Manual Material Research Articles

The Role of Technical Support and Effective Communication to Successful Intervention Program on Palm Oil Mills

The palm oil mills demand the workers perform manual material still managing activities, which results in pain complaints leading to possible disability. These pain complaints can be resolved by implementing an intervention program involving all parties. Most previous studies only investigated the program implementation, and few addressed workers' behavioral responses. Organizational culture, which may affect the correlation between organizational climate and the effectiveness of intervention programs, has never been properly studied. This study aims to determine how the interaction between technical support and effective management-worker communication on the effectiveness of the intervention program by considering the influence of organizational culture. Understanding worker acceptance of intervention programs can determine how to implement them effectively. All these research variables were analyzed simultaneously using Partial Least Squares Structural Equation Modeling (PLS-SEM) software, in which data were obtained from questionnaires given to 280 people working in 20 government-owned and private-owned palm oil mills in North Sumatra Province. The results show that technical support and effective communication affect the effective intervention program, but effective communication has a bigger effect. Organizational climate mediates the effects of technical support and effective communication on effective intervention programs. Organizational culture negatively moderates the correlation between organizational climate and effective intervention programs. The dimensions of organizational culture in palm oil mills are high power distance, high uncertainty avoidance, collectivism, masculinity, long-term orientation, and restraint.

Heart rate variability based physical exertion monitoring for manual material handling tasks

Physical exertion monitoring has been strongly emphasized to avert the ill-effects of physically demanding nature of many industries such as construction. Recently, several sensors-based approaches have been suggested as an alternative to traditional subjective feedback-based methods. Although the proposed sensor-based approaches have laid the foundation for automated physical exertion monitoring, they require multiple on-body and/or off-body sensors to collect psychological, physiological, acceleration/posture or weather-related data. As such, multiple on-body sensors may instigate irritation and discomfort whereas other off-body sensors require additional resources for handling and managing them. To address these limitations, taking a minimalistic approach, this study explored the use of heart rate variability (HRV) metrics which could be computed from a single electrocardiogram or optical sensor (often found in fitness wrist bands and smart watches). For this purpose, manual material handling experiments were conducted while state-of-the-art HRV features were used to perform physical exertion monitoring with ensemble classifiers and artificial neural network (ANN) based regression analysis. The results indicate that ensemble classifiers achieved accuracies from 64.2% to 81.2%, depending on the number of levels in which physical exertion data was divided, whereas ANN regression achieved the least root mean square error of 1.651. Given the wide availability of HRV sensors in fitness bands and wrist watches, this study highlights the usability and limitations of HRV based physical exertion monitoring which could help make informed decisions related to its adoption in physically demanding industries such as construction.

Application of 5D Building Information Modeling for Construction Management

Smart technologies are currently trending in the Indian construction industry for management. One such technology is Building Information Modeling (BIM). This research talks about fourth and fifth dimensions of BIM and its applications. In the present study, two methods of material take-offs are compared, Manual Material Take-Offs and Digital Material Take-Offs. Here, the case study of an industrial project is considered, located in Surat City. Focus is given on three major construction materials: cement, sand, and aggregates. Manual Material Take-Off is estimated using physical plans and Excel sheets, while for Digital Material Take-Off number of software are used like Revit, Primavera, and Navisworks Manage. Based on the result, it can be judged that Digital Material Take-Off is more accurate compared to Manual Material Take-Off. In addition to this, BIM has added advantages of time and cost management, information management, faster decision making, etc.

A Case Study of Ergonomics Prevention Program in a Machine Manufacture Industry

Musculoskeletal Disorders (MSDs) is the most potential risks in human production and economic systems. In this research, ergonomics guidelines and enacted relevant regulations announced by other countries to effectively facilitate ergonomics prevention programs were discussed. A machine manufacture industry as a case study has been ergonomically evaluated by Musculoskeletal Disorders Checklist (MSDs) and Nordic Musculoskeletal Questionnaire (NMQ), which was used to recognize the dominating risk factors. According to the result of observation and preliminary assessment, low back pain related to the high frequency of manual material handling tasks was the critical issue in this case study. The conclusion revealed that the proposed improvement such as engineering redesign, training, health management, and administration, would be implemented into the main axle assembly area, customer service department, and Z-axis assembly area. The further improvement interventions would help organization to carry out the ergonomics prevention program.

