scholarly journals Forensic Engineering Analysis Of safety Shooting Glasses subject To Ballistic Impact

2011 ◽  
Vol 28 (2) ◽  
Author(s):  
David Danaher
Keyword(s):  
Impact Resistance ◽  
National Standards ◽  
Engineering Analysis ◽  
Minimum Level ◽  
Absorbed Energy ◽  
Voluntary Standards ◽  
Minimum Requirements ◽  
Forensic Engineering ◽  
The Impact ◽  
Current Standards

Currently There Are Voluntary Standards In Place That Outline The Impact Resistance Of Safety Glasses.  although The Standards Set Forth By The American National Standards Institute (Ansi) Outline Testing that Can Be Used To Calculate A Minimum Level Of Energy Which The Lens Should Absorb, Independent Testing has Shown That The Performance Of Modern Safety Glasses Exceed The Minimum Requirements Of The absorbed Energy. This Paper Will Show The Level Of Energy Which A Random Sample Of Safety Glasses Can withstand And Compare The Results To The Current Standards.

scholarly journals Forensic Engineering Analysis of Dynamic Forces Created by Pedestrians Impacting Plate Glass at Different Speeds

2015 ◽  
Vol 32 (1) ◽  
Author(s):  
Michael Kravitz
Keyword(s):  
Impact Load ◽  
Building Code ◽  
Engineering Analysis ◽  
Glass Panel ◽  
Impact Speed ◽  
Dynamic Forces ◽  
Exit Door ◽  
Forensic Engineering ◽  
Pedestrian Impact ◽  
The Impact

This paper examines the effect of a pedestrian inadvertently impacting a glass panel adjacent to a glass exit door. The glass panel was full length and unmarked, violating the local building code and building commissioner directives. The defense argued that the old building code, to which the college building was constructed, was “grandfathered” and there was no violation. Initial witness and plaintiff statements indicated that the plaintiff was running when he struck the panel, which shattered and caused the plaintiff to incur injuries. The plaintiff testified later, in deposition, that he was walking when he struck the glass. The court needed to establish liability percentage, which is common in civil cases, and it was necessary to determine at what pedestrian impact speed the glass panel would break. The analysis used Timoshenko’s theory of vibration plates, Roark’s stress strain formulas, ergonomics, and human factors to estimate the impact load and stresses on the glass panel that caused failure.

Damage evaluation and protection method of resin pipe for gas conduit subjected to impact load

2020 ◽  
Vol 11 (4) ◽  
pp. 423-447 ◽  
Author(s):  
Hiroki Tamai ◽  
Sota Jinkawa ◽  
Yoshimi Sonoda
Keyword(s):  
High Density Polyethylene ◽  
Impact Test ◽  
Impact Resistance ◽  
High Density ◽  
Third Party ◽  
Medium Density ◽  
Absorbed Energy ◽  
Polyethylene Pipe ◽  
The Third ◽  
The Impact

Medium-density polyethylene pipe has been widely introduced to low-pressure gas pipes because of its high flexibility and corrosion resistance. However, many third-party damages due to the impact of heavy equipment have been reported during the construction every year, thus, to prevent the third-party damage, materials such as high-density polyethylene and polyamide have been considered as the new gas pipe candidates. However, their impact resistance capacity under the third-party attack has not been clarified. In this study, static and impact loading experiments were conducted to compare load resistance capacities. As a result, it was revealed that the high-density polyethylene pipe and the polyamide pipe had higher static load capacity and impact resistance than the medium-density polyethylene pipe. By comparing the absorbed energy of the static test and the impact test and calculating the pseudo absorbed energy of the impact test, the evaluation formula judging the safer side of whether the penetration occurred was proposed. Furthermore, as one of the methods to protect the gas pipe, the protective effect of winding a sheet made of reinforced fiber and non-woven fabric was clarified.

scholarly journals Forensic Engineering Analysis Of A Failed Energy Reduction Method For A Central Steam Distribution System

2012 ◽  
Vol 29 (1) ◽  
Author(s):  
Klas C. Haglid
Keyword(s):  
Distribution System ◽  
Reduction Method ◽  
National Standards ◽  
Energy Reduction ◽  
Engineering Analysis ◽  
National Reference ◽  
Short Period ◽  
Forensic Engineering ◽  
The Subject ◽  
Steam Pipe

A Forensic Engineer Was Asked To Visit The Subject University And While Walking Through The Site Noticed Areas Of The Underground Direct Buried Steam Pipe And The Manholes And Found Many Areas Of Rising Steam, Especially In The Area Of The Manholes. Several Of The Manholes Were Producing Visible Columns Of Steam. Ironically, This Central Steam Distribution System Was Engineered To Save Money, Time, Energy, And Improve The Functionality Of The Existing System. Documents Relevant To This Case Have Been Evaluated And National Standards In The Form Of Ashrae And Astm Have Been Referenced And Reviewed. Pictures, National Reference Standards, Material Data Sheets And Other Peer Reviewed Studies Will Be Used To Explain In Detail How A Large Central Steam Distribution System Started To Fail Dramatically And Catastrophically In A Very Short Period Of Time During And After Installation.

