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The purpose of this paper is to introduce a high-speed rolling bearing test rig supported by sliding bearing and its first experimental results.

Through analyzing the disadvantages of using rolling bearing as supporting bearing, the bottlenecks that need to be resolved urgently in the development of rolling bearing experimental technology, and the advantages of the sliding bearing, this study used the sliding bearing as the supporting bearing for the high-speed rolling bearing test rig for the purpose of prolonging the service life, increasing the load capacity and promoting the operating stability.

The experimental results show that the high-speed rolling bearing test rig supported by sliding bearing could stably rotate at 70,800 rpm without installing the test bearing; the temperature of the sliding bearing is increasing with the rotating speed and the maximum is less than 95°C. Moreover, the new test rig, installing an angular contact ball bearing as test bearing, could also stably rotate at 54,000 rpm with 2 kN axial load and 1 kN radial load; the temperature of the sliding bearing is increasing with the rotating speed and the maximum temperature is less than 97°C.

Rolling test rig has been established.

This paper proposes a high-speed rolling bearing test rig supported by sliding bearing, which greatly prolongs the service life, increases the load capacity and promotes the operating stability, moreover, reduces the risk of supporting bearing failure before the test bearing. This paper can also provide a new idea and reference for the design of similar bearing test rig.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0085/

This paper aims to examine the effect of ownership structure and board gender diversity on charitable donations for a group of listed electronics companies in Taiwan.

Using linear regression analysis, this paper analyses the ownership structure, board gender diversity and charitable donations of 380 Taiwanese electronics companies (2011-2013).

While domestic institutional investors, such as domestic mutual funds and corporate investors, take more of agency logic view, it negatively impacts on charitable donations. However, the empirical findings of this paper indicate that board gender diversity with the critical number of female directors was positively related to charitable donation. Thus, it is clear that female directors reaching critical numbers were taking more of a stakeholder view of institutional logic, emphasizing the balance of interests of internal and external stakeholders.

This paper is limited to selected Taiwanese electronics companies over a two-year time frame, and charitable donations are the only proxy of corporate social responsibility (CSR) activity. The paper suggests that, as predicted by stakeholder theory and critical mass theory, companies with boards composed of at least three female directors make higher charitable donations.

This paper indicates that female directors on the board should have more voices on the board regarding the necessity and importance of CSR.

The paper contributes to existing literature by looking into the effects of ownership structure and board gender diversity on charitable donations.

The purpose of this paper is to introduce the structure design process of the cantilever spindle with limited installation space and wishing to increase its critical speed.

In this paper, the finite element method was used to analyze the influence of the supporting stiffness and the structure of the spindle on the critical speed, and then the structure of the spindle was designed; moreover, the experiment was accomplished and the experiment results show that the spindle can work stably.

Through analyzing the influence of the supporting stiffness and the structure of the spindle on the critical speed, the following conclusions could be obtained: the shape of the first-mode is the bend vibration of the cantilever of the spindle; the first-order critical speed of the spindle gradually decreases with the diameter and length of the cantilever increasing; the first-order critical speed of the spindle increases with the depth and diameter of the blind hole increasing; and the experiment was accomplished and the experiment results show that the spindle can work stably.

In this paper, the finite element method was used to design the spindle of the testing machine, and satisfactory results were obtained. It can provide a theoretical reference for the design of a similar spindle.

The purpose of this study is to develop a normal contact stiffness (NCS) model among three disks of the assembled rotor system, which systematically considers the friction coefficient, the asperities interaction and the elastoplastic contact regime.

Based on the revised fractal theory, considering the friction effect, the elastoplastic contact regime and the asperities interaction in a simple way, the total NCS among three disks of the rod-fastening rotor bearing system is established. Effects of fractal dimension and roughness, friction coefficient, asperities interaction and material properties on the normal stiffness are investigated by simulations and the relevant comparisons are given for examining the reasonability of the proposed model.

NCS will decrease when asperities interaction and friction are included. As the load increases, the influences of asperities interaction and friction on stiffness become serious. NCS will be enhanced when the elastoplastic regime is considered.

A comprehensive NCS model is developed. It provides a theoretical basis for the modeling of the NCS for multi-interfaces.

The purpose of this study is to investigate the dynamic behavior of the ball bearing with cage broken.

By analyzing the complicated relationship and interactions among the ball bearing elements, the dynamic modelling of the ball bearing with broken cage was established, and the dynamic simulations were conducted by solving the ball bearing dynamic equations using varying-step Runge–Kutta integration.

The computational results show that there is considerable distinguishment in the dynamic characteristics between the normal cage and the broken cage of the bears. The broken cage makes the trajectory of the cage erratic, and the vibration amplitude is much bigger than that of the normal cage, which makes the motion of the cage unstable. When one of the cage lintels breaks up, the two adjacent balls will collide with each other; what is worse, this may make the balls crush because of the high amplitude of the collision force. The broken cage makes the cage-race interaction force much larger than that of the normal cage, which could promote the guiding ring and quicken the cage wear-failure.

This study can provide important ideas for the fault identification of the ball bearing with cage broken.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0042/

Small firms in China anticipate entrepreneurial opportunities for continual growth. However, they may fail to recognize opportunities because of their inefficiency in managing their knowledge.

