The Development of a Substitute Bird Model

1981 ◽  
Vol 103 (4) ◽  
pp. 725-730 ◽  
Author(s):  
James S. Wilbeck ◽  
James L. Rand
Keyword(s):  
Impact Loading ◽  
Impact Testing ◽  
Hydrodynamic Theory ◽  
Impact Event ◽  
Loading History ◽  
Comprehensive Program ◽  
Engine Blade ◽  
History Of ◽  
The Impact

A comprehensive program was conducted to develop a model synthetic bird for use in engine blade impact testing. A hydrodynamic theory of the impact event was used to aid in determining the bird properties which had to be duplicated in the model. Of the two candidate models studied extensively, it was determined that a projectile fabricated from commercial gelatin impregnated with phenolic mircoballoons most nearly duplicated the impact loading history of real birds.

scholarly journals Investigation on the Application of Taylor Impact Test to High-G Loading

2021 ◽  
Vol 8 ◽  
Author(s):  
Li Juncheng ◽  
Chen Gang ◽  
Lu Yonggang ◽  
Huang Fenglei
Keyword(s):  
Pulse Duration ◽  
Impact Loading ◽  
Impact Test ◽  
Impact Load ◽  
Low Cost ◽  
Large Mass ◽  
Impact Testing ◽  
Taylor Impact ◽  
Taylor Impact Test ◽  
The Impact

Taylor impact test is characterized by high impact energy, low cost, and good repeatability, giving it the technical foundation and development potential for application in high-g loading. In this paper, the feasibility of performing high-g load impact testing to a missile-borne recorder by conducting Taylor impact test was studied by combining simulation analyses with experimental verification. Acccording to the actual dimensions of the missile-borne recorder, an experimental piece was designed based on the Taylor impact principle. The impact loading characteristics of the missile-borne recorder were then simulated and analyzed at different impact velocities. In addition, the peak acceleration function and the pulse duration function of the load were fitted to guide the experimental design. A Taylor-Hopkinson impact experiment was also conducted to measure the impact load that was actually experienced by the missile-borne recorder and the results were compared with the results of strain measurements on the Hopkinson incident bar. The results showed that the peak value of impact load, the pulse duration and the waveform of the actual experimental results were in good agreement with the results predicted by the simulations. Additionally, the strain data measured on the incident bar could be used to verify or replace the acceleration testing of the specimen to simplify the experimental process required. Based on the impact velocity, high-g loading impact was achieved with peak values in the 7,000–30,000 g range and durations of 1.3–1 ms, and the waveform generated was a sawtooth wave. The research results provide a new approach for high amplitude and long pulse duration impact loading to large-mass components, and broaden the application field of Taylor impact test.

scholarly journals Analisa Kekuatan Impak Helmet Sepeda Motor Metode Impak Jatuh Bebas

2017 ◽  
Vol 2 (1) ◽  
pp. 42
Author(s):  
Rahmat Kartolo Simanjuntak
Keyword(s):  
Impact Loading ◽  
Minimum Energy ◽  
Free Fall ◽  
Load Cell ◽  
Impact Testing ◽  
Time Signal ◽  
Research Activity ◽  
Testing Apparatus ◽  
Impact Time ◽  
The Impact

The non-standard helmet testing is required for measure the helmet strength as effect of the load is given. In generally, traffic accident doesn�t involved by the velocity but also gravitational. Therefore, the research activity is done by researcher obtains the effect of free-fall impact loading on the non-standard helmet. The information which is obtained from this research will explain the effect of free-fall impact loading that is subjected on the non-standard helmet to user, industry, and also government. The objective of this research involves the testing apparatus construction of free-fall impact loading on the non-standard helmet, measuring the maximum impact loading, and the energy absorbing by helmet as effect of impact loading. The researcher collaborates with the Impact and Fracture Reaseach Center (IRFC) has bulit the testing apparatus which is equipped with good aquisition data system. The non-standar helmet is put on the adjustable testing rig. The impact time can be measured by eight inductive proximity sensors. The helmet will slide down and collides the anvil. The force will be measured with the load cell which is put down the anvil. There are four anvil forms which is adapted to the real condition, that is: flat plat, aligned plat, bullet, and a half-spherical anvil. The data will be transfered from the load cell into the DAQ system which has function to change the analog into digital signal. Finally, the data will be saved into PC as the force (N) and the impact time (ms). The free-fall impact testing equipment has shown the best performance on the force and impact time signal reading as long as the research activity. The maximum force on the flat anvil is 24.33 N; the aligned flat anvil is 37.88 N; the bullet anvil is 16.22 N; and a half-spherical anvil is 41.43 N at the elevation of 0.75 m. The minimum energy which causes the fracture on the helmet is 3.24 J at the elevation of 0.3 m.