Influence of Structure Unit and the Distribution on the Low-Velocity Impact Property of the 3D Woven Composites

2012 ◽  
Vol 502 ◽  
pp. 169-173
Author(s):  
Yan Qing Li ◽  
Jia Ying Sun ◽  
Wei Tian ◽  
Cheng Yan Zhu
Keyword(s):  
Impact Resistance ◽  
Impact Property ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Material Structure ◽  
Absorbed Energy ◽  
Low Velocity ◽  
Velocity Impact ◽  
3D Woven Composites ◽  
The Impact

In this paper, the low-velocity impact properties of the 3D woven composites were tested. Through the study on the relationship of absorbed energy and material structure, the impact resistance of the composites has been discussed. The research results show that the low-velocity impact resistance of quasi-orthogonal composites is the best, the low-velocity impact resistance of orthogonal composites is the worst and angle tangled of interlayer joint composites stand somewhere between the two. Adding quasi-orthogonal unit into the structure, the low-velocity impact property of the composites can be enhanced efficiently. On the other hand, if the unit distribution of the enforced fabric is changed, the break time and break point will be changed. But the effect on the total absorbed energy is not obvious.

scholarly journals Comparative Study on the Impact Wedge-Peel Performance of Epoxy-Based Structural Adhesives Modified with Different Toughening Agents

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1549
Author(s):  
Gyeong-Seok Chae ◽  
Hee-Woong Park ◽  
Jung-Hyun Lee ◽  
Seunghan Shin
Keyword(s):  
Shear Strength ◽  
Automotive Industry ◽  
Impact Resistance ◽  
High Energy ◽  
Epoxy Adhesive ◽  
Absorbed Energy ◽  
Structural Adhesives ◽  
Epoxy Adhesives ◽  
The Impact ◽  
Modified Epoxy

Epoxy adhesives are widely used in various industries because of their high heat and chemical resistance, high cohesion, and minimal shrinkage. Recently, epoxy adhesives have been applied in the automotive industry as structural adhesives for lightweight vehicles. However, the brittleness of the epoxy is an obstacle for this application, since the automotive industry requires epoxy-based structural adhesives to have a high level of high-speed impact resistance. Hence, we used phenol-terminated polyurethane (PTPU) as a toughening agent for epoxy adhesives and compared the results with those that were obtained with carboxyl-terminated butadiene acrylonitrile copolymer (CTBN). The high-energy impact resistance of the epoxy adhesives was measured by the impact wedge-peel (IWP) test, and the shear strength was measured by the single lap joint test. As a result, the 20 wt % PTPU-modified epoxy adhesive showed remarkably higher total absorbed energy (25.8 J) during the IWP test and shear strength (32.3 MPa) as compared with the control epoxy adhesive (4.1 J and 20.6 MPa, respectively). In particular, the total absorbed energy of the PTPU-modified epoxy adhesive was much larger than that of the CTBN-modified epoxy adhesive (5.8 J). When more than 10 wt % PTPU was added, the modified epoxy adhesives showed stable crack growth and effectively transferred external stress to the substrate. These results were explained by changes in the glass transition temperature, crosslinking density, and morphology due to the toughening agents.

scholarly journals Forensic Engineering Analysis of a Failed ROPS

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
Daniel Cowley
Keyword(s):  
Energy Absorption ◽  
Laboratory Testing ◽  
Center Of Gravity ◽  
Engineering Analysis ◽  
Liquid Manure ◽  
The Past ◽  
Forensic Engineering ◽  
Protective Structures ◽  
Current Standards

Agricultural, commercial, and some lawn and garden tractors have been known to tip and roll over. Roll-over protective structures (ROPS) are designed to assure seat-belted occupants can survive in a zone of clearance within the structure, during and following a roll-over event. Within the laboratory testing parameters established in the current standards, energy absorption is based on tractor mass alone, apart from any other forces that may be acting on the tractor. Current standards allow tractor manufacturers to determine the “reference mass” used for ROPS testing. Most manufacturers fail to include the mass of any attached implements. When implements remain attached to the tractor throughout the roll-over event, ROPS should still be designed to protect operators. In the past, tractors were mainly employed in soil-engaging or surface-grooming exercises. The center of gravity (CG) of these attached implements was relatively low. Today, however, tractors may tow larger, taller, and heavier implements with high CG on multiple axles, such as large liquid manure tank spreaders. The purpose of this paper is to investigate the physical issues associated with tractors towing high CG implements, such as geometrically tall, articulated steerable axle spreaders operating in sloped terrain that cause an ROPS to fail.

