Stress and fatigue analysis of engine pistons using thermo-mechanical model

Zhenlei Chen,Jiancheng Li,Junxiong Liao,Fan Shi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9

This paper presents a thermo-mechanical finite element analysis model for the stress and fatigue analyses of engine pistons. The model consists of the piston, piston pin, piston ring, bushing, cylinder liner and connecting rod. The oil film and contact pressure are considered in the contact surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. A self-compiled code, which considers the factors of the piston skirt profile and ellipticity, is applied to calculate the initial clearance at the oil film surfaces between the piston and piston pin, the piston pin and bush, and the piston skirt and cylinder liner. The dynamic loads of the piston and connecting rod under the peak torque and peak power cases are calculated using powertrain commercial software, which are then used to carry out the stress and fatigue analyses. Compared with those published in literature, the present model is able to simulate the actual working conditions of the piston more accurately. The model can be used to evaluate and assess the piston skirt pressure, the stress and fatigue life of the concerned areas of the piston.

Model Identification and Human-robot Coupling Control of Lower Limb Exoskeleton with Biogeography-based Learning Particle Swarm Optimization

Qing Guo,Zhenlei Chen,Yao Yan,Wenying Xiong,Dan Jiang,Yan Shi 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.2

Lower limb exoskeleton is a typical wearable robot to assist human motion and improve physiological power. However, the control performance and stability are affected by some unknown model parameters and control algorithms. Therefore, it is necessary to investigate the model parametric identification and the control design of lower extremity exoskeleton. Firstly, the two degree-of-freedom (DoF) exoskeleton model is constructed by the Lagrange technique. Then the biogeography-based learning particle swarm optimization (BLPSO) is used to optimize the B-spline function parameters and the smooth stimulated trajectories is designed. Meanwhile, the BLPSO is also adopted to identify unknown model parameters of the exoskeleton based on the torques and the joint angles. To decline the negative effect of parametric identification error of exoskeleton, the passive backstepping controller is proposed to improve the tracking performance of human-robot motion. Furthermore, the active admittance controller is adopted to improve the motion comfort of tester. Finally, the comparative experimental results are verified on the platform, which show the BLPSO algorithm has better parametric identification accuracy than PSO and GA. Furthermore, the comparative results have verified that the proposed controller can improve the tracking behavior and reduce the human-robot interaction torque in wearable motion.

Thermal balance performance simulation and optimization of full-ground crane cabins

Yongkang Shi,Zhenlei Chen,Haitao He,Fan Shi,Penyong Liu,Yong Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2

To solve the excessive thermal load problem of the crane engine and engine compartment, a combined 1-D and 3-D thermal simulation method is developed to numerically simulate the heat flow field inside and outside the engine compartment, the engine thermal system and the cooling system. Simultaneously, to ensure the accuracy of the numerical calculation boundary and the feasibility of the combined thermal simulation method, the trailer heat balance test is conducted under the rated conditions and the maximum torque conditions. By reasonably sealing the heat dissipation assembly at the front of the nacelle, bottom guards under the engine are added and other improvement measures are taken. It is found that the engine outlet’s coolant temperature is decreased by 15.9 °C under rated conditions when the improved crane is in the 36 °C environment. While the outlet’s coolant temperature is decreased by 20 °C under maximum torque conditions.

Reconstruction of the Cervical Lateral Mass Using 3-Dimensional-Printed Prostheses

Qiang Jian,Zhenlei Liu,Wanru Duan,Jian Guan,Fengzeng Jian,Zan Chen 대한척추신경외과학회 2022 Neurospine Vol.19 No.1

Objective: This study aimed to investigate the outcome of using 3-dimensional (3D)-printed prostheses to reconstruct a cervical lateral mass to maintain cervical stability. Methods: We retrospectively analyzed data of 7 patients who underwent cervical lateral mass reconstruction using a 3D-printed prosthesis, comprising axial and subaxial lateral mass reconstruction in 2 and 5 patients, respectively. Bilateral mass was reconstructed in 1 patient and unilateral mass in the remaining 6 patients. Results: Using a 3D-printed lateral mass prosthesis, internal fixation was stable for all 7 patients postoperatively. No implant-related complications such as prosthesis loosening, displacement, and compression were observed at the last follow-up. Conclusion: Reconstruction of the lateral mass structure is beneficial in restoring load transfer in the cervical spine under physiological conditions. A 3D-printed prosthesis can be considered a good option for reconstruction of the lateral mass as fusion was achieved, with no subsequent complications observed.

circSPG21 protects against intervertebral disc disease by targeting miR-1197/ATP1B3