Energy-Absorbing Capacity of Polyurethane/SiC/Glass-Epoxy Laminates Under Impact Loading

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
G. Balaganesan ◽  
V. Akshaj Kumar ◽  
V. C. Khan ◽  
S. M. Srinivasan
Keyword(s):  
Energy Absorption ◽  
Impact Loading ◽  
Composite Laminate ◽  
Failure Modes ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Fiber Failure ◽  
The Impact ◽  
Layered Target

This paper presents the energy absorption of target materials with combinations of polyurethane (PU) foam, PU sheet, SiC inserts, and SiC plate bonded to glass fiber reinforced composite laminate backing during impact loading. SiC inserts and SiC plates are bonded as front layer to enhance energy absorption and to protect composite laminate. The composite laminates are prepared by hand lay-up process and other layers are bonded by using epoxy. Low-velocity impact is conducted by using drop mass setup, and mild steel spherical nosed impactor is used for impact testing of target in fixed boundary conditions. Energy absorption and damage are compared to the target plates when subjected to impact at different energy levels. The energy absorbed in various failure modes is analyzed for various layers of target. Failure in the case of SiC inserts is local, and the insert under the impact point is damaged. However, in the other cases, the SiC plate is damaged along with fiber failure and delamination on the composite backing laminate. It is observed that the energy absorbed by SiC plate layered target is higher than SiC inserts layered target.

scholarly journals A-110 Are Invalid Baselines More Frequent in those with Concussion History?

2020 ◽  
Vol 35 (6) ◽  
pp. 903-903
Author(s):  
Maietta J ◽  
Hopkins N ◽  
Maietta L ◽  
Flood S ◽  
Johnson L ◽  
...  
Keyword(s):  
High School ◽  
Test Performance ◽  
Impact Testing ◽  
Cognitive Testing ◽  
Return To Play ◽  
Future Research ◽  
High School Athletes ◽  
History Of ◽  
Concussion History ◽  
The Impact

Abstract Objective The Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) is a commonly utilized measure for sports concussion. Across the literature we have reviewed there is an abundance of information that focuses on invalid baselines and the effects of concussions. Yet, no previous studies have investigated the effect of a history of concussion on frequency of invalid baselines. The current study examined these effects within high school athletes. Methods Participants included 47,874 high school athletes (mean age = 15.0, SD = 1.2; mean education = 9.0; SD = 1.5; 42.6% female). These athletes were selected from a larger database of athletes who completed baseline ImPACT testing from 2008–2016. Self-reported history of concussion (none vs. 1+) was obtained from the demographic section of the ImPACT. Invalid performance was based on standard ImPACT criteria (“Baseline++”). Results Chi-square tests of homogeneity were performed to assess differences in invalid baselines between those with and without a history of concussion. Results revealed significantly more invalid baselines for those with a history of concussion (p < .01). Conclusions Results indicate that high school athletes with a self-reported history of concussion may be more likely to have invalid baseline test performance. Based on these preliminary results, clinicians who are managing return-to-play decisions may want to take into account concussion history when interpreting baseline data. Future research should, of course, investigate whether this result is consistent in other samples and, if so, whether alternative validity criteria may be needed. Future investigations of athletes with confirmed clinical diagnosis of concussion is an important next step in investigating differences in rates of invalid baselines.

scholarly journals Fiber Bragg Gratings Array for Structural Health Monitoring

2008 ◽  
Vol 47-50 ◽  
pp. 407-410 ◽  
Author(s):  
B.L. Chen ◽  
C.S. Shin
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Source Location ◽  
Impact Testing ◽  
Impact Event ◽  
Event Monitoring ◽  
Impact Location ◽  
Rolled Aluminum ◽  
Propagation Pattern ◽  
The Impact

Impact event monitoring and source location in some critical structures. The current work evaluated the feasibility and limitation of using fiber Bragg gratings (FBGs) for this purpose. Impact testing carried out on a cold rolled aluminum plate showed that impact event monitoring with the FBGs is feasible with the current intensity modulation interrogation method. Source location is successful at part of the impact location but not at the others. This phenomenon is caused by the complex wave propagation pattern on the plate so that differently oriented FBGs receive the signal from the same impact at different time.