The impact of using wearable devices on the operator during manual material handling tasks

There has been a recent advent in the use of wearable devices in the workplace as these technologies offer an opportunity to track product movement through the warehousing and material handling process. This study examines the use of a wand scanner and two wearable devices (ring scanner and smart glasses) on forty healthy participants to study comfort, discomfort and performance while executing shipment putting tasks. The impact of wearables was investigated using the Comfort Rating Scales and Body Discomfort Scale. Participants identified the ring and wand scanner as the most comfortable device. Participants became more uncomfortable using the smart glasses over time during the completion of the task. While using the glasses, the participants experienced discomfort in the eye, neck, and shoulder. This research shows that there is a need for additional improvement with smart glasses before incorporating this technology into the workplace. Companies contemplating incorporating smart glasses to improve productivity can use the results of this study to identify important features needed to optimize this device. Likewise, companies interested in shifting away from handheld scanning technologies to wearable solutions can consider ring scanners and similarly donned devices as performance enhancing solutions. Relevance to industryThis study investigates productivity, comfort, and discomfort of standard material handling tasks through the comparison of multiple scanning devices including a commonly used wand scanner and two wearable solutions (smart glasses and a ring scanner). Ring scanner of most productive with smart glasses being both the least productive and comfortable.

A Systematic Review of Industrial Exoskeletons for Injury Prevention: Efficacy Evaluation Metrics, Target Tasks, and Supported Body Postures.

Industrial workplaces expose workers to a high risk of injuries such as Work-related Musculoskeletal Disorders (WMSDs). Exoskeletons are wearable robotic technologies that can be used to reduce the loads exerted on the body’s joints and reduce the occurrence of WMSDs. However, current studies show that the deployment of industrial exoskeletons is still limited, and widespread adoption depends on different factors, including efficacy evaluation metrics, target tasks, and supported body postures. Given that exoskeletons are not yet adopted to their full potential, we propose a review based on these three evaluation dimensions that guides researchers and practitioners in properly evaluating and selecting exoskeletons and using them effectively in workplaces. Specifically, evaluating an exoskeleton needs to incorporate: (1) efficacy evaluation metrics based on both subjective (e.g., user perception) and objective (e.g., physiological measurements from sensors) measures, (2) target tasks (e.g., manual material handling and the use of tools), and (3) the body postures adopted (e.g., squatting and stooping). This framework is meant to guide the implementation and assessment of exoskeletons and provide recommendations addressing potential challenges in the adoption of industrial exoskeletons. The ultimate goal is to use the framework to enhance the acceptance and adoption of exoskeletons and to minimize future WMSDs in industrial workplaces.

Different Phases in Manual Materials Handling Have Different Performance Criteria: Evidence From Multi-Objective Optimization.

A manual material handling task involves the phases of reaching, lifting, unloading, and standing up (RLUS). Understanding the mechanisms of manual material handling is important for occupational health and the development of assist devices. Predictive models are becoming popular in exploring which performance criterion is appropriate in the lifting phase. However, limited attempts have been performed on the other phases. The associated performance criterion for predicting other phases is unknown. In this study, an optimization model for predicting RLUS has been developed with the multi-objective optimization method. Two performance criteria (minimum dynamic effort and maximum balance) were studied to explore their importance in each phase. The result shows that maximum balance leads to joint angle errors 27.6% and 40.9% smaller than minimum dynamic effort in reaching and unloading phases, but 40.4% and 65.9% larger in lifting and standing up phases. When the two performance criteria are combined, the maximum balance could help improve the predicting accuracy in the reaching, lifting, and unloading phases. These findings suggest that people prefer different performance criteria in different phases. This study helps understand the differences in motion strategies in manual materials handling (MMH), which would be used to develop a more accurate predictive model.

Risk events recognition using smartphone and machine learning in construction workers' material handling tasks

PurposeThe outbreak of the pandemic makes it more difficult to manage the safety or health of construction workers in infrastructure construction. Risk events in construction workers' material handling tasks are highly relevant to workers' work-related musculoskeletal disorders. However, there are still many problems to be resolved in recognizing risk events accurately. The purpose of this research is to propose an automatic and non-invasive recognition method for construction workers in material handling tasks during the pandemic based on smartphone and machine learning.Design/methodology/approachThis research proposes a method to recognize and classify four different risk events by collecting specific acceleration and angular velocity patterns through built-in sensors of smartphones. The events were simulated with anterior handling and shoulder handling methods in the laboratory. After data segmentation and feature extraction, five different machine learning methods are used to recognize risk events and the classification performances are compared.FindingsThe classification result of the shoulder handling method was slightly better than the anterior handling method. By comparing the accuracy of five different classifiers, cross-validation results showed that the classification accuracy of the random forest algorithm was the highest (76.71% in anterior handling method and 80.13% in shoulder handling method) when the window size was 0.64 s.Originality/valueLess attention has been paid to the risk events in workers' material handling tasks in previous studies, and most events are recorded by manual observation methods. This study provided a simple and objective way to judge the risk events in manual material handling tasks of construction workers based on smartphones, which can be used as a non-invasive way for managers to improve health and labor productivity during the pandemic.