In this explorative paper, the authors assess the opportunity recognition efficiency of 168 small Chinese firms using data envelopment analysis (DEA). Supplementary Tobit regressions were conducted for further exploring the factors that influence the firms’ efficiency in opportunity recognition.

Results from the DEA suggest that most respondents recognize significantly fewer opportunities than those with equivalent knowledge stock. Moreover, many firms have low levels of pure technical efficiency but high levels of scale efficiency, indicating insufficient use of knowledge as a major reason for inefficiency in opportunity recognition. The Tobit regressions show that sales and research and development intensity are relevant to a firm’s opportunity recognition efficiency.

This study calls for the investigation of efficiency issues in opportunity recognition and suggests that managers guard against unwarranted loss of opportunities owing to inefficient use of existing knowledge elements.

First, the authors introduce the concept of opportunity recognition efficiency within the entrepreneurial process. Second, they manifest the role of knowledge management in opportunity recognition. Third, they introduce DEA to investigate the relationship between knowledge stock and opportunity recognition. Fourth, this study reveals that inefficient use of knowledge is a disadvantage of small Chinese firms in terms of opportunity recognition.

This study aims to investigate whether and how public air environmental concern (PAEC) affects corporate environmental, social and governance (ESG) performance in emerging markets.

This study measured PAEC using the Baidu index search keyword “雾霾 (PM2.5)” and assessed its impact on corporate ESG among Chinese A-share listed companies from 2011 to 2020 through regression analysis.

The empirical results indicate a positive relationship between PAEC and corporate ESG. Moreover, PAEC facilitates enhanced corporate ESG performance by mediating through corporate reputation and government environmental regulations. Heterogeneity analysis shows that the promotion effect of PAEC on ESG is more pronounced in the subgroups of companies with an excellent green image, low perceived uncertainty, strong management political connections, low short-termism, high industry technological levels and low pollution levels.

The practical implications of this study underscore the importance for policymakers, investors and companies to prioritize PAEC and its influence on corporate ESG performance.

This study contributes to ESG literature by highlighting the positive impact of external oversight, such as PAEC.

Asymmetric rotating machinery supported by oil film bearings is relatively common in practical applications. The purpose of this study is to propose a method for estimating the oil film parameters of the bearings in an asymmetric rotor-bearing system.

The proposed method requires the finite element model and translational displacement responses at the center of mass and bearings locations to form a regression equation to estimate the unknown parameters. Due to the transverse stiffness of the asymmetric rotor is not symmetrical, the analysis and parameter estimation procedures are performed in a rotating coordinate. Numerical simulations were carried out to illustrate the vibration characteristics of the asymmetric rotor system. The proposed method is applied to the simulated responses to estimate the assumed oil film parameters. The influence of the estimated parameter deviations on the rotor dynamic characteristics is discussed.

The vibration characteristics of asymmetric rotors are different from those of symmetrical rotors. The bearing parameters estimated by the proposed method are close to the assumed values, within a maximum error of 9%. The deviations of the estimated parameters have little effect on the vibration characteristic of the rotor system.

The proposed method does not require changing the rotational speed or applying additional excitation force to the rotor, which is suitable for the field test.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2023-0111/

The purpose of this study is to present a numerical model for scratched tilting-pad bearings (STPBs) with nonuniform grids. In addition, the model is used to reveal the effects of the structural parameters of bearings on the dynamic characteristics of STPBs under impact loading.

By combining the Reynolds equation, the flow balance equation and the assumption of adiabatic bearings and shafts, a thermo-hydrodynamic model with nonuniform grids of scratched journal bearings was built. Describing the motion of the shaft using the Euler method and introducing the pad-tilting-angle modification equation, a dynamic model of STPBs was established.

The occurrence of scratches in tilting-pad bearings yields great sensitivity to impact loading. Less width-to-diameter ratio and larger clearance ratio reduce the minimum film thickness and enlarge the maximum film pressure, which may lead to bearing collision or abrasion. Moreover, STPBs with larger clearance ratios take longer to recover from impact loading.

This work is original and a valuable reference for the analysis of the dynamic characteristics of STPBs. The effects of other factors on the dynamic characteristics of STPBs can be further investigated based on this model.

This study aims to obtain the dynamic behaviours of cracked rod-fastening rotor bearing system (RFBS), and experimental investigation was carried out to examine the dynamic characteristics of this kind of assembled rotor bearing system with a transverse crack passing through the critical speed.

An experimental test rig of cracked RFBS was established for examining the vibration behaviours between intact and cracked system. The crack on the surface of a fastening rod was simulated by wire-electrode cutting processing method. The comprehensive analysis method of vibration was used to obtain the dynamic characteristics such as vibration amplitude, acceleration and whirling orbits before and after the critical speed as well as the instantaneous response in the process of speed up.

Some experimental vibration datum is obtained for cracked RFBS. The appearance of a crack will introduce the initial bending and make the vibration amplitude, acceleration and instant response in the process of speed up increase greatly as well as the change of whirling orbits.

The actual vibration characteristics for this complex assembled rotor system with a transverse crack are given passing through the critical speed. It can provide some useful help for monitoring the vibration behaviours of this kind of assembled rotor system as well as the detection of the crack fault.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0260/