Prediction of Energy Absorption Capability of Curved Panel Structure; For Wing Leading Edge Study

2012 ◽  
Vol 225 ◽  
pp. 178-182
Author(s):  
Nurihan Omar ◽  
Nur Aisyah Md Khalid ◽  
Nor Fadilah Shamsudin ◽  
Yulfian Aminanda
Keyword(s):  
Energy Absorption ◽  
Impact Loading ◽  
Leading Edge ◽  
Impact Testing ◽  
Experimental Results ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Edge Structure ◽  
Curved Panel ◽  
The Impact

This paper works on the curvature effect of wing leading edge structure subjected to impact loading. At first stage, rigid spherical projectile and semi-elliptical panel were used. The impact testing has been carried out by varying the radius of curvature and the thickness of the panel. The experimental results show the trend of specific energy absorption capability of structure in function of the radius and thickness of panel. From experimental observation, it shows that the failure of structure subjected to impact loading can be distinguished in two types of failure; the projectile went through the structure and large displacement of curved panel. The two failure criteria are used later on to determine the energy absorption capability using Finite Element Analysis method. A FEA model is proposed to simulate the behavior of curved composite structure and validated by the experimental results in order, as final goal, to propose the simulation as a tool of designing the leading edge of wing with an optimum radius curvature and thickness of wing leading edge panel to absorb a specific magnitude of impact energy.

scholarly journals Impact Testing of 3D Re-Entrant Honeycomb Polyamide Structure Using Split Hopkinson Pressure Bar

2021 ◽  
Vol 11 (21) ◽  
pp. 9882
Author(s):  
Jiangping Chen ◽  
Weijun Tao ◽  
Shumeng Pang
Keyword(s):  
Energy Absorption ◽  
Impact Velocity ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Impact Testing ◽  
Hopkinson Pressure Bar ◽  
Static Test ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

In this study, a total of 30 3D re-entrant honeycomb specimens made of polyamide were fabricated with various configurations by using the additive manufacturing (AM) technique. Split Hopkinson Pressure Bar (SHPB) tests were conducted on the RH specimens at different impact velocities. The incident, reflected and transmitted waveforms can well explain the wave propagation and energy absorption characteristics of the specimens, which can help us to understand and analyse the process of impact loading. The stress–strain curves, energy absorption ability and failure modes of SHPB tests with different impact velocities and quasi-static compression tests were analysed and compared, and it was found that the flow stress and energy absorption ability of the specimens subjected to impact load were much improved. Among the tested specimens, specimen C2, with a smaller re-entrant angle θ, displayed the best energy absorption ability, which was 1.701 J/cm3 at the impact velocity of 22 m/s and was 5.1 times that in the quasi-static test. Specimen C5 had the longest horizontal length of the diagonal bar L0, and its energy absorption was 1.222 J/cm3 at the impact velocity of 22 m/s and was 15.7 times that in the quasi-static test, reflecting the superiority of a structurally stable specimen in energy absorption under impact loading. The test results can provide a reference for the optimization of the design of the same or similar structures.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

The Film World’s Cooperative Store: Institutions and Films of the 1930s and 1940s

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
World War Ii ◽  
Meat Products ◽  
Public Information ◽  
Early History ◽  
World War ◽  
International Context ◽  
German Occupation ◽  
History Of ◽  
The Uk ◽  
The Impact

This chapter traces the early history of state-sponsored informational filmmaking in Denmark, emphasising its organisation as a ‘cooperative’ of organisations and government agencies. After an account of the establishment and early development of the agency Dansk Kulturfilm in the 1930s, the chapter considers two of its earliest productions, both process films documenting the manufacture of bricks and meat products. The broader context of documentary in Denmark is fleshed out with an account of the production and reception of Poul Henningsen’s seminal film Danmark (1935), and the international context is accounted for with an overview of the development of state-supported filmmaking in the UK, Italy and Germany. Developments in the funding and output of Dansk Kulturfilm up to World War II are outlined, followed by an account of the impact of the German Occupation of Denmark on domestic informational film. The establishment of the Danish Government Film Committee or Ministeriernes Filmudvalg kick-started aprofessionalisation of state-sponsored filmmaking, and two wartime public information films are briefly analysed as examples of its early output. The chapter concludes with an account of the relations between the Danish Resistance and an emerging generation of documentarists.

A Left History of Liquorice: What It Means to Write "Left" History

2019 ◽  
Vol 23 (1) ◽  
Author(s):  
Bryan D. Palmer
Keyword(s):  
Historical Study ◽  
Right Wing ◽  
Special Edition ◽  
Political Climate ◽  
Historical Approach ◽  
History Of ◽  
The Impact

This article is part of a special Left History series reflecting upon changing currents and boundaries in the practice of left history, and outlining the challenges historians of the left must face in the current tumultuous political climate. This series extends a conversation first convened in a 2006 special edition of Left History (11.1), which asked the question, “what is left history?” In the updated series, contributors were asked a slightly modified question, “what does it mean to write ‘left’ history?” The article charts the impact of major political developments on the field of left history in the last decade, contending that a rising neoliberal and right-wing climate has constructed an environment inhospitable to the discipline’s survival. To remain relevant, Palmer calls for historians of the left to develop a more “open-ended and inclusive” understanding of the left and to push the boundaries of inclusion for a meaningful historical study of the left. To illustrate, Palmer provides a brief materialist history of liquorice to demonstrate the mutability of left history as a historical approach, rather than a set of traditional political concerns.

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