Sharif Digital Repository

Nowadays, Eye injuries caused by blunt impacts are considered among the major causes of blindness and vision problems; therefore, studying the existence of possible damages can be quite useful and effective. One of the quickest and most suitable methods in identifying damage parameters is finite-element modeling of the human eye. In this regard, in the current study, first a geometrical design was created by incorporating CT-Scan images of the eye into Mimics and later Solid works software. Afterwards, the most suitable mechanical properties for the constituents of the eye were extracted from the literature. The mechanical properties of vitreous and Sclera were obtained by experimental... 

Most elderly and physically disabled people suffer from lack of functionality and dexterity in their elbow or wrist. These disabilities are due to the damages mostly caused by sport surgery, spinal surgery, or stroke. Therefore, design of an assistive exoskeleton robot for upper limb movements seems necessary. The purpose of this study is to design, fabricate and deliver a control algorithm for an assistive wearable robot. The robot has five degrees of freedom in order to help the flexion/extension and abduction/adduction shoulder. Dynamic and kinematic model of elbow, forearm, and wrist is developed to determine the amounts of torques which are required in the joint actuators mounted on the... 

Subdural hemorrhage (SDH) is one of the most common traumatic brain injuries. The mortality rate of SDH is over 30 percent. In addition, patients require to visit hospital for treatment and further healthcare. According to the costs of treatment and frequency of injuries, prevention of SDH is essential. 3D-Finite element modeling of human head is an appropriate tool for evaluation of injury risk and setting up a prevention tolerance criteria. The aim of this study is to create a 3D finite element model of human head with special consideration of vessels. Vessels are modeled by truss elements at current finite element models of human head; however, geometry of vessels is regarded as simple... 

Range of motion (ROM) of the thoracic spine has implications in patient discrimination for diagnostic purposes and in biomechanical models for predictions of spinal loads. Few previous studies have reported quite different thoracic ROMs. Total (T1-T12), lower (T5-T12) and upper (T1-T5) thoracic, lumbar (T12-S1), pelvis, and entire trunk (T1) ROMs were measured using an inertial tracking device as asymptomatic subjects flexed forward from their neutral upright position to full forward flexion. Correlations between body height and the ROMs were conducted. Effect of measurement errors of the trunk flexion (T1) on the model-predicted spinal loads was investigated. Mean of peak voluntary total... 

Etiological studies proves the fact that Low Back Pain (LBP) is one of the most expensive and prevalent desease all over the world. This fact illustrates the reqiurment of the special effort in ordet to reducing the pain due to this problem. Finite element modeling of human spine is one the suitable methods to simulate the behavior of human spine in different loading conditions. These conditions could be different daily occupational tasks. There is two general viewpoint toward finite element modeling of human spine. The fisrt method focuses on the detailed geometry and mechanical properties of spine, while the other complexities such as detailed muscle forces are overlooked. The latter... 

The human brain is the most sensitive and important human organ and surgery must be done with high precision and without risk. During surgery, brain tissue deform continuously due to gravity, out of the cerebrospinal fluid and the changing pressure of the cerebrospinal fluid and the surgical maneuvers. Because the surgeon has no direct view on brain internal, the ways to solve this problem is to pay attention. This method makes it possible to the surgeon see in the brain and the brain tissue deformation. This thesis method is based on biomechanical modeling. After forming finite element model from the pre-operative MRI, brain surface and volume datasets during surgery as a load, apply to the... 

Posterior lumbar surgery is often associated with extensive injuries to back muscles. In this thesis, the effect of such iatrogenic injuries in some patients was examined. For this purpose, the CSA of back muscles in 6 patients were measured using MR scan. To examine any natural change in CSAs of healthy people or instrument errors, same measurement were carried out on 10 healthy volunteers. In addition, a detailed anatomical model of an intact human spine was developed. With the aim of experimental studies and intact model, the post-operative model of patients was also developed. These two models were used to quantizing the change in activity of back muscles during some symmetric, normal... 

Foot related problems or diseases such as plan foot pain, diabetic foot, arthritic foot, pathological flatfoot, ankle sprain, bone fracture or other sports related injuries have been costing a significant amount of medical expenditure. Abnormal loading patterns and high pressure on the foot as well as improper or ill-fitting footwear are thought to be one major mechanical cause of foot problems. Most ankle sprains respond favorably to nonsurgical treatment, such as those offered by physical therapists, doctors of chiropractic, and rehabilitation specialists. A comprehensive history and examination aid in diagnosing the severity and type of ankle sprain. Based on the diagnosis and an... 

Epidemiological studies have identified manual material handling and lifting as risk factors in occupational low back pain (LBP). There are many lifting analysis tools to estimate the risk of injury during a specific lifting task. One for using these tools, needs to know the limitations of each tool and be noticed where a tool cannot be used. The purpose of this study is to compare different biomechanical models of lumbar spine and find out their characteristics.Five models are chosen for this study which are: the University of Michigan’s Static Strength Prediction Program ( ) software, the revised Hand-Calculation Back Compressive Force (HCBCF) equation, the simple polynomial equation of... 