Trunk muscle activity during holding two types of dynamic loads in subjects with nonspecific low back pain

BackgroundChronic low back pain due to manual lifting continues to be one of the significant common public health challenges in modern societies despite increased automation. While there are extensive studies on the biomechanics of lifting as associated with LBP, the role of unstable and time-varying dynamic loads, quite common in industrial lifting and daily life, remains elusive. ObjectivesThe present study aimed to investigate the response of trunk muscles in subjects with chronic non-specific low back pain (CNLBP) while holding unstable dynamic loads. MethodsTwelve male patients with CNLBP and twelve healthy controls participated in this cross-sectional study. The subjects held static and dynamic loads in neutral positions. Normalized EMG data of the trunk muscles were captured and analyzed by repeated-measures ANOVA test. ResultsThe low back pain group demonstrated significantly higher activation levels of the internal and external abdominal oblique muscles while holding dynamic loads (p < 0.05). ConclusionOur results suggest that the neuromusculoskeletal system in low back patients holding dynamic loads may invoke a motor control strategy that significantly increases muscle co-activation leading to higher joint stiffness at the expense of higher compressive loads on the lumbar spine. Importantly, the type of load plays a critical role in terms of external perturbations that may lead to spinal injury in CNLBP patients and must, therefore, be considered in the risk prevention and assessment of lifting and other manual material handling tasks.

The Importance of Lifting Height and Load Mass for Muscular Workload during Supermarket Stocking: Cross-Sectional Field Study

High physical work demands increase the risk of musculoskeletal disorders and sickness absence. Supermarket work involves a high amount of manual material handling. Identifying specific ergonomic risk factors is an important part of occupational health and safety efforts in the supermarket sector. In this cross-sectional field study among 64 supermarket workers, we used electromyography during the workday to determine the influence of lifting height and load mass on muscular workload of the low-back and neck/shoulder muscles during un-restricted manual material handling (grocery stocking). We found a significant effect of load mass, i.e., higher loads associated with higher muscular workload in the low-back and neck/shoulder muscles. We demonstrated a significant interaction between start and end position, i.e., lifts performed from ‘Low’ start positions to ‘High’ end positions demonstrated the highest low-back muscular workload, whereas ‘High’ positions were associated with increased neck/shoulder workload. In conclusion, lifting higher loads and lifting goods from low to high positions (low-back) and at high positions (neck/shoulder) are associated with higher muscular workload. These results can be used to guide highly warranted preventive initiatives to reduce the physical workload during supermarket work.