Huang Yizhen,Zhang Zhenlei,Wang Jianle,Shen Shuying,Yao Teng,Xu Yining,Chen Zizheng,Fang Bin,Ma Jianjun 생화학분자생물학회 2021 Experimental and molecular medicine Vol.53 No.-

The abnormal expression of circular RNAs (circRNAs) is associated with numerous human diseases. This study investigated the mechanism by which circRNA acts as competitive endogenous RNA in the regulation of degenerative intervertebral disc disease (IVDD). Decreased expression of circSPG21 was detected in degenerated nucleus pulposus cells (NPCs), the function of circSPG21 in NPCs was explored and verified, and the downstream target of circSPG21 was investigated. The interaction between circSPG21 and miR-1197 and its target gene ( ATP1B3 ) was studied by online database prediction and molecular biological verification. Finally, the circSPG21/miR-1197/ATP1B3 axis was verified in the mouse tail-looping model. The expression of circSPG21 in the nucleus pulposus in IVDD was directly related to an imbalance of anabolic and catabolic factors, which affected cell senescence. circSPG21 was found to play a role in human NPCs by acting as a sponge of miR-1197 and thereby affecting ATP1B3 . The regulation of circSPG21 provides a potentially effective therapeutic strategy for IVDD.

Location Distribution of Fistulas and Surgical Strategies for Spinal Extradural Meningeal Cysts: A Retrospective Analysis of 30 Cases at a Single Center

Qiang Jian,Gang Song,Zhenlei Liu,Wanru Duan,Jian Guan,Fengzeng Jian,Zan Chen 대한척추신경외과학회 2022 Neurospine Vol.19 No.1

Objective: This study aimed to illustrate the features of fistula location distribution, surgical strategies, and outcomes in spinal epidural meningeal cysts (SEMCs). Methods: The authors searched and reviewed the medical records for cases of SEMCs. Imaging features, operative reports, and media were reviewed to accurately describe the surgical techniques employed. We recorded the level and laterality of the fistula according to the operative report and the media. Consistency analysis was performed on the dominant laterality of the cyst on preoperative axial magnetic resonance imaging and laterality of the fistula in the operative media or report. When cyst and fistula lateralities were the same, they were considered consistent. Finally, the Japanese Orthopedic Association (JOA) score was used to obtain patient-reported results at each follow-up. Results: Thirty patients with SEMCs were identified. Fistula repair was performed in all patients. Two patients experienced cyst recurrence after surgery and were repaired during the second surgery. Based on imaging findings, SEMCs mostly occurred in the thoracolumbar junction. Most of the fistulas (87.88%) were at the T12 or L1 levels. In patients with multiple adjacent SEMCs, the fistula may be at one end of the cyst rather than in the middle level of the cyst. A fistula laterality of 72.72% was consistent with cyst laterality. The JOA improvement rate was 61.84% ± 26.63%. Conclusion: Most fistulas were always located at the T12–L1 level as well as the middle level of the cyst, which is always consistent with cyst laterality. In patients with multiple adjacent SEMCs, the fistula may be at one end of the cyst. Cleft closure is key to healing SEMCs.

Relationship Between Syrinx Resolution and Cervical Sagittal Realignment Following Decompression Surgery for Chiari I Malformation Related Syringomyelia Based on Configuration Phenotypes

Chunli Lu,Longbing Ma,Jian Guan,Zhenlei Liu,Kai Wang,Wanru Duan,Zan Chen,Hao Wu,Fengzeng Jian 대한척추신경외과학회 2022 Neurospine Vol.19 No.4

Objective: Combined with different configuration types of syringomyelia, to analyze the correlation between syrinx resolution and changes in cervical sagittal alignment following Foramen magnum and Magendie dredging (FMMD) for syringomyelia associated with Chiari I malformation (CM-I), and to further explore the respective relationship with clinical outcome. Methods: A consecutive series of 127 patients with CM-I and syringomyelia who underwent FMMD in our center met the inclusion criteria of this study. Their clinical records and radiologic data were retrospectively reviewed. The Japanese Orthopedic Association (JOA) scoring system and the Chicago Chiari Outcome Scale (CCOS) were used to evaluate the surgical efficacy. The phenotypes of syringomyelia and the clinical characteristics of the patients were analyzed according to grouping by cervical curvature at baseline. Results: The preoperative straight or kyphotic cervical alignment is more common in the moniliform syrinx. After surgery, the syrinx resolution and cervical sagittal realignment in the moniliform group are more obvious, and the corresponding prognosis is relatively better. Spearman correlation analysis showed that the ΔS/C ratio (the change ratio of syrinx/cord) was positively correlated with the CCOS (p = 0.001, r = 0.897) and ΔC2–7A (the change of lower cervical angle) (p = 0.002, r = 0.560). There was also a correlation between the ΔJOA score (the change rate of the JOA score) and ΔC2–7A (p = 0.012, r = 0.467). Conclusion: After decompression surgery, syrinx resolution may coexist with the changes in the subaxial lordosis angle, especially for syrinx in moniliform type, and the relationship between syrinx resolution and cervical sagittal realignment might be valuable for evaluating the surgical outcome.

