Rheological behavior of acylated pepsin-solubilized collagen solutions: Effects of concentration

Conghu Li,Lian Duan,Zhenhua Tian,Wentao Liu,Guoying Li,Xiaoping Huang 한국유변학회 2015 Korea-Australia rheology journal Vol.27 No.4

Effects of concentration on the rheological behavior of acylated pepsin-solubilized collagen solutions were investigated by steady shear tests, dynamic frequency sweep, creep tests and thixotropic loop measurements in this paper. The results showed that both acylated collagen and native collagen solutions exhibited the typical pseudoplastic behavior and displayed shear thinned behavior with the increase of shear rate. With the increase of acylated collagen concentrations from 5 to 10 mg/mL, shear viscosity, elasticity modulus (G'), viscous modulus (G''), complex viscosity (η*), and the ability to resist deformation increased due to the physical entanglement, whilst loss tangent (tan δ) decreased. Additionally, with the increase of acylated collagen concentrations, the area of thixotropic loop increased from 6.94 to 44.40 watts/m3, indicating that the thixotropy of acylated collagen increased. Compared with native collagen solution, acylated collagen solution had stronger shear viscosity, η*, thixotropy, and ability to resist deformation. Furthermore, Power law model, Carreau model, Cross model, Leonov model and Burger model, were suitable for the fitting of the experimental data

Energy Efficiency and Dynamic Analysis of a Novel Hydraulic System with Double Actuator

Mengdi Gao,Lei Li,Qingyang Wang,Conghu Liu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3

At present, increased attention has been given to energy effi ciency promotion and energy saving of manufacturing equipment and systems. Hydraulic system is widely used in engineering machinery industries; however, the high energy consumption and low energy effi ciency of which limit its development and application. On the basis of previous research on hydraulic system, an energy-effi cient hydraulic system with double actuator is proposed in this study. This hydraulic system can reduce the energy consumption by reusing the potential energy loss of the system. In this novel hydraulic system, the chambers of two actuators are connected with rod by pipes and valves. During the operating processes, the falling operation of one cylinder and the returning operation of the other are synchronized. That is, one actuator remains at the top point performing the demanded operation, whereas the other one remains at the bottom performing the corresponding operation. System models are developed to address the energy consumption and dynamic performance of the proposed hydraulic system. This hydraulic system is applied into a press to study its energy-saving mechanism and dynamic performance during transient under various working conditions. On the basis of the simulation and experimental results, energy and production effi ciency are compared and discussed. Results show that in comparison with the energy and time consumption of the original 630 kN hydraulic press, the energy-saving potential has reached 17.34%, and the production effi ciency can be improved by 18.85%.

Task-oriented energy benchmark of machining systems for energy-efficient production

Wei Cai,Li Li,Shun Jia,Conghu Liu,Jun Xie,Luoke Hu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.1

The energy benchmark has been recognised as an effective analytical methodology and management tool that help to improve the efficiency and performance of energy utilisation. With a wide distribution and large amount of energy consumption at a low efficiency, machining systems have considerable energy-saving potential. This paper proposes a task-oriented energy benchmark in machining systems, and illustrates the concept of the task-oriented energy benchmark and indicators. A method for developing the task-oriented energy benchmark considering the certainty production task and the uncertainty production task is proposed, which lays a solid foundation for studying the energy benchmark, benchmark rating system and energy certification. Furthermore, a case study of the task-oriented energy benchmark not only verifies the reliability but the effectiveness for energy-efficient production.

A Review on Energy Consumption and Efficiency of Selective Laser Melting Considering Support: Advances and Prospects

Qingyang Wang,Mengdi Gao,Qiang Li,Conghu Liu,Lei Li,Xinyu Li,Zhifeng Liu 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1

Selective laser melting (SLM) exhibits excellent manufacturing accuracy and forming ability. However, the laser beam layering process is characterized by high specific energy consumption, long manufacturing cycle, and low energy efficiency. The use of supports increases the SLM building quality and eliminates defects caused by thermal and residual stresses; however, an improper support structural design increases the process energy consumption for manufactured parts. To control energy consumption and building quality during SLM, this study first discusses the main challenges related to energy saving and improving the building quality by performing an energy consumption analysis, process energy consumption optimization, and supporting structure optimization. The obtained results reveal that it is difficult to achieve high building quality only by controlling the process parameters and energy consumption by the SLM equipment. Next, the effect of supporting structures on the process energy consumption is examined to enable the construction of an SLM energy consumption model that considers the presence of supports. Finally, the effect of supports on the building quality is elucidated by studying the influence of supporting structures on thermal and residual stresses. By identifying the most energy-efficient support, the process energy efficiency and building quality may be simultaneously optimized. The proposed method represents a new approach to reducing energy consumption and improving the building quality during SLM. This study establishes a theoretical foundation for the subsequent industrial applications, providing a thorough literature review and describing the existing challenges in the SLM manufacturing field.

Analysis and Optimization of Energy Consumption for Multi-part Printing Using Selective Laser Melting and Considering the Support Structure

Zhilin Ma,Mengdi Gao,Kai Guo,Qingyang Wang,Lei Li,Conghu Liu,Guang Zhu,Zhifeng Liu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.3

Selective laser melting (SLM) can form complex and precise metal parts simultaneously and is widely used in medical and aerospace fields. The support structure plays an important role in SLM process, including supporting the overhanging structure, dissipating heat, and minimizing geometric deformation caused by internal stress. However, a non-optimal support structure causes increased energy and material consumption during processing and must be removed afterward to allow for utilization of the parts. Existing support structure design methods only consider reducing the support of a single part, and research on the support and energy consumption of simultaneous multi-part printing is lacking. Therefore, to reduce the energy and material consumption of simultaneous multi-part printing by SLM and improve processing efficiency, an energy consumption analysis and optimization method is proposed in this study from the perspective of the support structure. Based on previous studies on energy consumption distribution of the additive manufacturing process, a multi-component SLM energy consumption and material consumption model was established. Furthermore, a shared-support optimization strategy for simultaneous multi-part processing is proposed. For optimization, the method selects the appropriate printing direction of one part, and then combines multiple parts to form a shared support structure to minimize energy consumption. Finally, under the constraint of minimizing the mass, an optimization strategy of the SLM multi-part shared support combination is established, and the purpose of reducing the energy consumption and material consumption of the SLM is achieved under the premise of ensuring the geometric accuracy of the parts. The method was applied to the manufacturing process of a group of parts with a beam structure. Compared with the printing method using independent support, the shared support structure method reduced energy consumption more than 5.5%, material consumption for the support structure more than 17.2%, and printing time to a certain extent. This method effectively improves SLM production efficiency and sustainability and provides strategic support for additive manufacturing designers and producers.