Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies

Injury claims associated with minimal damage rear impact traffic crashes are often defended using a “biomechanical approach,” in which the occupant forces of the crash are compared to the forces of activities of daily living (ADLs), resulting in the conclusion that the risk of injury from the crash is the same as for ADLs. The purpose of the present investigation is to evaluate the scientific validity of the central operating premise of the biomechanical approach to injury causation; that occupant acceleration is a scientifically valid proxy for injury risk. Data were abstracted, pooled, and compared from three categories of published literature: (1) volunteer rear impact crash testing studies, (2) ADL studies, and (3) observational studies of real-world rear impacts. We compared the occupant accelerations of minimal or no damage (i.e., 3 to 11 kph speed change or “delta V”) rear impact crash tests to the accelerations described in 6 of the most commonly reported ADLs in the reviewed studies. As a final step, the injury risk observed in real world crashes was compared to the results of the pooled crash test and ADL analyses, controlling for delta V. The results of the analyses indicated that average peak linear and angular acceleration forces observed at the head during rear impact crash tests were typically at least several times greater than average forces observed during ADLs. In contrast, the injury risk of real-world minimal damage rear impact crashes was estimated to be at least 2000 times greater than for any ADL. The results of our analysis indicate that the principle underlying the biomechanical injury causation approach, that occupant acceleration is a proxy for injury risk, is scientifically invalid. The biomechanical approach to injury causation in minimal damage crashes invariably results in the vast underestimation of the actual risk of such crashes, and should be discontinued as it is a scientifically invalid practice.

Wind and Gravity in Shaping Picea Trunks

Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling bending of trunks and wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a one-hour simulation with a large-eddy simulation model. The weakest points along the trunks of the three largest trees resisted mean above-canopy wind speeds ranging from 10.2 m s-1 to 12.7 m s-1 (3.3-fold in the strongest gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. The wind that breaks the trunks in their weakest points is close to breaking them in other points, supporting importance of bending moments caused by wind and gravity in evolution of trunk taper. This approach could also be used to model tree biomasses and how those may change with changing climate.

Rehabilitation in locomotor system lesions using innovative orthopedic devices

The studies performed were aimed at developing a comprehensive biomechanical approach and on its basis — special innovative orthopaedic devices and methods for the rehabilitation of persons with disabilities and patients with musculoskeletal disorders using these devices, as well as their testing. We considered the issues of hydrorehabilitation of children with consequences of cerebral palsy and provision of a lower extremity with hip joint lesions to be moved forward in sagittal plane during walking. Analysis and synthesis were carried out. We applied a comprehensive criteria system approach to consider the biomechanical systems «patient-orthopedic apparatus» and to develop biomechanical schemes. We designed and manufactured orthopaedic devices for ankle and wrist joints for hydrorehabilitation and an orthopaedic apparatus for the whole lower extremity with an electric drive corset, control system, and external energy source. Methods of using the developed orthopedic devices were proposed. The tests showed their high functionality and increased efficiency of hydrorehabilitation in special orthopedic apparatuses and provision of walking in apparatuses using the whole leg with a microprocessor and an external energy source.

ERGONOMIC EVALUATION OF STUDY DESKS AND CHAIRS USING ANTHROPOMETRY AND BIOMECHANICAL APPROACH AT AN-NURIYAH ISLAMIC BOARDING SCHOOL BONTOCINI JENEPONTO REGENCY

School is one of the places to study. Therefore, it requires facilities to support the sustainability of the process of teaching and learning to teach such as study desks and study chairs. However, when the activity of writing is performed using study desks and chairs, students tend to lean to the front, slouch and dangle their feet. Evaluation of the products ergonomically has to be adjusted with the usage in order that they are not going to cause various negative impacts for students that will take place in both the short term and the long one. As a consequence, this study is important to carry out to minimize the mismatch of study desks and chairs with students and to obtain the redesigned results of study desks and study chairs ergonomically. The anthropometric approach was used for the dimensions of the human body in the design of study desks and chairs. In addition, the biomechanical approach was utilized to evaluate good sitting position for students. The evaluation was observed from the calculation of compression pressure, which is the load that occurs in the neck and lumbar. The results of the design of the proposed study desks and chairs are more ergonomic and can accommodate anthropometric users; hence, parts of the study desks and chair can minimize the complaints perceived by students. Through the biomechanical approach, the results obtained the angle surface of the table of 200, the slope of the seat rest of 100º and the seat slope of 50º

Wind and Gravity in Shaping Picea Trunks

Background:Understanding why trunks (tree stems) are the size that they are is important. However, this understanding is fragmented into isolated schools of thought and has been far from complete. Realistic calculations on minimum trunk diameters needed to resist bending moments caused by wind and gravity would be a significant step forward. However, advancements using this biomechanical approach have been delayed by difficulties in modelling wind gusts. We felled and measured five Norway spruces (Picea abies) in an unthinned monoculture in southeastern Finland planted 67 years earlier. We focused on forces working on storm-bent (maximally bent) trees caused by gravity and the strongest gust in a one-hour simulation with a large-eddy simulation model. Results:The three largest trees resisted mean above-canopy wind speeds ranging from 10.2 m s-1 to 12.7 m s-1 (3.3-fold in the gust), but the two smallest were well protected by a dense layer of leaves from the bending tops of larger trees, and could have resisted stronger winds. Gravity caused approximately one quarter of the critical bending moments. Conclusions:Our biomechanical modelling of trunk taper based on wind and gravity leads to diameters close to those measured, and we discuss the potential causes of the deviations. This approach could also be used to model tree biomasses and how those may change with changing climate.