Cyclic virtual test on wood furniture by Monte Carlo simulation: from compression behavior to connection modeling

Prediction of durability of wood product is a major challenge and an important goal for furniture industry. Numerical simulation based on approximation methods such as the finite element method (FEM) is an efficient and powerful tool to address this challenge while avoiding expensive experimental testing campaigns. Nevertheless, the strong heterogeneity of wood-based materials, the specific geometrical characteristics of wood-based structures (such as furniture that can often be represented as an assembly of beams, plates and/or shells) and the complex nonlinear 3D local behavior near the connections between structural parts may induce some difficulties in the numerical modeling and virtual testing of furniture for robust design purposes. Especially, when cyclic loading occurs, the behavior of junctions in furniture involves a local permanent strain that increases with the number of cycles and that can lead to an important gap potentially affecting the structural integrity of furniture. In this paper, we present an experimental campaign of cyclic compression tests carried out on spruce specimens. Theses specimens are cut out from a bunk bed and loaded under cyclic compression. The cyclic compression loading applied to the specimens leads to an evolution of the permanent strain during cycles that is modeled using a simple law describing the displacement gap as a function of the number of cycles. Considering the strong dispersion in the mechanical properties of wood-based materials and the variabilities induced by the experimental configuration, a stochastic modeling of the gap is proposed by having recourse to the maximum entropy (MaxEnt) principle in order to take into account the random uncertainties on the experimental setup and between the test specimens. The random mechanical response of a complex corner junction in a bunk bed under cyclic loading is then numerically simulated by using a Monte Carlo numerical simulation method as stochastic solver. This provides independent realizations of the random gap evolution (with respect to the number of cycles) in the bunk bed corner, allowing probabilistic quantities of interest related to the random gap, such as first- and second-order statistical moments (mean value, standard deviation) as well as confidence regions (with a given probability level), to be estimated.

Language bias and proficiency effects on cross-language activation

Recent research proposes that language bias and proficiency modulate cross-language activation in comprehension and production, but it is unclear how they operate and whether they interact. This study investigates whether stress differences between Spanish-English cognates (material, final-syllable stress in Spanish) affect how native-English second-language-Spanish bilinguals recognize Spanish words (materia “subject/matter,” second-syllable stress in Spanish). In a Spanish-English eye-tracking experiment (and parallel production task), participants heard/produced trisyllabic Spanish targets with second-syllable stress (materia) and saw four orthographic words, including the target and a Spanish-English cognate competitor. Cross-language activation was examined by manipulating the stress of the cognate in English. In comprehension, English cognates with the same stress as the Spanish target (materia vs material) were predicted to cause more cross-language interference than English cognates with a different stress (litera “bunk bed,” vs literal), but the reverse pattern was expected in production. Participants were assigned to a Spanish-bias condition (20% of English (filler) items), or an English-bias condition (65% of English (filler) items). Results indicate that English cognates with the same stress as the Spanish target interfered with the recognition of the Spanish target only in the English-bias condition (but facilitated its production), while increasing Spanish proficiency helped reduce this cross-linguistic interference.

Injuries associated with bunk beds occurring at schools: results using a US national data base

ObjectiveTo investigate bunk bed injuries occurring across all educational institutions using a national data base.MethodsNational Electronic Injury Surveillance System data for the years 2006–2015 associated with bunk beds was analysed.ResultsThere were an estimated 639 700 emergency department (ED) visits for bunk bed injuries; 1.3% occurred at school. Those occurring at school were older than those not at school (18.2 vs 12.8 years), and more commonly female (56.4% vs 40.6%), Caucasian (91.7% vs 68.3%) and associated with alcohol (10.8% vs 0.4%). For those occurring at school, the average age for those involving the trunk, upper extremity, lower extremity and head/neck areas was 17.9, 14.9, 19.2 and 18.7 years, respectively (p<10−4). A fracture was present in 6.4%, 52.3%, 21.2% and 9.6% of the trunk, upper extremity, lower extremity and head/neck areas, respectively (p=0.009). Males had a higher percentage of lacerations and females had a higher percentage of internal organ injuries. The vast majority of the fractures and strain/sprains occurred in the extremities; lacerations in the head/neck and contusion/abrasions predominantly involved the extremities and head/neck.Conclusions1.3% of all ED visits due to bunk bed injuries occurred in places of education. The majority of these were during college age. Prevention strategies should be directed at educational institutions and students, as well as following proper bunk bed equipment guidelines. Education regarding alcohol risks might assist college age students.

Emergency department surveillance of injuries associated with bunk beds: the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP), 1990–2009

Introduction Due to space constraints, bunk beds are a common sleeping arrangement in many homes. The height and design of the structure can present a fall and strangulation hazard, especially for young children. The primary purpose of this study was to describe bunk bed-related injuries reported to the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP), 1990–2009. Methods CHIRPP is an injury and poisoning surveillance system operating in 11 pediatric and 4 general emergency departments across Canada. Records were extracted using CHIRPP product codes and narratives. Results Over the 20-year surveillance period, 6002 individuals presented to Canadian emergency departments for an injury associated with a bunk bed. Overall, the frequency of bunk bed-related injuries in CHIRPP has remained relatively stable with an average annual percent change of 21.2% (21.8% to 20.5%). Over 90% of upper bunk-related injuries were due to falls and children 3–5 years of age were most frequently injured (471.2/100 000 CHIRPP cases). Conclusion Children with bunk bed-related injuries continue to present to Canadian emergency departments, many with significant injuries. Injury prevention efforts should focus on children under 6 years of age.

Fatality in the Side of a Bunk Bed

Mandatory and voluntary standards for bunk beds were written to eliminate the risk of head and neck entrapment in end panels. However, these standards do not address entrapment potential in the area of a side-mounted ladder. This article profiles the fatal strangulation of one child whose head and neck slipped into the space between the side ladder and lower bunk. The use of anthropometry data was essential in detecting this design hazard. Moreover, had this type of analysis been conducted prior to the product’s entry into the marketplace, this hazard could have been prevented.