Bye Bye Binary: Reimagining Gender in An Unkindness of Ghosts

Bye Bye Binary: Reimagining Gender in An Unkindness of Ghosts Kamri Jordan (bio) There is no rulebook for navigating oppressive systems, but oppression cannot eradicate discovery and creation. Marginalized groups rely on a multitude of practices to assert their subjectivity against institutions that say otherwise. One such method that has lasted for centuries is the act of storytelling, which for African Americans over the years has taken many forms ranging from work songs, spirituals, and slave narratives to dramas, poetry, and novels. The last of these forms is exemplified by the contemporary counter-story created in Rivers Solomon’s An Unkindness of Ghosts (2017). Aboard a spaceship in a post-climate catastrophe future, Solomon presents a society where institutional oppression and slavery remain upheld. With an Afrofuturist structure, Solomon pushes for a new vision of Black people’s subjectivity, and agency develops within and against systems that seek to deny them such. Aboard the HSS Matilda, residents are separated into the Upper and Lower Decks. Divided by Solomon’s imagined caste system, upperdeckers live a life of comfort, while the lowerdeckers ensure the ship’s day-to-day running. However, all are put in peril as a problem with the Matilda’s energy source causes a series of blackouts. Amidst the quest to solve the mystery of these blackouts, characters such as the protagonist Aster seek to find their identities. Following the notes left behind by her deceased mother, who was a former technician on the ship, Aster connects the mystery of the ship to that of her own identity. Thus, as the Matilda faces the instability and challenges brought on by the blackouts, Aster also takes the time to evaluate her own positionality. Through Aster’s exploration, An Unkindness of Ghosts becomes a counter-story of gender and sexuality. Under the oppressive caste system and the turmoil caused by blackouts, the lower deck communities become spaces for sexual and gendered violence. However, under this oppression, characters such as Aster fight to understand and claim their gender and sexual identities rather than those forced on them by the oppressive systems of Matilda. I argue that the novel offers a space to rethink Blackness, gender subjectivity, and sexual agency. While the characters operate within their own futuristic chattel slavery society, they also engage with conversations on gender and sexuality that dominate our present-day discourse. Thus, An Unkindness of Ghosts does not create an idyllic future of freedom and gender and sexual liberation. Instead, Solomon shows that Afrofuturism is a space in which it is possible to reconsider and imagine Black people’s relationship with gender and sexuality in the past and present so that the future creates new avenues of subjectivity and agency. [End Page 23] An Unkindness of Ghosts opens three hundred years after the destruction of the Great Lifehouse, the novel’s presentation of Earth, with Aster aboard the Matilda and preparing to amputate the foot of a lowerdeck child, Flick. Flick and Aster are united through their shared social status; both are lowerdeckers and belong to the Tarlander classification. The Tarlanders are the residents of P, Q, R, S, and T decks, and as Aster describes them, “as close to a nation as anything on Matilda” (Solomon 11). The Tarlanders provide the manual labor to sustain life onboard the Matilda. Each day thousands of lowerdeckers go to work on the Field Decks. Rotating around the ship’s artificial sun, known as Baby Sun or Baby, the Field Decks are described by Aster as being “of varying size, each of them a different field, forest, or orchard” (73). Also, an estimated eight thousand workers reported working the fields during Aster’s shift, with two of the Tarland decks represented (70). Though the Tarlanders exist physically and socially at the bottom of Matilda’s structure, they are crucial to its operation. They provide manual labor and material resources that keeps the Matilda afloat. Seventy years after the Matilda began its voyage, there had been a decline in the Tarlander population (19). Dependent upon the labor of the Tarlanders, this decline was of grave concern to the authorities of the Matilda, referred to as the Guards and the Sovereign...

Quantifying the Effect of Mental Stress on Physical Stress for Construction Tasks

Because of labor-intensive and physically demanding tasks, construction workers are known to be at a higher risk of developing physical fatigue. Recent studies have shown that construction workers are also often exposed to considerable mental stresses. While a number of studies have proposed methods and tools to measure and monitor physical and mental stress disjointedly, there is a need to explore their interaction. The literature indicates that no previous study has endeavored to evaluate the effect of mental stress on physical stress for construction tasks. This investigation is necessary to better comprehend work demands of construction tasks. Accordingly, entailing a randomized crossover design and simulated manual material handling experiment, this study evaluated the effect of cognitive task-led mental stress on physical stress using both subjective (ratings of perceived exertion) and objective measures (heart rate, skin temperature, and skin conductance). The results revealed that cognitive task-led mental stress led to a significant increase in subjective ratings of perceived exertion accompanied by an increase in skin temperature and skin conductance, while heart rate remained unaffected. The findings of this study add to the body of knowledge by highlighting that traditional benchmarking of task demands using only physiological measures may not be comprehensive. Rather, it might be suggested that additional psychological measurements are also essential because they might affect physical stress development. Furthermore, the current study has increased our understanding related to the interaction of physical and mental stress by revealing interindividual differences among the participants. Accordingly, by examining each worker separately, practitioners and safety managers can develop better mitigation strategies and individualized training programs, especially for more vulnerable workers, which can enhance overall health and safety on construction job sites.