scholarly journals Forensic Engineering Analysis Of A Contractor/Subcontractor Dispute

2013 ◽  
Vol 30 (2) ◽  
Author(s):  
George R. Barbour
Keyword(s):  
Built Environment ◽  
Building Codes ◽  
National Standards ◽  
Market Forces ◽  
Engineering Analysis ◽  
Regulatory Requirements ◽  
Technical Aspects ◽  
The Past ◽  
General Contractors ◽  
Forensic Engineering

Construction Defects And The Resulting Disputes Between Contractors And Their Various Subcontrac-Tors Are Not A Recent Concept. However, With The Proliferation Of Specialized Licensing Requirements, Building Codes, Regulations, And National Standards, Threshold Requirements For The Built Environment Are Now Significantly Better Defined Than In The Past. Market Forces Have Led Most General Contractors To Contract Out Most Of The Actual Work In Lieu Of Self-Performing. As A Result, Construction Dispute Claims Have Become More Common And Complex. The Forensic Engineer Must Consider Not Only The Technical Aspects Of A Claim But The Contractual And Regulatory Requirements As Well, When Tasked With Distributing Culpability Between The Various Parties. The Purpose Of This Article Is To Examine The Component Of The Dispute Between The Contractor And Subcontractor With Specific Focus On The Regulatory And Contractual Requirements.

scholarly journals Forensic Engineering Analysis Of A Campus Wide Steam Loop Failure

2013 ◽  
Vol 30 (2) ◽  
Author(s):  
Klas C. Haglid
Keyword(s):  
Distribution System ◽  
National Standards ◽  
Engineering Analysis ◽  
National Reference ◽  
Short Period ◽  
Forensic Engineering ◽  
The Subject ◽  
A Site ◽  
Time And Energy ◽  
Steam Pipes

A Forensic Engineer Invited To Investigate A Heating Problem At A University Recently Made A Site Visit At The Subject University. While Walking Through The Site He Noticed Many Areas Of Rising Steam, Especially In The Area Of The Manholes Provided For Underground Direct Burial Steam Pipes. Several Of The Manholes Were Producing Visible Columns Of Steam. Ironically, This Central Steam Distribution System Was Engineered To Save Money, Time, And Energy And Improve The Functionality Of The Existing System. Documents Relevant To This Case Were Evaluated And National Standards In The Form Of Ashrae And Astm Were Referenced And Reviewed. Pictures, National Reference Standards, Material Data Sheets And Other Peer-Reviewed Studies Will Be Used To Explain In Detail How A Large Central Steam Distribution System Started To Fail Dramatically And Catastrophically In A Very Short Period During And After Installation.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

scholarly journals Effect of SWCNT-Tuball Paper on the Lightning Strike Protection of CFRPs and Their Selected Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3140
Author(s):  
Kamil Dydek ◽  
Anna Boczkowska ◽  
Rafał Kozera ◽  
Paweł Durałek ◽  
Łukasz Sarniak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Copper Foil ◽  
Impact Resistance ◽  
Mechanical Analysis ◽  
Lightning Strike ◽  
Single Wall Carbon Nanotubes ◽  
Carbon Fibre Reinforced Polymer ◽  
The Impact

The main aim of this work was the investigation of the possibility of replacing the heavy metallic meshes applied onto the composite structure in airplanes for lightning strike protection with a thin film of Tuball single-wall carbon nanotubes in the form of ultra-light, conductive paper. The Tuball paper studied contained 75 wt% or 90 wt% of carbon nanotubes and was applied on the top of carbon fibre reinforced polymer before fabrication of flat panels. First, the electrical conductivity, impact resistance and thermo-mechanical properties of modified laminates were measured and compared with the reference values. Then, flat panels with selected Tuball paper, expanded copper foil and reference panels were fabricated for lightning strike tests. The effectiveness of lightning strike protection was evaluated by using the ultrasonic phased-array technique. It was found that the introduction of Tuball paper on the laminates surface improved both the surface and the volume electrical conductivity by 8800% and 300%, respectively. The impact resistance was tested in two directions, perpendicular and parallel to the carbon fibres, and the values increased by 9.8% and 44%, respectively. The dynamic thermo-mechanical analysis showed higher stiffness and a slight increase in glass transition temperature of the modified laminates. Ultrasonic investigation after lightning strike tests showed that the effectiveness of Tuball paper is comparable to expanded copper foil.

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