. Sensitivity analysis from the goal programming formulation of the LAV model is also performed. The methodology is applied in an actual service setting.

The LAV based residuals control chart outperformed the OLS based residuals control chart in identifying out of control observations. The LAV methodology was also less sensitive to outliers than the OLS approach.

The findings from this study suggest that the proposed LAV based approach is a more robust statistical process control method than the OLS approach. In addition, the goal program formulation of the LAV regression model permits sensitivity analysis whereas the OLS approach does not.

This paper shows that compared to the traditional OLS based control chart, the LAV based residuals chart may be better suited to actual service settings in which normality requirements are not met and the amount of data is limited.

This paper is the first study to use a least absolute value regression model to develop a residuals control chart for monitoring service data. The proposed LAV methodology can help service managers to do a better job monitoring related performance metrics as part of a quality improvement program such as six sigma.

This paper gives a bibliographical review of the finite element methods (FEMs) applied to the analysis of ceramics and glass materials. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1977‐1998. The following topics are included: ceramics – material and mechanical properties in general, ceramic coatings and joining problems, ceramic composites, ferrites, piezoceramics, ceramic tools and machining, material processing simulations, fracture mechanics and damage, applications of ceramic/composites in engineering; glass – material and mechanical properties in general, glass fiber composites, material processing simulations, fracture mechanics and damage, and applications of glasses in engineering.

This article deals with how to test for and evaluate interdependence among control practices in a management control system using structural equation modeling. Empirical research on the levers of control (LOC) framework is used as an example. In LOC research, a path model approach to interdependence has been developed. The appropriateness of this approach is evaluated, developed, and compared with the correlation of residuals approach (seemingly unrelated regression) implemented in the wider complementarity literature. Empirical examples of the different models are shown and compared by using a data set on LOC of 120 SBUs in Sweden. The empirical results show that modeling interdependence among control practices in a management control system as non-recursive (bi-directional) paths or as residual correlations evidently affects the conclusions drawn about interdependence in terms of both presence and magnitude. The two models imply different views on how to conceptualize interdependence and are not statistically and empirically comparable. If using non-recursive path models, several model specification issues appear. To be able to identify such models, this needs to be carefully considered in the theory and research design prior to data collection.

The purpose of this paper is to investigate whether CEO compensation scheme may induce some agency conflicts in the foreign exchange risk hedging policy.

Residual exposure is a post-hedging variable computed as the ratio of unrealized foreign exchange risk gains/losses to international sales. The authors follow the optimal hedging theory developed by Smith and Stulz (1985). The residual foreign exchange risk exposure is a way to capture some consequences of the managerial risk aversion, whereas the compensation scheme granted to CEO reveals that of the shareholders. The authors interpret any deviation to the predictions of this theory as a mark that some agency conflicts exist.

CEO compensation (stock-options, shares and so) significantly influence the level of the residual foreign exchange risk exposure. Both in-the-money exercisable options and shares are negatively related to the residual exposure of foreign exchange risk. The authors also document that the effect of agency problems is rather contingent because shares and options have especially a negative impact when the level of foreign exchange risk is relatively high.

The residual FX risk exposure variable the authors promote in this paper completes the traditional proxies used to depict the corporate hedging policy such as the nominal or total fair value of currency derivatives (Davies et al., 2006), use of nominal values (Spanò, 2007), use of fair values of derivatives and the fraction of production hedged (Wang and Fan, 2011). The information that it conveys differs significantly from the one provided by traditional proxies because it captures the year-end post hedging firm’s risk profile.

The purpose of this paper is to clarify the effect of material hardening model and lump-pass method on the thermal-elastic-plastic (TEP) finite element (FE) simulation of residual stress induced by multi-pass welding of materials with cyclic plasticity.

Nickel-base alloy and stainless steel, which are used in J-type weld for manufacturing the nuclear reactor pressure head, can easily harden during multi-pass welding. The J-weld welding experiment is carried out and the temperature cycle and residual stress are measured to validate the TEP simulation. Thermal-mechanical sequence coupling method is employed to get the welding residual stress. The lumped-pass model and pass-by-pass FE model are built and two materials hardening models, kinematic hardening model and mixed hardening model, are adopted during the simulations. The effects of material hardening models and lumped-pass method on the residual stress in J-weld are distinguished.

Based on the kinematic hardening model, the stresses simulated with the lumped-pass FE model are almost consistent with those obtained by the pass-by-pass FE model; while with the mixed hardening material model, the lumped-pass method has great effect on the simulated stress.

A computation with mixed isotropic-kinematic material seems not to be the appropriate solution when using the lumped-pass method to save the computation time.

In the simulation of multi-pass welding residual stress involved in materials with cyclic plasticity, the material hardening model should be carefully considered. The kinematic hardening model with lump-pass FE model can be used to get better simulation results with less computation time. The results give a direction for welding residual stress simulation for the large structure such as the reactor pressure vessel.

This paper aims to present a mathematical model of predicting the residual moment capacity of fire-damaged reinforced concrete (RC) elements after cooling to ambient temperature which also reflects the role of bond between steel rebar and surrounding concrete.

The prediction of residual moment capacity of fire-damaged RC element has been carried out for two scenarios: by assuming perfect bond between surrounding concrete and steel rebar after fire exposure and by incorporating a relative slip between surrounding concrete and steel rebar and hence assuming partial bond between them after fire scenario. The predicted results are then compared with the experimental results available in different literatures.

It is found that on comparison between the predicted results and the experimental results, the proposed mathematical prediction model, when bond-characteristics are considered, shows better agreement with the experimental results as compared with those by conventional method with perfect bond assumption.

The constitutive relationship for thermal residual properties of steel rebar and concrete has been used in the proposed prediction model along with relative slip approach between surrounding concrete and steel rebar after fire scenario and consequently to predict the residual moment capacity of the fire-damaged RC element after cooling.