EFFECT OF LOAD ON GAIT

Introduction: Material Handling is one of the major activities performed by the workforce in the present scenario in industries. Our study aims to do the experiment with 22 different subjects and to collect the data using MiniSun IDEEA3 Gait Analysis instrument and to analyse the parameters Speed, EE and Stride length and find preventable measures to reduce fall risk. Material and Methods: Gait analysis experiment has been done with the subject with backpack and double pack with load of 5 kg and 10 kg. In the Industrial scenario, from construction site to cement industry, workers are carrying the load from one place to another. For instance, the typical scenario includes the transferring the load in backpack. All experiments were done in the institutegymnastic. Our study methodology deals with the conditions of experimentation, how sensors, recorder and sub recorder attached to subject body and how its working. This includes subject experiment conditions such as subject is walking on even surface and stairs with 5 kg backpack, 10 kg backpack and 5 kg double pack. When subject walks, data gets collected in recorder from sub recorder through wirelessly. Results: When subject walks with 10 kg backpack load gait parameters shows the worst condition i.e. prone to fall. However, if 10 kg backpack load distributed to 5 kg each side front and rear i.e. called double pack result shows a reliable change i.e. a safe limit to prevent the fall risk. So rather than preferring a backpack, double pack would be recommendable to prevent fall risk. The reason behind speed reduction is shorter steps with carrying load as compare to no load, which fails to maintain minimum unimpaired walking speed 55m/min. But greater than 75 m/min suggested to exceptional life expectancy. But not prove to be best in reduced fall risk while carrying. When load increases, speed get decreases, energy expenditure increases, stride length decreases. These all-gait parameters indicate a significant change that is the major cause of fall during manual material handling in industries. Conclusion: So those with high BMI if carry material in manual material handling industries, the Speed and EE will be major and considerable factor to fall. Thus Speed and energy expenditure needs to be investigated with Influence of walking speed, external load, energy expenditure and power on gait characteristics, to find the relationship between the risk of injury to kinematic changes due to external load on speed, energy expenditure and power.

Application from South Korea on the decomposition of the strategic procedure of IPO proceeds

The study’s key aim is to decide what South Korean initial public offering (IPO) issuers indicate as their intended usage of IPO proceeds, as well as the use with the highest amount of allocation, and whether the allocation of IPO proceeds to each intended use varies across industries. In order to fulfil the study’s target, a manual material review of prospectuses from 235 IPO issuers was conducted between 2005 and 2015. Descriptive statistics, one-way analysis of variance, Independent Sample [Formula: see text]-test, and Wilcoxon Rank Sum Test were used to evaluate the results. The findings reveal that issuers plan to use IPO proceeds for a range of purposes. Capital investment, on the other hand, earned the largest volume and proportion of IPO proceeds, followed by debt restructuring and company growth. The trend of allocation of IPO proceeds for a particular purpose is affected by the industry classifications of issuers, according to further research using the Independent Sample [Formula: see text]-test and Wilcoxon Rank Sum Test, since there is a statistically relevant discrepancy between the mean values of allocation of IPO proceeds across industries. The technology sector, for example, has a statistically higher mean research and development (R&amp;D) score than other sectors. As a result, future research into how the expected usage of IPO proceeds impacts subsequent IPO results will be important.

Classifying hazardous movements and loads during manual materials handling using accelerometers and instrumented insoles

Improper manual material handling (MMH) techniques are shown to lead to low back pain, the most common work-related musculoskeletal disorder. Due to the complex nature and variability of MMH and obtrusiveness and subjectiveness of existing hazard analysis methods, providing systematic, continuous, and automated risk assessment is challenging. We present a machine learning algorithm to detect and classify MMH tasks using minimally-intrusive instrumented insoles and chest-mounted accelerometers. Six participants performed standing, walking, lifting/lowering, carrying, side-to-side load transferring (i.e., 5.7 kg and 12.5 kg), and pushing/pulling. Lifting and carrying loads as well as hazardous behaviors (i.e., stooping, overextending and jerky lifting) were detected with 85.3%/81.5% average accuracies with/without chest accelerometer. The proposed system allows for continuous exposure assessment during MMH and provides objective data for use with analytical risk assessment models that can be used to increase workplace safety through exposure estimation.

Effect of using real motion versus predicted motion as input for digital human modeling of back and shoulder loads during manual material handling

Digital human modeling (DHM) technology is considered the state of the art in designing and evaluating workstations. Previous studies examined the differences between DHM's posture and motion prediction relative to human experimental data. Yet, the effect the two different inputs on biomechanical loads was not assessed. Therefore, this study evaluates the differences in L4/L5 compression force and shoulder torques during a work process calculated using DHM with motion prediction (Jack by Siemens) and DHM with experimental data. The work process is a sequential removing, carrying, and depositing task performed by nine females and nine males and recorded using a motion capture system. The analysis shows that using experimental data results in larger back compression force during the removing task (average 15.4%), similar force during the depositing task (average 0.68%), and less force during the carrying task (19.875%). Using experimental data resulted in larger shoulder torque during all tasks (average 24.97%).