Quantitative Reduction of Basilar Invagination With Atlantoaxial Dislocation by a Posterior Approach

Jian Guan,Fengzeng Jian,Qingyu Yao,Chenghua Yuan,Can Zhang,Longbing Ma,Zhenlei Liu,Wanru Duan,Xingwen Wang,Xuefeng Bo,Zan Chen 대한척추신경외과학회 2020 Neurospine Vol.17 No.3

Objective: This study evaluated the feasibility and efficacy of quantitative reduction and fixation to treat basilar invagination (BI) with atlantoaxial dislocation (AAD). Methods: Posterior occipitocervical angle (POCA), occiput–C2 angle (Oc–C2A), clivusaxial angle (CAA), and C2–7 angle (C2–7A) were considered for quantitative reduction. Twelve patients with BI complicated with AAD received posterior interarticular release and individualized cage implantation to restore vertical dislocation. The POCA was adjusted using cantilever technology to further reduce the horizontal dislocation and adjust lower cervical vertebral angle. All patients received a radiological follow-up for ≥12 months. Improvements in spinal cord function were evaluated using Japanese Orthopedic Association (JOA) score. Results: All the patients received successful quantitative reduction for BI-AAD, and bony fusion was achieved without spinal cord injury after surgery for 12 months. The JOA score was improved significantly to 15.2 ± 0.9 twelve months after surgery (p < 0.01). Radiological follow-up revealed that individualized cage and POCA play vital roles in quantitative correction: (1) distance of the dens above McRae’s line and atlantodens interval were restored to normal level, respectively; (2) changes in Oc–C2 angle (ΔOc–C2A), C2–7 angle (ΔC2–7A), clivus-axial angle (ΔCAA), and POCA (ΔPOCA) were all caused by changes in axis tilt. Based on the changes of radiological parameter we deduced the formula for quantitative reduction by linear regression analysis: -ΔPOCA = ΔOc–C2A = -ΔC2–7A = ΔCAA. Conclusion: Quantitative posterior reduction by individualized cage and adjusting ΔPOCA is feasible for treating BI with AAD.

Role of Preoperative Albumin Quotient in Surgical Planning for Posttraumatic Syringomyelia: A Comparative Cohort Study

Pingchuan Xia,Houyuan Lv,Chenghua Yuan,Wanru Duan,Jiachen Wang,Jian Guan,Yueqi Du,Can Zhang,Zhenlei Liu,Kai Wang,Zuowei Wang,Xingwen Wang,Hao Wu,Zan Chen,Fengzeng Jian 대한척추신경외과학회 2024 Neurospine Vol.21 No.1

Objective: Surgical procedures for patients with posttraumatic syringomyelia (PTS) remain controversial. Until now, there have been no effective quantitative evaluation methods to assist in selecting appropriate surgical plans before surgery. Methods: We consecutively enrolled PTS patients (arachnoid lysis group, n = 42; shunting group, n = 14) from 2003 to 2023. Additionally, 19 intrathecal anesthesia patients were included in the control group. All patients with PTS underwent physical and neurological examinations and spinal magnetic resonance imaging preoperatively, 3–12 months postoperatively and during the last follow-up. Preoperative lumbar puncture was performed and blood-spinal cord barrier disruption was detected by quotient of albumin (Qalb, cerebrospinal fluid/serum). Results: The ages (p = 0.324) and sex (p = 0.065) of the PTS and control groups did not differ significantly. There were also no significant differences in age (p = 0.216), routine blood data and prognosis (p = 0.399) between the arachnoid lysis and shunting groups. But the QAlb level of PTS patients was significantly higher than that of the control group (p < 0.001), and the shunting group had a significantly higher QAlb (p < 0.001) than the arachnoid lysis group. A high preoperative QAlb (odds ratio, 1.091; 95% confidence interval, 1.004–1.187; p = 0.041) was identified as the predictive factor for the shunting procedure, with the receiver operating characteristic curve showing 100% specificity and 80.95% sensitivity for patients with a QAlb > 12.67. Conclusion: Preoperative QAlb is a significant predictive factor for the types of surgery. For PTS patients with a QAlb > 12.67, shunting represents the final recourse, necessitating the exploration and development of novel treatments for these patients.