Inconsistency of threat level in soft armour standards, correlation of experimental tests to bullet X-ray 3D images

Fundamental to any ballistic armour standard is the reference projectile that is to be defeated. Typically, for certification, consistency of bullet geometry is assumed. Therefore, practical variations in bullet jacket dimensions can have far reaching consequences. Traditionally, internal dimensions have been analysed by physically sectioning bullets – an approach which rules out any subsequent ballistic assessment. The use of a non-destructive X-ray Computed Tomography (CT) method was demonstrated in [1]. Now, the authors apply this technique to correlate bullet impact response to jacket thickness variations. A set of 20 bullets (9 mm DM 11) was selected to analyse both intra and inter bullet variations using an image based analysis method to map the jacket thickness and measure the centre of gravity. Thickness variations of the order of 200μm were found commonly across all the bullets along the length and an angular variation of up to 50μm was found in a few bullets. The bullets were subsequently impacted against a rigid flat plate and re-scanned. The results of the experiments are shown and compared to the un-deformed bullet jacket thickness variations. The conclusions are relevant for future soft armour standards and provide important data for numerical model correlation and development

Rapid design of crash properties for safe automobiles : a conceptual approach

+163hlm.;24c

Inconsistency in 9mm bullets measured with non-destructive X-ray computed tomography

Fundamental to any ballistic armour standard is the reference projectile that is to be defeated. Typically, for certification, consistency of bullets is assumed. Therefore, practical variations in bullet jacket dimensions can have far reaching consequences. Traditionally, internal dimensions could only be analysed by cutting bullets which rules out any subsequent ballistic assessment. Therefore, the use of a non-destructive X-raycomputedtomography (CT) method is explored in this paper. A set of 10 bullets (9 mm DM11) was taken for analysing both intra and inter bullet jacket thickness variation. CT measurements of jacket thickness were validated with high resolution scanning electron microscope (SEM) images. An image based analysis methodology has been developed to extract the jacket thickness map and the centre of gravity. Thickness variations of the order of 200 μm were found commonly across all the bullets along the length and an angular variation of up to 100 μm was found in a few bullets. Jacket thickness and centre of gravity were also calculated for the same bullets after impact and the variations between the pre- and post-impacted bullets were compared, by establishing a common physical reference. The results show that the proposed CT scanning approach and subsequent image analysis method can bring out the statistical variations in bullet geometry pre- and post impact effectively

Factors associated with return to work after open reinsertion of the triangular fibrocartilage

The aim of this study was to assess return to work (RTW) after open Triangular Fibrocartilage Complex (TFCC) reinsertion. RTW after open surgery for TFCC injury was assessed by questionnaires at 6 weeks, 3 months, 6 months, and 12 months post-operatively. Median RTW time was assessed on inverted Kaplan–Meier curves and hazard ratios were calculated with Cox regression models. 310 patients with a mean age of 38 years were included. By 1 year, 91% of the patients had returned to work, at a median 12 weeks (25%–75%: 6–20 weeks). Light physical labor (HR 3.74) was associated with RTW within the first 15 weeks; this association altered from 23 weeks onward: light (HR 0.59) or moderate physical labor (HR 0.25) was associated with lower RTW rates. Patients with poorer preoperative Patient-Rated Wrist Evaluation (PRWE) total score returned to work later (HR 0.91 per 10 points). Overall cost of loss of productivity per patient was €13,588. In the first year after open TFCC reinsertion, 91% of the patients returned to work, including 50% within 12 weeks. Factors associated with RTW were age, gender, work intensity, and PRWE score at baseline

Prognostic Factors in Open Triangular Fibrocartilage Complex (TFCC) Repair

Purpose: Patients with triangular fibrocartilage complex (TFCC) injury report ulnar-sided wrist pain and impaired function. Open TFCC repair aims to improve the condition of these patients. Patients have shown reduction in pain and improvement in function at 12 months after surgery; however, results are highly variable. The purpose of this study was to relate patient (eg, age and sex), disease (eg, trauma history and arthroscopic findings), and surgery factors (type of bone anchor) associated with pain and functional outcomes at 12 months after surgery. Methods: This study included patients who underwent an open TFCC repair between December 2011 and December 2018 in various Xpert Clinics in the Netherlands. All patients were asked to complete Patient-Rated Wrist Evaluation (PRWE) questionnaires at baseline as well as at 12 months after surgery. Patient, disease, and surgery factors were extracted from digital patient records. All factors were analyzed by performing a multivariable hierarchical linear regression. Results: We included 274 patients who had received open TFCC repair and completed PRWE questionnaires. Every extra month of symptoms before surgery was correlated with an increase of 0.14 points on the PRWE total score at 12 months after surgery. In addition, an increase of 0.28 points in the PRWE total score at 12 months was seen per extra point of PRWE total score at baseline. Conclusions: Increased preoperative pain, less preoperative function, and a longer duration of complaints are factors that were associated with more pain and less function at 12 months after open surgery for TFCC. This study arms surgeons with data to predict outcomes for patients undergoing open TFCC repair. Type of study/level of evidence: Prognostic II.</p