ANALISIS POSTUR KERJA MANUAL MATERIAL HANDLING (MMH) MENGGUNAKAN RAPID UPPER LIMB ASSESSMENT (RULA) DI PT.XYZ

The use of human labor in the industrial world in Indonesia is still very dominant, especially in Manual Material Handling (MMH) activities. The activity of bending and twisting in the workplace while doing MMH should be reduced or even if possible this activity should be eliminated because this attitude is prone to causing disorders of the musculoskeletal system. Considering that MMH activities have a vital role in the work carried out in the production process section, therefore the researcher will conduct an analysis of the Manual Material Handling (MMH) work posture using the Rapid Upper Limb Assessment (RULA). RULA is a work posture research method to investigate disorders of the upper limbs. The results of the work posture analysis based on the results of the assessment using the RULA method stated that all manual material handling activities assessed above required corrective action or efforts. In the shuttle area, the final score for the action category obtained is 7 with a high risk level and the action that must be taken is action now. In the Pirn Winder area, the final score for the action category obtained is 6 with a moderate risk level and the action that must be taken is action in the near future. In the vacuum heat setter area, the final score for the action category obtained is 7 with a high level of risk and the action that must be taken is action now.

Lifting capacity prediction model using physical performance measures among construction workers

Manual materials handling is performed in many workplaces and is a significant risk factor for musculoskeletal injuries. The identification of lifting capacity is important to reduce the occurrence of musculoskeletal injuries. Lifting capacity is difficult to evaluate at the workplace. Therefore, there is a need to develop an alternate method that is easy and could be performed at the workplace. The study aimed to develop a lifting capacity prediction model for construction workers based on muscle strength and endurance. In this study, 65 construction workers were recruited; their socio-demographic and physical characteristics like core strength and endurance, grip strength, and lower limb flexibility were assessed. The lifting capacity was assessed using progressive isoinertial lifting evaluation. Stepwise multiple linear regression was carried out to develop the prediction model. The study suggested that age, BMI, grip strength, flexibility, prone plank, and trunk lateral flexor endurance tests have significantly influenced lifting capacity. Hence prediction model is developed using these variables. The regression model developed would help in easy estimation of lifting capacity among construction workers, which could be even administered with minimal skills by site supervisors or managers. It might help in the decision-making during pre-placement or return to work evaluations, thereby minimizing the incidence of low back disorders.

Manufacturing Operator Ergonomics: A Conceptual Digital Twin Approach to Detect Biomechanical Fatigue

The primary sources of injuries in the workplace are improper manual material handling (MMH) motions, forklift collisions, slip, and fall. This research presents a Digital Twin (DT) framework to analyze fatigue in humans while performing lifting MMH activity in a laboratory environment for the purpose of reducing these types of injuries. The proposed methodology analyzes the worker’s body joints to detect biomechanical fatigue as a factor of change in back, elbow, and knee joint angles. Using the dynamic time warping (DTW) algorithm, the change in joint angles with time was analyzed. The variation in DTW parameters was evaluated using exponentially weighted moving average (EWMA) control charts for further analysis. A preliminary study considering two healthy male subjects performing seven experiments, each under an optical motion capture system was performed to test the model’s efficiency. Our contributions are twofold. First, we propose a model to detect biomechanical fatigue in the subjects performing MMH lifting activity as a change in joint angles. Secondly, the research also shows evidence that different individuals show signs of body fatigue via different body joints and showcases the need for a true personalized DT for an operator for fatigue assessment in an MMH environment.

Concept of mathematical modeling of lumbar and thoracic spine based on elastic beam theory

Modeling of the human spine is important for establishing quantitative assessment methods of low back pain (LBP) caused by manual material handling (MMH). This study developed mathematical models of the lumbar and thoracic spine based on the elastic beam theory. Two types of models, uniform and non-uniform, were derived. First, to simplify the Bernoulli-Euler beam theory, three assumptions were introduced for the uniform beam model: (i) the vertebrae and intervertebral disc were considered as a composite material, (ii) constant cross-sectional area, and (iii) conversion of muscular strength to bending moment. However, on fitting to the actual spine position data from the literature, the uniform beam model was found to be unable to reproduce the spine shape, particularly in the lumbar region. Therefore, the non-uniform beam model was derived by removing assumption (ii), which does not agree with the actual human spine profile. Consequently, the spine was modeled as a trapezoid from around S1 to C7 in the sagittal plane, by adjusting the proportionality factor of trapezoid via tapering or widening, and the non-uniform beam model was found to better reproduce the spine shape, including the lumbar region. The model has practicability, such as estimation of spine shape; however, the proportionality factor that was used to reproduce the spine shape did not agree with the actual human spine profile; further theoretical development has been left as future work.