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess risk of injury to the spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses two biomechanical models of the spine to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies).Severallifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the models. In lifting activities involving moderate to large forward trunk flexion, the estimated RWL generates L5-S1 spine loads exceeding the recommended limits. The NIOSH vertical multiplier is the likely... 

In Former research we determinate elastic response of Brazilian Test of transversely Isotropic material . In Bio-mechanic science surveying mechanical properties and modeling biological organ such as bone , tooth and bio-material such as titanium, zirconium with application in joint replacement is very important . One of method to determine properties of bio-material which mostly has transversely Isotropic behavior is Brazilian Test. Also most rocks has transversely Isotropic behavior, so choosing efficient test is so important. In current issue , load apply in limited area and it is also considered friction in area of jaw loading area .By use of displacement potential function ... 

Low back pain is one of the musculoskeletal diseases which is an important issue for general health of society in both quality of life and costs. Most of the clinical instructions employ exercise as a clinical treatment in order to cure chronic low back pain. General and core stability exercises are of common prevalence, however, there are disputes about the effectiveness of these exercises in the literature. The aim of this study is to answer the question whether stabilizer exercise can significantly alter the stability of vertebral column in comparison with general exercises. Hence, experiments have been designed and conducted. The participants have been divided to two group. Within six... 

Regaining biomechanical function, comfort and quality of every-day life is a prime consideration when designing prosthetic devices for amputees. The magnetorheological (MR) prosthetic knee, which is the subject of this study, is an example of such a device. The study presents a comprehensive and a combined MR device design and MR fluid design approach, aiming to advance the MR prosthetic knee. First, this study focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. The new configuration is a rotary damper using MR fluid with a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main... 

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess the risk of injury to the spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses the AnyBody modeling software to verify whether the RWL generates L5-S1 within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in the literature). Twenty-four symmetric and asymmetric lifting activities were simulated to evaluate the RWL by the NLE and the L5-S1 loads by AnyBody. In two activities, involving large trunk flexion and 30 and 60 degrees of load asymmetry, the estimated RWL generated L5-S1 spine loads exceeding the recommended limits. The NIOSH... 

Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific... 

Obesity is a worldwide growing health challenge affecting ~30% of the world's population. Increased rate of disc degeneration and herniation, low back pain and surgery has been reported in obese individuals. Although obesity-related low back diseases have multifactorial etiology, presumably greater mechanical loads on the spine of heavier individuals during their daily activities may be considered as a risk factor. Likely larger trunk muscle sizes, disc sizes and thus passive stiffness in heavier individuals may however partly or fully offset the effect of their additional body weight on the spinal loads. In absence of in vivo approaches, the present study aims to construct subject-specific... 

Quantitative motion quality evaluation has been always of much significance for CVA patients, especially the HCP ones. The purpose of the present study is to introduce and analyze the efficiency of a novel index, namely “Consumed Energy Index”, for evaluating the quality of the motions performed by HCP patients. For this purpose, Firstly, a Musculo-Skeletal model of the human arm was provided on Matlab and OpenSim softwares, with four DoFs: three DoFs at shoulder and one DoF at elbow joint as well as eight muscles. The muscles are in pairs of flexor-extensor at each DoF. The model is capable of receiving Cartesian trajectories for joints and solving inverse kinematics and dynamics to obtain... 

A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible exercise bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response and forced one under excitation of the grip of the flexible bar is written parametrically. Some experiments are performed on a specific flexible bar to obtain numerical values for the parameters in the model to have it quantitatively known. In the next step, simulation of the model results in the response of the flexible bar under a considered excitation. The response is imported into a multi-segment musculoskeletal software, AnyBody,... 

Neck fracture caused by impacts on the head and neck during road accidents annually imposes a great cost to the people hospitals and the economy of country. Most of these accidents, regardless of cartilaginous injury causes sudden pressure to the spinal cord so it seems necessary to understand the biomechanical response of the neck and the mechanism of injury to reduce costs. Many computational models related to the neck injury have been developed recently. The aim of this project is to investigate the effect of frontal and rear impacts to the head and neck during road accidents. There are many researches have used elastic property for tissues but a little portion of research in this field... 

Parkinson's disease is the most common progressive neurological disorder after Alzheimer, which is associated with motor disabilities. One of the most effective ways to improve patient’s condition with this disease, is rehabilitation.Assessment of the patient during rehabilitation is very important in order to give a better understanding of patient's status to the specialist, but qualitative assessment methods in traditional rehabilitation are ineffective in fast and accurate evaluation of the patient's condition; and because of their need for patient’s attendance in clinic, they will incur huge medical costs. Therefore, the purpose of the present study is to present a quantitative method to...